THE DEVELOPMENT OF A GENERIC WATER SAFETY PLAN FOR SMALL COMMUNITY WATER SUPPLY
Peter Thompson & Sameera Majam
Report to the Water Research Commission
by
Umgeni Water
WRC Report No. TT 415/09
August 2009
ii
Obtainable from Water Research Commission Private Bag X03 Gezina 0031 The publication of this report emanates from a project entitled Compilation of a generic safety plan for small community water supply (WRC Project No: K8/649//3).
ISBN 978-1-77005-881-1 Printed in the Republic of South Africa
DISCLAIMER
The report has been reviewed by the Water Research Commission (WRC) and approved for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the WRC, nor does mention of trade names or commercial products constitute endorsement or recommendation for use.
iii
TABLE OF CONTENTS LIST OF FIGURES ........................................................................................................................ iv LIST OF TABLES .......................................................................................................................... iv LIST OF ABBREVIATIONS ........................................................................................................... iv SECTION 1: INTRODUCTION .................................................................................................... 1 1.1 BACKGROUND ..................................................................................................................... 1 1.2 CURRENT METHODS OF ASSESSING WATER QUALITY ................................................ 2 1.3 CONSTRAINTS OF USING INDICATORS TO PREDICT RISKS ......................................... 2 1.4 BENEFITS OF USING THE WATER SAFETY PLAN ........................................................... 3 SECTION 2: METHODOLOGY ON HOW TO DEVELOP A WATER SAFETY PLAN ................. 5 2.1 ASSEMBLE A TEAM TO CARRY OUT THE WATER SAFETY PLAN ................................. 5 2.2 DOCUMENT AND DESCRIBE THE SYSTEM ...................................................................... 6 2.3 ASSESS THE EXISTING PROPOSED SYSTEM (INCLUDING A DESCRIPTION OF
THE PROCESS AND A FLOW DIAGRAM) ........................................................................... 6 2.4 UNDERTAKE A HAZARD ASSESSMENT AND A RISK CHARACTERIZATION TO
IDENTIFY AND UNDERSTAND HOW HAZARDS CAN ENTER INTO THE WATER SUPPLY ................................................................................................................................ 8
2.5 IDENTIFY CONTROL MEASURES – THE MEANS BY WHICH RISKS CAN BE CONTROLLED .................................................................................................................... 10
2.6 DEFINE MONITORING OF CONTROL MEASURES – WHAT LIMITS DEFINE ACCEPTABLE PERFORMANCE AND HOW THESE ARE MONITORED .......................... 13
2.7 ESTABLISH PROCEDURES TO VERIFY THAT THE WATER SAFETY PLAN IS WORKING EFFECTIVELY AND WILL MEET THE HEALTH-BASED TARGETS ............... 15
2.8 DEVELOP SUPPORTING PROGRAMMES ........................................................................ 15 2.9 PREPARE MANAGEMENT PROCEDURES ...................................................................... 16 2.10 ESTABLISH DOCUMENTATION AND COMMUNICATION PROCEDURES ..................... 20 2.11 REVIEW OF THE WSP ....................................................................................................... 20 SECTION 3: CHECKLIST FOR CONDUCTING A WSP .............................................................. 21 SECTION 4: REFERENCES ........................................................................................................ 22 ANNEXURE A: RISK ASSESSMENT FORM ............................................................................... 24 ANNEXURE B: CORRECTIVE ACTIONS .................................................................................... 34
iv
LIST OF FIGURES Figure 1: Constituents that must be measured at different points in the supply system when
assessing water quality .................................................................................................. 3 Figure 2: Steps used to guide an assessment of water supply based on the WSP approach ........ 4 Figure 3: Institutional framework for the provision of potable water in South Africa ........................ 5 Figure 4: Symbol chart for drawing flow diagrams of water treatment systems .............................. 7 Figure 5: An example of a flow diagram for a system ..................................................................... 7 LIST OF TABLES Table 1: Factors for consideration during the documentation and description of the system ......... 6 Table 2: Sources of potential hazards or hazardous events in the water supply system ................ 9 Table 3: Risk Assessment Matrix ................................................................................................. 10 Table 4: Risk profile based on score calculated from risk assessment matrix .............................. 10 Table 5: Factors for Consideration ............................................................................................... 12 Table 6: Suggested sampling types and frequencies based on population served ...................... 14 Table 7: Incident Management Protocol for Health Related Drinking Water Quality Incidents ..... 17 Table 8: Incident Management Protocol for Aesthetic Drinking Water Quality Incidents .............. 19
LIST OF ABBREVIATIONS Cl2 - Chlorine gas CO2 - Carbon Dioxide DBPs - Disinfection By-products Fe - Iron GAC - Granular Activated Carbon HTH - Granular disinfectant chemical (sodium hypochlorite) MIB - Methyl-iso-borneol Mn - Manganese PAC - Powdered Activated Carbon UV - Ultraviolet WSPs - Water Safety Plans
1
SECTION 1: INTRODUCTION 1.1 BACKGROUND Since 1994, the South African government has directed its resources to ensure that the millions of under-serviced people in the country have access to a functioning basic water supply. To date, government has managed to provide clean, safe water to a total of 18.7 million people and in doing so has exceeded the Millennium Development Goals (Hendricks, 2008). Water service delivery demands have resulted in an exponential growth of small treatment plants in the country with many of these being situated in rural areas and with limited technical support. Management of these water supply systems has been very difficult and Water Service Authorities have to rely on limited resources to ensure that the water supply meets the minimum standards in terms of quantity and quality. As a developing country, South Africa faces many challenges in terms of providing water that meets the minimum standards for acceptable drinking water. These challenges are a result of: Unplanned development – Informal housing settlements in the resource area and in
urban/semi-urban areas make it difficult to control activities in the catchment area and to locate supply mains.
Poor sanitation – Poor access to urban sanitation, especially from the informal housing settlements, may result in the contamination of the water source and may also lead to the potential cross contamination of water pipes.
Locality (geographic factors) – Some plants are situated in rural areas and may not have sufficient finance and/or equipment resource availability to measure the appropriate water quality parameters.
Lack of system knowledge and technical skills – The operators and staff at water treatment plants do not have the proper qualifications and technical training required to run a plant.
Limited data availability – Many systems have only recently developed the culture of data collection and storage.
Socio-economic factors – A large percentage of the South Africa’s population are at/below the low income mark and are most likely to use contaminated water sources as they cannot afford to access better quality water sources. Some cannot afford, or do not know how, to conduct treatment within their homes, i.e. disinfection with a chlorine solution, e.g. Jik. This population group is at the greatest risk of infectious disease and illness from poor water supply.
Although water service delivery in South Africa has reached great milestones, the quality of water produced according to drinking water quality standards cannot always be ensured. This is evident by the amount of outbreaks that have occurred over time. The most recent incidents include: Bloemhof – 2006, Delmas – 2005 and Kanana – 2004. A recent survey of disinfection efficiency at 181 small drinking water treatment plants across South Africa revealed the following critical findings: Turbidity values at the point of consumption indicated that 46% of plants were compliant
within Class I and 41% were compliant within Class II of SANS 241:2006. Free chlorine concentrations at the point of consumption indicated that 32% of plants were
below 0.1 mg/L and 48% below 0.2 mg/L. The ideal target range according to SANS 241:2006 is between 0.2 and 0.5 mg/L.
At the point of consumption, 63% of plants were compliant for total coliforms and 66% were compliant for faecal coliforms.
The majority of operators lack relevant technical skills and appropriate training for plant operation. Their qualifications range from 24% with grade 10, 56% with grade 12 to 20% post grade 12.
2
Most plant supervisors and operators had no knowledge of flow rates at which plants operated.
Chemical dosing rates were determined by experience. The absence of a water quality monitoring programme in most plants was prominent. Some
plants use an external monitoring group at least once a month but do not receive regular feedback.
The maintenance of equipment in some plants was not taken into account. According to the survey (Momba, 2007), the shortfalls noted were due to various issues, i.e. poor maintenance practices, lack of training and capacity building, poor working conditions, insufficient financial capacity and poor recording, documentation and communication. 1.2 CURRENT METHODS OF ASSESSING WATER QUALITY Water quality assessments are conducted by the measurement of certain physical, chemical and microbiological constituents at different points in the water supply system, i.e. water source, treatment works, distribution system and point of use (WHO1). There are many constituents present in water but only those that occur in concentrations high enough to cause health and aesthetic problems are most important and are measured frequently. During a water quality assessment, tests are conducted for features referred to as general indicators that warn of potential problems in water quality. These are: conductivity, faecal coliforms, pH, turbidity and free chlorine (DWAF et al., 2001). Various other constituents can be measured to assess water quality. These constituents are listed in Figure 1 and are arranged in order of decreasing priority from Group A to Group D (DWAF et al., 2001). The frequency of monitoring is dependent on the size of population served. 1.3 CONSTRAINTS OF USING INDICATORS TO PREDICT RISKS Water quality assessments are more focused on the control of the means of measurement rather than ensuring that operational practices are consistent with producing water that meets the requirements of SANS 241. The elimination of pathogenic micro-organisms in the water supply is given higher priority in water quality control even though several other factors that lead to poor water quality are existent. The original development of water quality control has placed major emphasis on the control of bacterial diarrhoeal diseases such as cholera, typhoid and shigellosis (Chapman and Hall, 1992). Bacteria are agents that cause severe acute disease and are important to consider as they account for a sizeable proportion of cases of diarrhoeal disease in both developed and developing countries. Within developing countries, epidemics of diseases caused by bacterial pathogens remain widespread. The major disadvantage of using indicators is during the microbiological determination of water quality. The methods used for microbiological determinations are based on detecting organisms (coliform bacteria) which are indicative of the presence of faecal pollution. If evidence of faecal material in the water is detected, it is assumed that pathogens may be present (DWAF et al., 2001). By the time pathogens can be detected, there is a strong possibility that water containing these pathogens has already been consumed and disease may therefore have been initiated. This approach would therefore limit the potential for preventative action to be taken (Chapman and Hall, 1992). Reliance on end product testing is risky because it gives limited warning of water quality deterioration and therefore impedes the implementation of preventative actions.
3
Source: DWAF et al., 2001
Figure 1: Constituents that must be measured at different points in the supply system
when assessing water quality
1.4 BENEFITS OF USING THE WATER SAFETY PLAN Water safety plans (WSPs) are a form of water quality assurance through a multi-barrier concept (WHO2). The multiple barrier principle implies that actions are required at all stages in the process of producing and distributing water in order to protect water quality. This includes source protection, treatment (when applied) through several different stages, prevention of contamination during distribution (piped or non-piped) and maintenance within households. The role of indicators is seen as primarily being a means of verification of the WSP in meeting water quality objectives rather than as a routine tool for monitoring water quality (WHO2). A WSP provides an organised and structured system to minimizethe chance of failure through oversight or management lapse. The process provides consistency with which safe water is supplied and provides contingency plans to respond to system failures or unforeseeable hazardous events. Water safety plans can be developed generically for small supplies rather than for individual supplies.
Group B
Nitrate/nitrite Fluoride Sulphate Chloride Arsenic Total coliforms The presence/concentration of these substances should be measured before water is supplied as they may lead to health problems. Frequency of testing is dependent on the source, treatment applied and the population served.
Group A
Conductivity Faecal coliforms pH Turbidity Free chlorine These are indicators of potential problems and should be frequently tested at all points in the water supply system. Free chlorine can be measured only once water has been treated with chlorine-based disinfectants.
Group D
Manganese Zinc Iron Potassium Sodium Magnesium Calcium Hardness
Substances that are commonly present that cause aesthetic or
economic concern only. Should be measured when assessing water
quality for the first time or when there is reason to believe that water quality
has changed.
Group C
Cadmium Copper These substances occur less frequently but may lead to health problems. (Should be tested at point of use).
4
A Water Safety Plan includes three key components (WHO2): System assessment – determines whether the drinking water supply chain (up to the point
of consumption) as a whole can deliver water of a quality that meets health-based targets. Identifying control measures in a drinking water system that will collectively control identified
risks and ensure that health based targets are met For each control measure identified, an appropriate means of operational monitoring should be defined that will ensure that any deviation from the required performance is rapidly detected in a timely manner.
Management plans describing actions taken during normal operation or incident conditions and documenting the system assessment (including upgrade and improvement), monitoring and communication plans and supporting programmes.
The WSP will guide both day to day actions and long term planning. It will identify crucial aspects that collectively ensure the provision of safe water and aid system managers and operators in gaining a better understanding of the water supply system and the risks that need to be managed (WHO2). Some of these aspects include: regular monitoring and inspections that signal deteriorating water quality (and prompt action) regular on-going maintenance to reduce the chance of failure by contamination guidance for improvement and expenditure additional training and capacity building initiatives a list of where to get help, who needs to know details of water quality, and how quickly they
need to know A diagram of the steps involved in conducting an assessment based on the WSP approach is presented in Figure 2.
Figure 2: Steps used to guide an assessment of water supply based on the WSP approach
This document is a guideline that focuses on the methodology that can be used to develop a water safety plan for small community water supply in South Africa. A comprehensive checklist has also been included to ensure the proper development and maintenance of a Water Safety Plan.
STEP ONE STEP TWO STEP THREE
Risk Management
Control measures applied.
Operational monitoring.
Management procedures (corrective actions and incident/emergency response).
Supporting programmes.
Record keeping and documentation.
Validation and verification.
Water supply system assessment
Team assembled to conduct WSP.
Intended use of water established.
Risk assessment Hazard identification
(biological., chemical., physical or radiological) from source to consumer.
Hazardous event identification.
Risk of hazard causing harm to population.
5
SECTION 2: METHODOLOGY ON HOW TO DEVELOP A WATER SAFETY PLAN
The World Health Organisation (WHO2) has outlined steps on how to conduct the WSP. This section incorporates these basic principles as well as additional information obtained during a literature review of various other WSPs that have already been established in other countries. 2.1 ASSEMBLE A TEAM TO CARRY OUT THE WATER SAFETY PLAN The institutional framework for the provision of potable water in South Africa is outlined below. A collaborative multi-stakeholder approach is required as it will ensure that all the agencies with responsibility for specific areas within the water cycle are involved in the management of water quality.
National government (DWAF*, DoH**, DoE***)
Provincial government
Local government
(Water Service Providers, Water Service Authorities including local and district municipalities)
Water users
(Commercial and private users)
* Department of Water Affairs and Forestry ** Department of Health *** Department of Education
Figure 3: Institutional framework for the provision of potable water in South Africa A multidisciplinary team of experts with a thorough understanding of the drinking water system is assembled. These individuals are involved in each stage of the drinking water supply and include: engineers catchment and water managers water quality specialists environmental., public health or hygiene professionals operational staff of treatment plants consumer representatives A senior member of the team is appointed to help guide and direct the team through the preparation of the water safety plan and the assessment of the system. The team leader must have the authority, organizational skills and interpersonal skills to ensure that the project can be implemented. The team’s responsibility is to define the scope of the water safety plan that will include which part of the water supply chain is involved and the general classes of hazards to be addressed. The size of the team will vary between the different types of water suppliers and in some instances it may be useful to identify sub-teams to take lead in specific activities. Operational staff involvement is essential as they often have the greatest knowledge about problems in the supply system. In situations where the required skills are unavailable locally, the team leader should seek external support.
6
2.2 DOCUMENT AND DESCRIBE THE SYSTEM A complete understanding of the system including the range and magnitude of hazards that may be present and the ability of existing processes and infrastructure to manage actual or potential risks is essential. In order to accomplish this successfully, it is necessary to document and describe the system. During this process, various factors for each step in the water supply system must be considered. These factors are listed in Table 1. Table 1: Factors for consideration during the documentation and description of the system
Source water and catchment Treatment Distribution system Capacity of the source in relation to demand Protection measures applied Developments in the catchments that affect quality Known water quality problems
Processes applied Number of individual units Age of plant Known design faults
Number of service reservoirs Volume of these reservoirs Age of reservoir Known design faults Area/s of distribution and population served Known operational problems
Source: Godfrey and Howard, 2004 The next stage is to define the intended use of water, i.e. will the water be used for domestic, industrial or agricultural use. It will also address the susceptibility of the end users and attempt to identify particularly vulnerable sub-groups that may be at particular risk. The description of the intended use of water should also include (Godfrey and Howard, 2004): The numbers of people served. Socio-economic status of people served. Intended use of water and the relevant exposure routes. Consumer education available for water use and how this is communicated, including how
consumers are notified of potential contamination. Special considerations are required for vulnerable groups such as infant, elderly and immuno-
compromised. 2.3 ASSESS THE EXISTING PROPOSED SYSTEM (INCLUDING A
DESCRIPTION OF THE PROCESS AND A FLOW DIAGRAM) A flow diagram of the water supply system must be constructed. It will provide an overview description of the drinking water system and will enable hazards to be identified clearly. The flow diagram will contain: Characterization of the source. Identification of potential pollution sources in the catchment. Measures of resource and source protection. Treatment processes. Storage and distribution infrastructure. A symbol chart for each step of the water supply system has been designed to provide consistency when drawing the flow diagram. These are given below (Figure 4) with an example of how a flow diagram should be drawn (Figure 5). It is important to ensure that the representation of the drinking water system is conceptually accurate as it is possible to overlook potential hazards that may be significant. In order to achieve this, confirmation of the flow diagram is required. If the flow diagram is inaccurate the team will not consider appropriate control measures for any hazards that were overlooked. A common method of validating a flow diagram is to pay a visit to the system and confirm the set up of the system and processes. Validation of the flow diagram is also beneficial in determining the vulnerability of the system in terms of its design and construction (refers to aspects that are
7
unlikely to change unless a rehabilitation programme is initiated) and the operation and maintenance of the system (those changes that are likely to occur rapidly and unpredictably). Proof of the flow chart validation must be signed and dated by a team member and documented thereafter.
Water source Ground □ Surface ⊠
Raw water storage reservoir
Open ◫ Closed ⊟
Pre-treatment Fluoride, iron and manganese, taste and odour removal., disinfection, etc. ⊞
Main treatment processes
Coagulation ⊘ Flocculation ⊗
Sedimentation ⊖ Filtration ⊕
pH adjustment Lime, CO2, soda ash
Disinfection
Chlorine gas, Cl2, chloramination, ozone, UV, HTH ◬
Distribution
On site service reservoir/s ▧ Off site service reservoir/s ▨
Booster stations ⊡ Valves ⋈
Consumer
Pipes (urban/semi-urban) ⊜ Stand pipes and house connections ⌂
Figure 4: Symbol chart for drawing flow diagrams of water treatment systems
⊠ Surface water from catchment (upstream)
↓
⊞ Pre-treatment (disinfection Cl2 and UV)
↓
◫ Downstream harvesting storage
↓
◬ pH adjustment, disinfection (lime, Cl2 gas)
↓
⊜ Urban pipes
▨ ▨ Closed service reservoirs
↓
⊡ Booster station
(2o chloramination) ↓ ⌂ ⌂
House connections
Figure 5: An example of a flow diagram for a system
8
2.4 UNDERTAKE A HAZARD ASSESSMENT AND A RISK CHARACTERIZATION TO IDENTIFY AND UNDERSTAND HOW HAZARDS CAN ENTER INTO THE WATER SUPPLY
2.4.1 Identifying Hazards A hazard is any agent that will cause an adverse health effect if it is consumed via drinking water. A hazardous event is an incident or situation that can lead to the presence of a hazard. Hazards may be microbiological, physical or chemical in origin. Identification of hazards is important to ensure that adequate protection measures can be applied and to identify treatment requirements. At each step the intention is to determine what could happen that could lead to contamination, and the associated control measures for each hazard. Once hazard/s have been identified, consideration of the events that lead to their entry into the drinking water supply system is required. An easier way of developing an understanding of hazards is to determine the possible sources rather than trying to mark out specific hazards. Sources of potential hazards or hazardous events can be found in each step of the water supply system. These are listed in Table 2. The impact of the hazard can be characterised by assessing the severity of the likely health outcome (in terms of the impact and population affected) and the probability of occurrence. 2.4.2 Prioritizing Hazards A risk is the likelihood of the identified hazard/s causing harm to exposed populations in a specified timeframe including the magnitude of that harm and/or the consequences. In any system there may be a number of hazards (Table 2) and a large number of control measures. It is therefore important to rank hazards in order to establish priorities. The hazard assessment matrix in Table 3 (WHO2) is a guide to scoring the existing risks that could make water unsafe. Likelihood is determined by “how often’ or “how likely” a hazard or a hazardous event occurs. It must take into account hazards that have occurred in the past and their likelihood of re-occurrence and must also predict the likelihood of hazards and events that have not occurred to date. Consequence determines the severity of the results of the hazard/hazardous event and the seriousness or intensity of the impact of the hazard to human health.
RISK RATING = LIKELIHOOD CONSEQUENCE Multiplying the derived likelihood ratings with derived consequence ratings from the risk assessment matrix produces a risk rating. E.g. a likelihood rating of 0.8 multiplied by a consequence rating of 70 would give a risk rating of 0.8 70 = 56, which would be ranked higher than an event with a likelihood of 0.2 and a consequence of 2 and a risk rating of 0.2 2 = 0.4. A higher score implies that a bigger risk of a hazardous event occurring exists and should therefore be prioritised. A risk profile based on the calculated score is given in Table 4.
9
Table 2: Sources of potential hazards or hazardous events in the water supply system
ELEMENTS OR PROCESSES OF A DRINKING WATER
SYSTEM
POTENTIAL HAZARDS OR HAZARDOUS EVENTS
Source Water: Surface
On-site septic tank systems Domestic waste dumping Land spreading of manure Feedlot runoff Municipal sewage effluent Heavy metal., pharmaceutical residuals Municipal landfills Industrial activities Leaking pipelines Pesticide use Petroleum refineries Highway, railway accidents and spills Recreational activities Natural events – flooding, droughts, etc.
Source Water: Ground
On-site septic systems Domestic waste dumping Municipal landfills Graveyards Land spreading of manure Intensive livestock activities Gas service stations – hydrocarbon contamination Industrial plants Leaking pipelines – hydrocarbon contamination Sludge disposal areas and petrol refineries Highway/railway accidents and spills
Treatment systems
Water optimization – failure Coagulant dosing – failure Filtration – failure Coagulation, flocculation and sedimentation – biofilm growth Inlet flow control – failure pH correction – inappropriate levels Disinfection – under/over dose Reservoir storage – contamination
Distribution
Reservoirs – security control failure Pump stations – security control failure Distribution transmission mains – geological faults Distribution water mains – geological faults Re-chlorination points – under or over dosage Main breaks – contamination of mains Cross section with sewage pipes (microbial hazard)
Other water delivery systems
Tank truck storage – loss of sterile conditions Tank truck previous use – contamination Cisterns – contamination
Source: CWWA, 2005
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Table 3: Risk Assessment Matrix
LIKELIHOOD RATING CONSEQUENCE RATING Almost certain
(once a day or permanent feature) 1
Catastrophic (Death expected from exposure)
100
Likely (once per week)
0.8 Major
(Population exposed to significant illness)
70
Moderately likely (once per month)
0.5 Moderate
(Large aesthetic impact) 20
Unlikely (once per year)
0.2 Minor
(Small aesthetic impact) 2
Rare (1 in 5 years)
0.1 Insignificant (No impact)
1
Table 4: Risk profile based on score calculated from risk assessment matrix
SCORE RISK PROFILE
0-10 Low
These are systems that operate with minor deficiencies. Usually the systems meet the water quality parameters specified by the appropriate guidelines (SANS 241:2006).
11-56
Medium These are systems with deficiencies which individually or combined pose a high risk to the quality of water and human health. These systems would not generally require immediate
action but the deficiencies could be more easily corrected to avoid future problems.
57-100
High These are systems with major deficiencies which individually combined pose a high risk to the quality of water and may lead to potential health and safety or environmental concerns. Once systems are classified under this category, immediate corrective action is required to
minimizeor eliminate deficiencies. 2.5 IDENTIFY CONTROL MEASURES – THE MEANS BY WHICH RISKS CAN
BE CONTROLLED 2.5.1 Identifying Control Measures Control measures are actions that reduce levels of hazards within water supply systems either by preventing entry, reducing concentration, or by restricting their production. Many control measures are effective against more than one specific hazard while some hazards may require more than one control measure for effective control. The assessment and planning of control measures should ensure that health-based targets will be met and should be based on hazard identification and assessment. Identification and implementation of control measures needs to be based on a multi-barrier principle so that if one barrier fails, the remaining barriers will still operate, thus minimizing the likelihood of contaminants passing through the entire system and being in sufficient amounts to cause harm to consumers. Some control measures are actions at specific points in the system and are referred to as control points. Defining control points is an important component of the water safety plan and provides water utilities with information regarding where specific actions need to be taken to ensure water safety. Control points should not be the only focus of water utilities to ensure water supply as a collective and preventative approach is required.
11
The prioritization of control measures and points must be related to the severity of the potential risk. Control points identified as being of higher priority are therefore monitored more frequently to ensure that there is compliance. For each control measure, critical limits should be defined. Critical limits are the performance targets that, when exceeded, compromise the quality of water being supplied. Critical limits define when the control measure is out of compliance and action is required. It is essential that critical limits be directly or indirectly measurable. SANS 241 provides critical limits for various constituents in the water matrix. Limits will be indicators that can be readily interpreted at the time of monitoring and where actions can be taken in response to non-compliance. Critical limits are defined so that they do not automatically lead to a breakthrough of pathogens into the water supply, but signal that actions are required urgently to prevent an unacceptable level of risk occurring. Control measures should be identified for each step in the water supply. Some important factors that need to be considered are listed in Table 5 (WHO2).
12
Tab
le 5
: F
acto
rs f
or
con
sid
erat
ion
RE
SO
UR
CE
AN
D S
OU
RC
E
PR
OT
EC
TIO
N
SO
UR
CE
WA
TE
R A
ND
C
AT
CH
ME
NT
S
WA
TE
R A
BS
TR
AC
TIO
N
AN
D S
TO
RA
GE
SY
ST
EM
WA
TE
R T
RE
AT
ME
NT
S
YS
TE
M
DIS
TR
IBU
TIO
N S
YS
TE
MS
D
evel
opin
g a
cat
chm
ent
man
agem
ent
pla
n w
hich
in
clud
es c
ontr
ol m
easu
res
to p
rote
ct s
urfa
ce a
nd
grou
nd w
ater
s
Ens
urin
g th
at
plan
ning
re
gula
tions
incl
ude
prot
ectio
n of
wat
er
reso
urce
s fr
om p
oten
tially
po
llutin
g ac
tiviti
es (
e.g.
in
dust
ries)
Pro
mot
ing
awar
ene
ss in
co
mm
uniti
es o
f th
e im
pact
of
hum
an a
ctiv
ities
on
wat
er q
ual
ity
D
esig
nate
d an
d lim
ited
uses
Reg
istr
atio
n of
che
mic
als
used
in th
e ca
tchm
ents
Spe
cific
pro
tect
ive
requ
irem
ents
(e.
g.
cont
ainm
ent)
for
a ch
emic
al in
dust
ry o
r re
fuel
ing
stat
ions
Con
trol
of h
um
an
activ
ities
with
in t
he
catc
hmen
t ar
ea
C
ontr
ol o
f was
tew
ater
ef
fluen
ts
R
egul
ar in
spec
tion
of
catc
hmen
t ar
ea
La
nd u
se p
lann
ing
proc
edu
res
– us
e of
pl
anni
ng
and
en
viro
nmen
tal r
egul
atio
ns
to r
egul
ate
pot
entia
l wat
er
pollu
ting
deve
lopm
ents
Div
ersi
on o
f st
orm
wat
er
flow
s
Run
-off
inte
rcep
tion
U
se o
f ava
ilabl
e w
ater
st
orag
e du
ring
and
afte
r pe
riods
of h
eav
y ra
infa
ll
App
rop
riate
loca
tion
and
prot
ectio
n of
inta
ke
A
ppro
pria
te c
hoic
e of
off-
take
dep
th fr
om r
eser
voir
s
Pro
per
wel
l pro
tect
ion
syst
ems
S
tora
ge a
rea
s an
d re
serv
oirs
sho
uld
cont
ain
roof
s
Acc
ess
to s
tora
ge
area
s sh
ould
be
rest
ricte
d fr
om
anim
als/
bird
s, e
tc.
C
oag
ulat
ion/
flocc
ulat
ion/
sed
imen
tatio
n/fi
ltrat
ion
A
ltern
ativ
e tr
eatm
ent
U
se
of
app
rove
d w
ater
tr
eatm
ent
chem
ical
s an
d
mat
eria
ls
C
ontr
ol
of
wat
er
trea
tmen
t ch
emic
als
P
roce
ss
cont
rolla
bilit
y of
eq
uipm
ent
Ava
ilabi
lity
of
back
-up
syst
ems
W
ater
tre
atm
ent
proc
ess
optim
izat
ion
incl
udin
g:
chem
ical
do
sing
, fil
ter
back
was
hing
, flo
w
rate
, m
inor
in
fras
truc
ture
m
odifi
catio
ns
U
se
of
tank
st
orag
e in
pe
riods
of h
eav
y ra
infa
ll
D
istr
ibut
ion
syst
em
mai
nten
ance
Ava
ilabi
lity
of b
ack-
up
syst
ems
M
aint
aini
ng a
n ad
equ
ate
disi
nfec
tant
res
idua
l co
ncen
trat
ion
C
ross
con
nect
ion
and
back
-flo
w p
reve
ntio
n de
vice
s im
plem
ente
d
F
ully
enc
lose
d di
strib
utio
n sy
stem
s an
d st
orag
e fa
cilit
ies
A
ppro
pria
te r
epai
r pr
oced
ure
s in
clud
ing
subs
eque
nt d
isin
fect
ion
of
wat
er m
ains
Mai
ntai
ning
ade
qua
te
syst
em p
ress
ure
Sou
rce:
WH
O2
13
2.5.2 Defining Corrective Actions for Each Control Measure For each control measure, corrective actions should be determined and adhered to as soon as critical limits have been exceeded. This is an important component of the management aspects of the Water Safety Plan and should be effective in restoring performance to acceptable levels when critical limits are exceeded. Corrective actions may include a wide range of actions, e.g. the ability to change temporarily to an alternate water source, the use of back-up disinfection plants or spot dosing. Corrective actions must be supported by a contingency plan. This plan is a detailed management response to failures and will identify individual responsibilities and a time constraint for remedy. Corrective actions should also include long term actions designed to prevent non-compliance and reduce the need for contingency plans to be re-actioned. This may require defining/identifying new control measures and will be linked to on-going investment plans. A range of suggested corrective actions (NMHRC, 2005) for various hazards has been included in Annexure B. 2.6 DEFINE MONITORING OF CONTROL MEASURES – WHAT LIMITS
DEFINE ACCEPTABLE PERFORMANCE AND HOW THESE ARE MONITORED
Monitoring is the act of conducting a planned series of observations or measurements of operational and/or critical limits to assess whether the components of the water supply are operating properly. The objectives of operational monitoring are for the drinking water supplier to monitor each control measure in a timely manner to enable effective system management and to ensure that health-based targets are achieved. The parameters selected for operational monitoring should: reflect the effectiveness of each control measure provide a timely indication of performance be readily measured provide opportunity for an appropriate response Control measures should be closely monitored, especially in the early stages of the WSP, in order to ensure that any problems that have been identified are rectified timeously. The strategies and procedures for monitoring the various aspects of the water supply system should be documented. Monitoring plans should include the following: Parameters to be monitored. Sampling location and frequency. Sampling needs and equipment. Schedules for sampling. Methods for quality assurance and validation of sampling results. Responsibilities and necessary qualifications of staff. Requirements for documentation and management of records including how monitoring of
results will be recorded and stored. Requirements for reporting and communication of results. Frequency of operational monitoring is generally dependent on population size. Table 6 lists the suggested sampling types and frequencies based on population served (SANS 241:2006).
14
Table 6: Suggested sampling types and frequencies based on population served
POPULATION SERVED 0-
2500 2501-10000
10001-25000
25001-100000
>100001
FREQUENCY (NUMBER OF SAMPLES PER YEAR)
12 24 36 120 120 every year per
100000 of population served
Physical and organoleptic requirements Colour 1 1 4 12 12 Conductivity at 25°C 12 24 36 120 365 Dissolved solids 1 1 4 12 12 Odour 12 24 36 120 365 pH value at 25°C 12 24 36 120 365 Taste 12 24 36 120 365 Turbidity 12 24 36 120 365 Chemical determinands Ammonia as N 1 1 4 12 12 Calcium as Ca 1 1 4 12 12 Chloride as Cl 1 1 4 12 12 Fluoride as F 1 1 4 12 12 Magnesium as Mg 1 1 4 12 12 Nitrate and nitrite as N 1 1 4 12 12 Potassium as K 1 1 4 12 12 Sodium as Na 1 1 4 12 12 Sulphate as SO4 1 1 4 12 12 Zinc as Zn 1 1 1 4 4 Aluminium as Al 1 1 4 12 12 Antimony as Sb 1 1 1 4 4 Arsenic as As 1 1 1 4 4 Cadmium as Cd 1 1 1 4 4 Chromium as Cr 1 1 1 4 4 Cobalt as Co 1 1 1 4 4 Copper as Cu 1 1 1 4 4 Cyanide (recoverable) as CN
1 1 1 4 4
Iron as Fe 1 1 4 12 12 Lead as Pb 1 1 1 4 4 Manganese as Mn 1 1 4 12 12 Mercury as Hg 1 1 1 4 4 Nickel as Ni 1 1 1 4 4 Selenium as Se 1 1 1 4 4 Vanadium as V 1 1 1 4 4 Organic determinands Dissolved organic carbon as C
1 1 1 4 4
Total trihalomethanes 1 4 4 12 12 Phenols 1 1 1 4 4 Microbiological determinands E. coli 12 24 36 120 365 Permanent records of the results of monitoring and documented monitoring plans should be maintained. If monitoring shows that a critical limit has been exceeded, the potential for water to be unsafe is increased and requires that immediate action be taken.
15
2.7 ESTABLISH PROCEDURES TO VERIFY THAT THE WATER SAFETY PLAN IS WORKING EFFECTIVELY AND WILL MEET THE HEALTH-BASED TARGETS
Verification, in addition to operational monitoring of the performance of the individual components of a drinking water system, is necessary to ensure that the system as a whole is operating safely. Verification may be undertaken by the Water Service Provider, the Water Service Authority, an independent authority or by a combination of these. Verification provides a mechanism by which the water supplier and surveillance body are able to check whether the system is delivering water that meets safety requirements. Verifying performance requires assessment of a range of performance indicators. Verification will involve both operational audit and water quality analyses using a range of index organisms. Operational audit should include the systematic review of operational procedures and documentation to ensure that the WSP is working. During the audit, operational records of all treatment processes and distribution system maintenance should be reviewed to assess whether they exhibit the requirements for each component of the system. In addition, spot checks in the field should be carried out. A key element of the audit process is to identify when monitoring results show deviation from critical limits and what operational shortcomings may have been the cause. The audit should identify shortcomings in the overall WSP and identify modifications and improvements required for the WSP. 2.8 DEVELOP SUPPORTING PROGRAMMES Many actions are important in ensuring drinking water safety but do not directly affect drinking water quality and are therefore not control measures. These are referred to as supporting programmes and should be documented in a WSP. Supporting programmes are activities that ensure the operating environment, equipment used and the people themselves do not become an additional source of potential hazards to the drinking water supply. Supporting programmes could specifically involve: Control and access of people onto treatment plants, catchments and reservoirs and
implementation of the appropriate security measures to prevent transfer of hazards from people when they do enter source water.
Development of verification protocols for the use of chemicals and materials used in water supply (for suppliers to partake in international quality assurance programmes).
Designated equipment for attending to incidents (e.g. main bursts) and equipment used for sewage water should not be used for potable water.
Training and educational programmes for personnel involved in activities that could influence water safety. Training should be implemented as part of induction programmes and frequently updated.
Codes of good operating, management and hygienic practice are essential elements of supporting programmes. These are often captured within standard operating procedures (SOPs) and include: Hygienic working practices documented in maintenance SOPs. Training and competence of personnel involved in water supply. Tools for managing the actions of staff such as quality assurance systems. Securing stakeholder commitment at all levels to the provision of safe water. Education of communities whose activities influence water quality. Calibration and monitoring of equipment. Record keeping.
16
Comparison of supporting programmes with those of others through peer review, benchmarking and personnel or document exchange can encourage ideas for improved practice. 2.9 PREPARE MANAGEMENT PROCEDURES Effective management involves actions to be taken in response to variations that occur during “normal” operating conditions and “incident” situations where the loss of a control system may occur, and of procedures to follow in unforeseen and emergency situations. Management plans should be documented alongside system assessment, monitoring plans, supporting programmes and communication required to ensure safe operating of the system. Emergency response plans should clearly specify responsibilities for co-ordinating measures to be taken, a communication plan to inform/alert users of supply and plans for providing/distributing emergency supplies of water. Key areas to be addressed in emergency response plans include: Response actions – including increased monitoring. Plans for emergency water supplies. Responsibilities and authorities internal and external to the organization. Communication strategies and protocols including notification procedures (internal, regulatory
body, media, public). Mechanisms for increased public health surveillance. The DWAF DWQ Framework (2007) has identified alert levels based on the public health risk and aesthetic quality to respond to acute drinking water failure. Three Alert Levels are proposed to respond to acute drinking water quality failures: Alert Level I (Drinking Water Incident – no significant risk to health): Routine problems
including minor disruptions to the water system and single sample non-compliances. Alert Level II (Drinking Water Failure – potential minor risk to health): Minor emergencies,
requiring additional sampling, process optimisation and reporting/ communication of the problem.
Alert Level III (Drinking Water Emergency – potential major risk to health): Major emergencies requiring significant interventions to minimizepublic health risk (Engagement of a designated Emergency Management Team).
Tables 7 and 8 below indicate the classification of Alert Level concentrations for both health related and aesthetic variables and the required actions.
17
Tab
le 7
: In
cid
ent
Man
agem
ent
Pro
toco
l fo
r H
ealt
h R
elat
ed D
rin
kin
g W
ater
Qu
alit
y In
cid
ents
Cla
ssif
ic-
atio
n o
f In
cid
ent
Wat
er Q
ual
ity
Co
nst
itu
ent
and
Co
nce
ntr
atio
n
Hea
lth
imp
licat
ion
/ris
k In
cid
ent
Man
age-
men
t
Req
uir
edR
esp
on
se
Tim
e A
cti
on
Ale
rt L
eve
l I
(Drin
king
W
ater
Q
ualit
y In
cide
nt)
1
E. c
oli p
er 1
00
mL
1
Col
iph
age
per
10 m
L
A
ny
hea
lth-r
ela
ted
phys
ical
or
che
mic
al r
esul
t tha
t ex
cee
ds th
e up
per
limit
of
SA
NS
241
: 20
06 D
rink
ing
Wat
er C
lass
I lim
it
In
sign
ifica
nt c
han
ce o
f inf
ectio
n.
V
ery
slig
ht r
isk
of v
iral i
nfec
tion
with
con
tinu
ous
expo
sure
.
Insi
gnifi
cant
ris
k to
hea
lth –
su
itab
le fo
r lif
etim
e co
nsum
ptio
n.
Inte
rnal
Within 24 hrs of result release
C
omm
unic
ate
out-
of-r
ange
res
ult t
o re
leva
nt m
unic
ipa
l st
aff;
A
sses
s as
soci
ated
info
rmat
ion
and
impl
eme
nt c
orre
ctiv
e ac
tion
to r
ectif
y th
e in
cid
ent o
r re
sam
ple
to c
onfir
m r
esul
t if
requ
ired;
If re
sam
ple
resu
lt co
nfirm
s th
e in
itial
res
ult,
impl
eme
nt
corr
ectiv
e ac
tion
to r
ectif
y th
e in
cid
ent;
If
resa
mpl
e re
sult
exc
eeds
the
con
cent
ratio
ns s
peci
fied
in
Ale
rt L
eve
l I, p
roce
ed
to A
lert
Lev
el I
I.
Ale
rt L
evel
II
(Drin
king
W
ater
Q
ualit
y F
ailu
re)
2-
10 E
. col
i per
100
mL
2-10
Col
iph
age
s pe
r 10
mL
1 C
rypt
ospo
ridiu
m o
r G
iard
ia c
yst p
er
10 L
Tur
bidi
ty r
esul
t >
5 N
TU
Flu
orid
e re
sult
0.9-
1.7
mg/
L
C
linic
al in
fect
ions
unl
ikel
y in
he
alth
y ad
ults
, but
ma
y oc
cur
in
sens
itive
gro
up
s.
Lo
w r
isk
of v
iral i
nfec
tion
with
co
ntin
uous
exp
osur
e.
Lo
w r
isk
of p
roto
zoa
n pa
rasi
te
infe
ctio
n.
In
dire
ct a
ssoc
iate
d im
pac
ts o
n he
alth
thro
ugh
the
shi
eld
ing
of
bact
eria
from
dis
infe
ctio
n.
S
light
mot
tling
of d
enta
l ena
mel
.
Inte
rnal
an
d E
xter
nal
Same day as result release
R
eque
st a
ddi
tiona
l mon
itori
ng
as r
equ
ired
(bot
h sp
atia
lly
and
incr
ease
d fr
eque
ncy)
to e
stab
lish
the
sour
ce o
f the
co
ntam
inat
ion
and
the
risk
to p
ublic
he
alth
;
Ass
ess
trea
tmen
t pro
cess
effi
cien
cy a
nd im
ple
me
nt
corr
ectiv
e ac
tion
to o
ptiim
izet
he
trea
tmen
t pro
cess
;
Com
mun
icat
e th
e dr
inki
ng
wat
er fa
ilure
an
d h
ealth
ris
k to
th
e re
leva
nt m
unic
ipa
l sta
ff, D
WA
F a
nd D
oH;
If
any
addi
tiona
l sam
ple
resu
lts e
xcee
d co
ncen
trat
ions
sp
ecifi
ed in
Ale
rt L
evel
II,
proc
eed
to A
lert
Lev
el I
II.
18
Cla
ssif
ic-
atio
n o
f In
cid
ent
Wat
er Q
ual
ity
Co
nst
itu
ent
and
Co
nce
ntr
atio
n
Hea
lth
imp
licat
ion
/ris
k In
cid
ent
Man
age-
men
t
Req
uir
edR
esp
on
se
Tim
e A
cti
on
Ale
rt L
evel
III
(Drin
king
W
ater
Q
ualit
y E
mer
genc
y)
>
10 E
. col
i per
100
mL
>10
Col
iph
age
s pe
r 10
mL
>1
Cry
ptos
porid
ium
or
Gia
rdia
/10
L
A
ny
hea
lth-r
ela
ted
Ph
ysic
al
or C
hem
ical
re
sult
that
ex
cee
ds th
e up
per
limit
of
SA
NS
241
: 20
06 D
rink
ing
Wat
er C
lass
II li
mit
(with
in
exce
ptio
n of
turb
idity
)
Flu
orid
e re
sult
>1.
7 m
g/L
C
linic
al in
fect
ions
com
mon
, eve
n w
ith o
nce-
off c
onsu
mpt
ion.
Sig
nifi
cant
and
incr
easi
ng r
isk
of
infe
ctio
us d
ise
ase
tran
smis
sion
.
Sig
nifi
cant
ris
k of
pro
tozo
an
para
site
infe
ctio
n.
S
ign
ifica
nt r
isk
to h
uman
hea
lth
–ma
xim
um a
llow
abl
e lim
its
exce
ede
d.
S
ever
e to
oth
dam
age
and
skel
eta
l flu
oros
is w
ith lo
ng-t
erm
ex
posu
re.
Inte
rnal
an
d E
xter
nal
Immediate
E
nga
ge E
mer
gen
cy M
anag
em
ent T
eam
;
Com
mun
icat
e dr
inki
ng w
ater
em
erg
ency
an
d he
alth
ris
k to
re
leva
nt m
unic
ipal
sta
ff, D
G o
f DW
AF
, hea
d of
pro
vinc
ial
DoH
;
Con
tinue
add
ition
al m
onito
rin
g an
d e
xten
d to
the
dist
ribut
ion
syst
em a
nd p
oin
t-of
-use
to e
stab
lish
the
sour
ce
and
ext
ent
of t
he in
cide
nt a
nd th
e ris
k to
pub
lic h
ealth
;
Ass
ess
the
com
mun
ities
at r
isk
and
the
nee
d fo
r an
al
tern
ate
wat
er s
uppl
y;
C
omm
unic
ate
drin
king
wat
er e
mer
gen
cy to
com
mun
ity;
Im
plem
ent
spe
cial
ist p
roce
ss a
sses
sme
nt a
nd
optim
isat
ion
of th
e dr
inki
ng w
ater
sup
ply
syst
em fr
om c
atch
men
t to
cons
umer
;
Pha
se o
ut a
dditi
ona
l mon
itori
ng
once
the
sou
rce
of th
e in
cid
ent h
as b
een
iden
tifie
d an
d re
ctifi
ed a
nd t
wo
cons
ecut
ive
resu
lts h
ave
bee
n w
ithin
spe
cific
atio
n;
P
repa
re n
otifi
catio
ns a
dvis
ing
of t
he e
nd o
f the
em
erge
ncy;
Ass
ess
requ
ired
prev
ent
ativ
e ac
tion
to r
educ
e th
e lik
elih
ood
of th
e in
cide
nt r
ecu
rrin
g;
P
repa
re a
rep
ort
to d
ocum
ent a
nd c
lose
the
inci
den
t;
Rev
iew
an
d up
date
Inci
den
t M
ana
gem
ent
Pro
toco
l;
Ret
rain
sta
ff on
rev
ised
Inci
dent
Man
agem
en
t Pro
toco
l. In
the
case
of a
fluo
ride
ove
rdos
e in
exc
ess
of 1
0 m
g/L,
the
Dire
ctor
-Ge
ner
al o
f the
De
par
tmen
t of H
ealth
is a
lso
requ
ired
to b
e in
form
ed
(Sch
edul
e of
Reg
ula
tions
on
Flu
orid
atin
g W
ater
Sup
plie
s u
nder
Nat
ion
al H
ealth
Act
(N
o. 6
1 of
200
3)).
19
Tab
le 8
: In
cid
ent
Man
agem
ent
Pro
toco
l fo
r A
esth
etic
Dri
nki
ng
Wat
er Q
ual
ity
Inci
den
ts
Cla
ssif
ic-
atio
n o
f In
cid
ent
Wat
er Q
ual
ity
Co
nst
itu
ent
and
C
on
cen
trat
ion
A
es
thet
ic im
plic
atio
n/r
isk
Inci
den
t M
anag
e-m
ent
Req
uir
edR
esp
on
se
Tim
e A
cti
on
Ale
rt L
eve
l I
(Inc
iden
t)
G
eosm
in o
r 2-
MIB
5-
10 n
g/L
Iron
0.2
-1.0
mg
/L
M
ang
anes
e 0.
1-0.
4 m
g/L
M
oder
ate
unpl
easa
nt
tast
es/o
dour
s.
S
light
tast
e an
d co
lour
, slig
ht
stai
ning
of
whi
te c
loth
es
S
light
tast
e an
d co
lour
, mod
era
te
stai
ning
of c
loth
es a
nd
fixtu
res
Internal
Within 24 hrs of result release
C
omm
unic
ate
out-
of-r
ange
res
ult
to r
elev
ant
mun
icip
al s
taff;
Ass
ess
asso
ciat
ed in
form
atio
n an
d im
plem
ent
cor
rect
ive
actio
n to
rec
tify
the
inci
den
t or
resa
mpl
e to
con
firm
res
ult
if re
quire
d;
If
resa
mpl
e re
sult
conf
irms
the
initi
al r
esul
t, im
plem
ent
co
rrec
tive
actio
n to
rec
tify
the
inci
den
t;
If re
sam
ple
resu
lt e
xcee
ds th
e c
once
ntra
tions
spe
cifie
d in
A
lert
Lev
el I
, pro
cee
d to
Ale
rt L
eve
l II.
A
lert
Lev
el I
I (F
ailu
re)
G
eosm
in o
r 2-
MIB
11-
20 n
g/L
Iron
1.1
-2.0
mg
/L
M
ang
anes
e 0.
5-1.
0 m
g/L
M
oder
ate
unpl
easa
nt
tast
es/o
dour
s
Mod
erat
e ta
ste
and
col
our,
m
oder
ate
stai
nin
g of
wh
ite c
loth
es
M
oder
ate
tast
e a
nd c
olou
r,
incr
eas
ing
stai
nin
g of
clo
thes
and
fix
ture
s
Internal and External
Same day as result release
R
eque
st a
ddi
tiona
l mon
itori
ng
as r
equ
ired
(bot
h sp
atia
lly
and
incr
ease
d fr
eque
ncy)
to e
stab
lish
the
sour
ce o
f the
co
ntam
inat
ion
and
the
aest
hetic
impa
ct;
A
sses
s tr
eatm
ent p
roce
ss e
ffici
ency
and
imp
lem
ent
co
rrec
tive
actio
n to
opt
iimiz
eth
e tr
eatm
ent p
roce
ss;
C
omm
unic
ate
the
drin
kin
g w
ater
failu
re a
nd
aes
thet
ic
impa
ct t
o th
e re
leva
nt m
unic
ipal
sta
ff;
If
any
addi
tiona
l sam
ple
resu
lts e
xcee
d co
ncen
trat
ions
sp
ecifi
ed in
Ale
rt L
evel
II, p
roce
ed to
Ale
rt L
evel
III.
A
lert
Lev
el I
II (E
mer
genc
y)
G
eosm
in o
r 2-
MIB
>
20 n
g/L
Iron
>2
mg/
L
Man
gan
ese
>1
mg/
L
O
bjec
tiona
ble
and
incr
easi
ng
unp
leas
ant t
aste
s/od
our
s
Obj
ectio
nabl
e ta
ste
and
app
eara
nce,
sta
inin
g of
clo
the
s
Off-
putti
ng ta
ste
and
appe
aran
ce,
seve
re s
tain
ing
of c
loth
es a
nd
fixtu
res
Internal and External
Immediate
C
ontin
ue a
dditi
ona
l mon
itori
ng
and
ext
end
to th
e di
strib
utio
n sy
stem
and
po
int-
of-u
se to
est
ablis
h th
e so
urce
and
ext
ent
of th
e in
cid
ent
and
the
aest
hetic
impa
ct;
C
omm
unic
ate
aest
hetic
dri
nkin
g w
ater
em
erge
ncy
to
com
mun
ity;
Im
plem
ent
spe
cial
ist p
roce
ss a
sses
sme
nt a
nd
optim
isat
ion
of th
e dr
inki
ng w
ater
sup
ply
syst
em fr
om c
atch
men
t to
cons
umer
;
Pha
se o
ut a
dditi
ona
l mon
itori
ng
once
the
sou
rce
of th
e in
cid
ent h
as b
een
iden
tifie
d an
d re
ctifi
ed a
nd t
wo
cons
ecut
ive
resu
lts h
ave
bee
n w
ithin
spe
cific
atio
n;
P
repa
re n
otifi
catio
ns a
dvis
ing
of t
he e
nd o
f the
aes
thet
ic
drin
king
wat
er e
mer
gen
cy;
A
sses
s re
quire
d pr
eve
ntat
ive
actio
n to
red
uce
the
like
lihoo
d
of th
e in
cid
ent
recu
rrin
g;
P
repa
re a
rep
ort
to d
ocum
ent a
nd c
lose
the
inci
den
t;
Rev
iew
an
d up
date
Inci
den
t M
ana
gem
ent
Pro
toco
l;
Ret
rain
sta
ff on
rev
ised
Inci
dent
Man
agem
en
t Pro
toco
l.
20
Following any emergency, an investigation should be undertaken and all individuals involved in the WSP should be updated and a discussion of the performance of the WSP and issues or concerns must be addressed. The investigation should consider factors such as: What was the initiating cause of the problem? How was the problem first identified or recognised? What were the most essential actions required? What communication problems arose and how they were addressed? What were the immediate and long term consequences? How well did the emergency response plan work? 2.10 ESTABLISH DOCUMENTATION AND COMMUNICATION PROCEDURES If document updates are prepared as information becomes available, it reduces the amount of updating required at the end of the year and will allow Water Service Authorities to receive more up-to-date progress reports for their own planning services. Documentation of a WSP includes: Description and assessment of drinking water system including programmes to upgrade
existing water delivery. A plan for operational monitoring and verification of drinking water system. Water and safety management procedures for normal operation and incident/ emergency
situations (including communication plans). Description of supporting programmes. Communication strategies should include: Procedures for promptly advising of any significant incidents within the drinking water supply
including notification of the public health authority. Summary information to be available to consumers, e.g. through the media, annual reports
and on the internet Establishment of mechanisms to receive and actively address community complaints in a
timely fashion.
2.11 REVIEW OF THE WSP The results of the verification exercise should be used to evaluate and review the water safety plan to see whether the field assessments identified need modifications. This requires analysis of the verification data to see if there are any deficiencies in the WSP. If verification shows that microbial contamination is detected despite the presence of control measures within their critical limits, this immediately indicates that control measures have been identified incorrectly, the critical limits are inappropriate or the control measures are insufficient. Internal or third party (independent) verification is recommended for the development of institutional relationships. During the review, the following questions should be addressed: How well is the WSP working? Were the necessary management plans undertaken adequate? If not, which areas require improvement to provide long-term sustainability of the WSP? The WSP should be reviewed: Annually. After an incident. After any significant change to the water supply. In response to finding a weakness in the plan. Additional information regarding the system is received that might warrant a revised risk level
for that system.
21
SECTION 3: CHECKLIST FOR CONDUCTING A WSP
Yes No
1 Has a multi-disciplinary team of experts been assembled to carry out the water safety plan?
2 Has the team been informed of their duties and commitment?
3 Has the water treatment system been described?
(i.e. has each step in the system been considered for range and magnitude of hazards that may be present, and the ability of existing processes and infrastructure to manage actual or potential risks)
4 Following the description of the system above, has all the information been documented?
5 Has a flow diagram of the entire water supply system been constructed using the symbol chart?
6 Have existing, as well as potential., hazards in the system been identified?
7 Have these hazards been prioritised using the hazard assessment matrix provided?
8 Are there any control measures in place to reduce/eliminate the hazards?
9 Is there a system in place to monitor the control measures?
10 Have corrective actions been identified for each control measure, especially if the control measure fails?
11 Are there procedures in place to verify that the WSP is working effectively and will meet the health-based targets?
12 Have supporting programmes been developed to ensure that health based targets will be met?
13 Have management procedures been prepared to respond to “normal” and “incident” conditions?
14 Has all the relevant information regarding the water supply system been documented?
(i.e. description and assessment of the system, plan for operational monitoring, plan for verification of drinking water system, management procedures, etc.)
15 Have communication procedures been established?
(i.e. general information on water quality through the media, annual reports and on the internet, procedures for promptly advising of any significant incidents, mechanisms to receive and actively address community complaints, etc.)
16 Has the WSP been reviewed at the following stages?
Annually
After an incident
After any significant change to the water supply
In response to finding a weakness in the plan
Additional information regarding the system is received that might warrant a revised risk level for that system
22
SECTION 4: REFERENCES A Framework on How to Prepare and Develop Public Health Risk Management Plans for Drinking Water Supplies, Ministry of Health, Wellington, New Zealand, June 2005. Blueprint for Safe Drinking Water, Small Treatment Drinking Water Supplies, Introduction to Risk Management Planning, Ministry of Health, Wellington, New Zealand, June 2005. Canadian Guidance Document for Managing Drinking Water Systems: A Risk Assessment / Risk Management Approach, Prepared for Health Canada by: Canadian Water and Wastewater Association (CWWA), September, 2005. Chapman and Hall, Water Quality Assessments: A guide to the use of biota, sediments and water in environmental monitoring, First edition, 1992. Department of Water Affairs and Forestry: Drinking Water Quality Framework for South Africa, Edition 2, May 2007. Department of Water Affairs and Forestry, Department of Health, Water Research Commission; Quality of Domestic Water Supplies, Volume 1: Assessment Guide, Second Edition, 1998. Hendricks Lindiwe, Minister of Water Affairs and Forestry, Budget Vote Speech, May 2008 Howard G, Water safety plans for small systems: a model for applying HACCP concepts for cost-effective monitoring in developing countries, Water Science and Technology. 47(3):215-20, 2003. Improving the Efficiency of Disinfection in Small Drinking Water treatment Plants, K5/1531, Water Research Commission (SA), 2007. International Water Association (IWA), The Bonn Charter for safe drinking water, September 2004. NHMRC Rural and Remote Drinking Water Quality Management Modules, National Health and Medical Research Council Australia, Version 4, August 2005. Risk Assessment for Private Water Supplies, Section Four, Private Water Supplies (Government Organization), United Kingdom. Sam Godfrey, Guy Howard, Water safety plans for utilities in Developing countries, A case study from Kampala Uganda, Water, Engineering and Development Centre, Loughborough University, Leicestershire, United Kingdom, 2002. Sam Godfrey and Guy Howard, Water Safety Plans (WSP) for Urban Piped Water Supplies in Developing Countries, Water, Engineering and Development Centre, Loughborough University, Leicestershire, United Kingdom, 2004. Small Community Water Supply Management; WHO, Samorka, Orkuveita Reykjavikur; Reykjavik, Iceland, January 2005. Small Drinking Water Supplies – Preparing a Public Health Risk Management Plan, Ministry of Health, Wellington, New Zealand, June 2005. Techneau WP 4.2, Foundations for a framework for integrated risk assessment and methods for risk analysis Draft, March 2006. WHO1, Guidelines for drinking water quality, Chapter 2 – The guidelines: a framework for safe drinking water, 2004.
23
WHO2, Water Safety Plans – Managing drinking-water quality from catchment to consumer, World Health Organization, Geneva, 2005.
24
ANNEXURE A: RISK ASSESSMENT FORM
SECTION A: DESCRIPTION OF WATERWORKS
ITEM 1 Name of Waterworks
Ownership
Municipal DWAF Other Government
Private Farm Park Other (Specify)
Locality Urban Peri-urban Rural
Province Year of Construction Person in Charge of the Waterworks
Postal Address
Postal Code Telephone Fax E-mail (if any) GPS-Global Positioning System co-ordinates
ITEM 2
Diagram of the supply Provide a flow diagram showing the inter-relationships and various components of the supply source, treatment process and distribution system from the catchment to the consumer. The diagram should include: immediate catchment wider catchment collection point/s treatment processes used and major distribution pipe work (i.e. pumps, storage systems, pipelines)
Refer to the symbol chart and example of a flow diagram (Figures 4 and 5) before proceeding with a diagram of your own system. ITEM 3 In the sections that follow, an evaluation of the system is conducted in order to determine if any hazards exist or if any hazardous events are likely to occur. The hazard assessment matrix shown in Table 3 (page 10) is a guide to scoring the existing risks that could make water unsafe (i.e. cause a deterioration in water quality) and should be referred to throughout the evaluation.
Likelihood is determined by “how often’ or “how likely” a hazard or a hazardous event occurs. It should take into account hazards that have occurred in the past and their likelihood of re-occurrence and should also predict the likelihood of hazards and events that have not occurred to date.
25
Consequence looks at the severity of the results of the hazard/hazardous event and the seriousness or intensity of the impact of the hazard. When dealing with impact we are concerned with human health only.
RISK RATING = LIKELIHOOD CONSEQUENCE
Multiplying the derived likelihood ratings with derived consequence ratings from the risk assessment matrix produces a risk rating. e.g. a likelihood rating of 0.8 multiplied by a consequence rating of 70 would give a risk rating of 0.8 70 = 56, which would be ranked higher than an event with a likelihood of 0.2 and a consequence of 2 and a risk rating of 0.2 2 = 0.4. A higher score implies that a bigger risk of a hazardous event occurring exists and should therefore be prioritised. A risk profile is given below: Risk Profile: LOW – 0-10 MEDIUM – 11-56 HIGH – 57-100
SECTION B: EVALUATION OF CATCHMENT AND RAW WATER SOURCE
Name of Catchment
Name of Raw Water Supply Source
Location of the Source
(Mark with a cross where applicable)
What Source of Water Is Used?
Dam River/Stream Spring Borehole Wells Other (Specify)
Person in charge of the Supply
Postal Address
Postal code Telephone Fax E-mail GPS-Global Positioning System co-ordinates
(Mark with a cross where applicable)
26
Is The Water Source Vulnerable To Contamination From The Following?
Upstream industries
(list)
Agricultural/ livestock
farms
Sewer systems such as leaking septic tanks, etc.
Surface faecal run-off
Recreational use by the community
Other (Specify)
Indicate which of the source water protection plans exist?
Zoning Secure fencing
Locked gates
Limits on agriculture
(e.g. phosphorous,
pesticides)
Other (Specify)
Is The Quantity Of The Water Source Sufficient For The Community?
YES
NO
Has the quality of the source water deteriorated or otherwise changed in the last 5 years? If Yes, Explain
YES NO SPECIFY
Is the storage reservoir protected? YES NO SPECIFY CATCHMENT AND RAW WATER SOURCE EVALUATION
List existing risks that could make water unsafe (i.e. cause a deterioration in water quality)
Name the control
measure in place (if any)
Is the control
measure effective (Y/N)?
Likelihood of
occurrence
Consequence of occurrence
Risk Rating
Risk
Priority
L: Low M:
Medium H: High
e.g.
Livestock activity at
water source. Can cause illness from ingestion of
harmful micro-
organisms
Secure fencing
0.8 70 56 L M H
1 L M H 2 L M H 3 L M H
27
SECTION C: TREATMENT, DESIGN AND OPERATION RISK EVALUATION
ITEM 1
Classification of Waterworks
Average volume of water treated daily (ML/day)
Number of users who receive water from the waterworks (people)
Are there any flow meters installed at the waterworks?
Give a brief description of the waterworks in terms of any major events and upgrades that have occurred in the past
What infrastructure development plans exist for the short term?
What infrastructure development plans exist for the long term?
Primary purpose of treatment (Can be more than one)
Turbidity Removal
Colour Removal
DesalinationStabilization / Softening
Algae Removal
Nitrate Removal
Fluoride Removal
Iron and Manganese
Removal
Taste and Odour
Removal Disinfection Other (Specify)
Pre-treatment processes
Chlorination Ozonation Aeration Solids
Removal Other
(Specify)
Main treatment processes Coagulation Flocculation Sedimentation/Flotation Filtration
pH adjustment chemical (if any)
Lime Soda Ash CO2 Other
(Specify)
28
Disinfection (post treatment) Chlorine
Gas HTH Chloramination Other (Specify)
Does the plant comply with the requirements of the occupational safety, health and environmental act (OSH Act 1993)?
YES NO SPECIFY
Does the treated water meet the current standards (SANS 241) for drinking water quality?
YES NO SPECIFY
Are there leaks in the chemical mixing tanks?
YES NO SPECIFY
Is the chemical mixing tank maintained in a clean condition? (i.e. free from deposits/spillage/scum)
YES NO SPECIFY
Are there evident hydraulic surges at the raw water intake of the works?
YES NO SPECIFY
Is the sedimentation tank maintained in a clean condition? (i.e. free from deposits/algal growth/scum)
YES NO SPECIFY
Is the sand on the filter bed even? YES NO SPECIFY Is the filter backwashed according to its design guidelines?
YES NO SPECIFY
Are there mud balls or cracks in the filters?
YES NO SPECIFY
Are there evident cross connections between backwashed and treated waters?
YES NO SPECIFY
Is there evidence of insufficient coagulant dosing?
YES NO SPECIFY
Is the plant able to achieve the required residual chlorine levels?
YES NO SPECIFY
Has the works exceeded 75% of its volume capacity (ML/day)?
YES NO SPECIFY
Does the works have flexibility to meet demands for the next 5 years?
YES NO SPECIFY
Does the plant have a regular supply of treatment chemicals?
YES NO SPECIFY
Are the treatment chemicals stored in accordance with the material safety data sheets (MSDS)?
YES NO SPECIFY
Is the equipment regularly checked for reliability?
YES NO SPECIFY
Is there any back-up equipment for the following: Coagulant dosing pumps Disinfection dosing pumps
YESYES
NO NO
SPECIFY
Is there a back-up for power supply?
YES NO SPECIFY
Is there a routine inspection of maintenance on the plant and of equipment?
YES NO SPECIFY
29
Are there records of maintenance performed on the system?
YES NO SPECIFY
Are there any approved Operational and Maintenance Manuals for each unit process on the plant?
YES NO SPECIFY
Is the Operational and Maintenance Manual being actively used?
YES NO SPECIFY
Does the system have an approved emergency response plan? If yes, what is the frequency of use of the plan?
YES NO SPECIFY
Is the operator consistent in record keeping and providing the appropriate reports throughout the year?
YES NO SPECIFY
Frequency of operational monitoring N: Not done H: More than once daily D: Once Daily W: Once Weekly M: Monthly 2: Every 2 months 3: Every 3 months A: Annually
Turbidity Residual Chlorine
pH Jar Tests
Frequency of compliance monitoring N: Not done H: More than once daily D: Once Daily W: Once Weekly M: Monthly 2: Every 2 months 3: Every 3 months A: Annually
Turbidity Residual Chlorine
pH Metals
Hardness Colour Microbiologi
cal Other
(Specify)
pH Turbidity Chlorine Conductiv
ity
Iron and Mangane
se Jar Tests
Is there proper equipment available to conduct operational monitoring of the following?
YES YES YES YES YES YES
NO NO NO NO NO NO
Is the equipment calibrated?
YES YES YES YES YES YES
NO NO NO NO NO NO
30
Residuals management: Methods of treatment
Coagulant Recovery
Recycling of
Residuals Streams
Discharge to Sewer
Settling Thickening Other
(Specify)
Residuals management: Methods of disposal
Drying bed Sludge dam Land
application Sewer
Other (Specify)
ITEM 2
Number of actual operators Full-time Day time Part-time
Number of operators required Full-time Day time Part-time
What level of training does the operator/s have?
NQF2 NQF4 NQF5 Other (Specify)
NQF2 – Grade 10 NQF4 – Grade 12 NQF5 – Grade 12 + 2
Is the operator currently undergoing training?
YES NO SPECIFY
List the operators’ training needs in order of priority
What level of training does the supervisor have?
NQF2 NQF4 NQF5 Other (Specify)
NQF2 – Grade 10 NQF4 – Grade 12 NQF5 – Grade 12 + 2
Is the supervisor currently undergoing training?
YES NO SPECIFY
List the supervisor’s training needs in order of priority
TREATMENT, DESIGN AND OPERATION RISK EVALUATION
List existing risks that could make water unsafe (i.e. cause a deterioration in water quality)
Name the control
measure in place (if any)
Is the control
measure effective (Y/N)?
Likelihood of
occurrence
Conse-quence of
occurrence
Risk Rating
Risk
Priority
L: Low M: Medium
H: High
e.g.
Optimal pH
prior to coagulation
not achieved. Floc
formation not optimal.
None
1 70 70 L M H
1 L M H 2 L M H 3 L M H
31
SECTION D: DISTRIBUTION RISK EVALUATION ITEM 1 – Primary mains
Is there evidence of the following in the vicinity of the pipe?
Leakage Human/Animal
faeces Solid waste
Excessive algal growth
YES NO YES NO YES NO YES NO
Does the primary main pass through stagnant water?
YES NO SPECIFY
ITEM 2 – On-site Service reservoir/s
Are the vents covered? YES NO SPECIFY Are the inspection covers or concrete around cover damaged or corroded?
YES NO SPECIFY
Is there any observable part of the inside of the tank corroded or damaged (including: ladders, roof struts, walls)?
YES NO SPECIFY
Is there evidence of leakage/cracks on the walls?
YES NO SPECIFY
Can run-off form stagnant pools close to the reservoir?
YES NO SPECIFY
Can stagnant or dirty water collect in valve boxes or washout chambers?
YES NO SPECIFY
Is the reservoir fenced and secure?
YES NO SPECIFY
Is there evidence of human/animal faecal material around the valve box/chamber, reservoir vents and/or inspection covers?
YES NO SPECIFY
Is the reservoir cleaned? If so, how often?
YES NO SPECIFY
Are there any valve leaks? YES NO SPECIFY ITEM 3 – Off-site Service reservoir/s
Are the vents covered? YES NO SPECIFY Are the inspection covers or concrete around cover damaged or corroded?
YES NO SPECIFY
Is there any observable part of the inside of the tank corroded or damaged (including: ladders, roof struts, walls)?
YES NO SPECIFY
Is there evidence of leakage/cracks on the walls?
YES NO SPECIFY
Can run-off form stagnant pools close to the reservoir?
YES NO SPECIFY
Can stagnant or dirty water collect in valve boxes or washout chambers?
YES NO SPECIFY
Is the reservoir fenced and secure?
YES NO SPECIFY
32
Is there evidence of human/animal faecal material around the valve box/chamber, reservoir vents and/or inspection covers?
YES NO SPECIFY
Is the reservoir cleaned? If so, how often?
YES NO SPECIFY
Are there any valve leaks? YES NO SPECIFY ITEM 4 – Booster Stations
Is disinfectant added to the water at the booster station?
YES NO SPECIFY
Is any observable part of the booster station corroded or damaged (including: ladders, roof struts and walls)?
YES NO SPECIFY
Is there evidence of leakage/cracks, etc. in the booster?
YES NO SPECIFY
Can run-off form stagnant pools close to the booster?
YES NO SPECIFY
Can stagnant or dirty water collect in valve boxes?
YES NO SPECIFY
Is the booster station fenced and secure?
YES NO SPECIFY
Is there evidence of faecal material around the valve box/chamber?
YES NO SPECIFY
Is the booster station cleaned? If so, how often
YES NO SPECIFY
Are there any valve leaks? YES NO SPECIFY Is the connecting main leaking? YES NO SPECIFY Are backflow preventers installed in the supply main?
YES NO SPECIFY
ITEM 5 – Valve Boxes/Chambers (Other than those covered as part of service reservoirs and booster stations
Are the valves operational? YES NO SPECIFY Is the valve box cover cracked? YES NO SPECIFY Is the valve corroded? YES NO SPECIFY Does the valve leak? YES NO SPECIFY Is there debris or faecal matter in the valve box/chamber?
YES NO SPECIFY
Is the valve box designed without a washout?
YES NO SPECIFY
Is there stagnant water in the valve box?
YES NO SPECIFY
ITEM 6 – Pipes in the Vicinity of Roads, Drains and Ditches
Are there evident standpipes connected to the valves?
YES NO SPECIFY
Is there a valve box within 1 meter of a road crossing?
YES NO SPECIFY
Is the supply pipe close to the road crossing?
YES NO SPECIFY
Is there evidence of faecal matter in the area surrounding the pipe?
YES NO SPECIFY
33
Is there evidence of leaks around the pipe?
YES NO SPECIFY
Does the pipe cross an open trench/ditch?
YES NO SPECIFY
Is there waste material around the pipe?
YES NO SPECIFY
Is the pipe submerged in stagnant water?
YES NO SPECIFY
Is the pipe visibly damaged/cracked/leaking?
YES NO SPECIFY
ITEM 7 – Standpipes/House Connections
Do any standpipes leak? YES NO SPECIFY Does surface water collect around any standpipe?
YES NO SPECIFY
Are the supply pipes in the vicinity of the stand pipes exposed?
YES NO SPECIFY
Is there any faecal matter on the ground within 10m of any standpipe?
YES NO SPECIFY
Is the main supply pipe submerged in stagnant water?
YES NO SPECIFY
Are there solid waste dumps within 10m from the standpipes?
YES NO SPECIFY
Does the main supply pipe pass through sewage/pit latrines/septic tank/ foul water bodies?
YES NO SPECIFY
Does the main pipe cross a drain/ditch?
YES NO SPECIFY
DISTRIBUTION RISK EVALUATION
List existing risks that could make water unsafe (i.e. cause a deterioration in water quality)
Name the control
measure in place (if any)
Is the control
measure effective (Y/N)?
Likelihood of
occurrence
Consequence of occurrence
Risk Rating
Risk
Priority
L: Low M:
Medium H: High
e.g.
Water
contaminated due to
backflow
Positive pressure
maintained in the
distribution system
0.5 70 35 L M H
1 L M H2 L M H3 L M H
34
AN
NE
XU
RE
B:
CO
RR
EC
TIV
E A
CT
ION
S
H
azar
d
Ris
kC
orr
ect
ive
acti
on
/sS
UR
FA
CE
WA
TE
RS
(R
IVE
RS
an
d S
TR
EA
MS
) Li
vest
ock,
hum
an a
ctiv
ity a
t w
ater
sou
rce.
Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
Hea
lth a
nd
aest
hetic
impa
cts.
A
cces
s pr
eve
ntio
n.
Lim
its o
n a
gric
ultu
re.
Con
tour
ba
nks
to r
educ
e er
osio
n.
Ra
w w
ater
turb
id a
fter
heav
y ra
in. M
ay
cont
ain
dr
oppi
ngs
of a
nim
als
and
bird
s.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
D
isin
fect
ion
affe
cted
. In
crea
sed
org
ani
c m
atte
r le
ad
s to
pro
duct
ion
of
disi
nfec
tion
by-
prod
ucts
.
Use
alte
rnat
e so
urce
s of
wat
er,
sw
itch
supp
ly u
ntil
turb
idity
and
was
te m
ater
ial s
ettle
s.
Mon
itor
rain
fall
patte
rns
in c
atch
men
t to
deve
lop:
Str
ateg
ies
to m
ana
ge r
ainf
all
U
nder
stan
din
g of
impa
ct o
f rai
nfal
l on
wat
er q
ualit
y D
ead
anim
als
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
T
aste
and
odo
ur p
rob
lem
s.
Reg
ular
pat
rols
to
rem
ove
dea
d an
imal
s.
Dro
ppi
ngs
of a
nim
als/
bird
s ca
n in
trod
uce
har
mfu
l mic
ro-
orga
nism
s in
to t
he w
ater
bo
dy
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms
Con
side
r co
ntro
l of l
arg
e po
pul
atio
ns o
f an
imal
s (e
.g.
zoni
ng).
Lo
w fl
ow
, hig
h nu
trie
nt le
vels
and
wa
rm c
ondi
tions
– c
an
mak
e cy
anob
act
eria
l and
alg
al g
row
th m
ore
likel
y.
Tas
te a
nd o
dour
pro
ble
ms
caus
ed b
y cy
ano
bact
eria
. S
ome
spec
ies
of c
yano
bac
teri
a pr
oduc
e to
xins
. D
raw
hig
hes
t qua
lity
wat
er a
nd
have
var
iabl
e d
epth
off-
take
s to
avo
id a
lgal
gro
wth
. A
pply
alg
aec
ides
if r
equi
red.
F
allin
g w
ater
leve
ls d
ue
to d
roug
ht o
r dr
aw
do
wn
of w
ater
bo
dy.
T
urbi
dity
from
ero
sion
, pre
senc
e of
iron
and
man
gane
se,
incr
eas
ed o
rga
nic
mat
ter
(pro
duct
ion
of D
BP
s), a
esth
etic
qu
alit
y of
wat
er a
ffect
ed b
y pr
esen
ce o
f alg
ae,
Fe
and
Mn
and
som
e al
gae
pro
duce
toxi
ns.
Use
alte
rnat
e so
urce
of
wat
er if
ava
ilabl
e, d
eve
lop
wat
er
rest
rictio
n st
rate
gy
and
impl
em
ent
wh
en
wat
er le
vels
fall.
Van
dal
ism
or
sabo
tage
ma
y p
ollu
te th
e w
ater
with
ch
emic
als
or m
icro
bes
or
dam
age
equ
ipm
ent
and
in
fras
truc
ture
.
Hea
lth a
nd
aest
hetic
impa
cts
from
the
pres
en
ce o
f ch
emic
als.
Ill
ness
from
pre
senc
e of
mic
ro-o
rgan
ism
s.
Inte
rrup
tion
to s
upp
ly.
Lim
it ac
cess
in th
e vi
cini
ty o
f wat
er in
take
s.
Mak
e su
re c
atch
men
t is
prot
ect
ed (
e.g.
reg
ula
r pa
trol
s).
Inta
ke s
cree
ns b
ecom
e cl
ogge
d or
dam
age
d.
Sup
ply
ma
y be
red
uce
d.
Che
ck s
cre
ens
regu
larl
y an
d re
mov
e m
ater
ial.
Bus
hfire
s ca
n re
sult
in fi
re r
etar
dant
s in
the
wat
er
sour
ce.
Loss
of v
eget
atio
n ca
n re
sult
in th
e pr
ese
nce
of t
urbi
dity
an
d or
gani
c m
atte
r.
Hea
lth r
isk
and
aes
thet
ic r
isk
from
pre
senc
e of
ch
emic
als.
A
n in
cre
ase
d tu
rbid
ity a
nd v
ege
tatio
n in
terf
ere
s w
ith
disi
nfec
tion
resu
ltin
g in
illn
ess
from
pre
senc
e of
mic
ro-
orga
nism
s.
Mor
e D
BP
s al
so p
rod
uce
d.
Dev
elop
and
impl
eme
nt h
azar
d re
duc
tion
stra
tegi
es.
Mai
nta
in fi
re a
cces
s ro
ads.
M
aint
ain
cont
act
with
loca
l fir
e se
rvic
es.
Iden
tify
appr
opria
te fi
re r
etar
dan
ts.
35
H
azar
d
Ris
kC
orr
ect
ive
acti
on
/sB
OR
EH
OL
ES
Live
stoc
k, h
uman
act
ivity
at
wat
er s
ourc
e. S
hal
low
bo
reho
les
in h
ighl
y p
erm
eabl
e so
ils o
r fr
actu
red
rock
aq
uife
rs a
re m
ore
vuln
era
ble
to c
onta
min
atio
n.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
an
d ae
sthe
tic im
pact
s fr
om c
hem
ical
s.
Ens
ure
prot
ectiv
e m
easu
res
are
mai
nta
ine
d, e
.g.
min
imum
pro
tect
ion
zon
e (e
.g. 5
0m)
arou
nd
bore
hole
. (L
arg
e bu
ffer
zone
s m
ay
be
requ
ired
for
sha
llow
bor
eho
le
or fo
r pe
rmea
ble
soils
or
frac
ture
d ro
ck a
qui
fers
).
Acc
ess
prev
en
tion.
Li
mits
on
agr
icul
ture
. C
onto
ur b
ank
s to
red
uce
eros
ion.
G
roun
dw
ate
r m
ay
cont
ain
heal
th r
elat
ed c
hem
ical
s (e
.g.
arse
nic
, bar
ium
, flu
orid
e, u
rani
um, r
adiu
m)
as a
res
ult o
f lo
cal g
eolo
gy.
Hea
lth r
isk
or a
esth
etic
imp
act o
f che
mic
als.
T
est g
roun
dw
ate
r fo
r he
alth
re
late
d ch
emic
als
bef
ore
com
mis
sio
ning
the
bore
hol
e fo
r a
drin
king
wat
er s
upp
ly
Sur
face
wat
er e
nter
ing
a b
ore
hole
can
incr
ease
the
turb
idity
and
/or
ma
y co
ntai
n th
e dr
oppi
ngs
of a
nim
als
or
bird
s w
hic
h co
ntai
n h
arm
ful m
icro
-org
anis
ms.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
D
isin
fect
ion
affe
cted
. In
crea
sed
org
ani
c m
atte
r le
ad
s to
pro
duct
ion
of D
BP
s.
Con
stru
ct b
ore
hole
to p
reve
nt th
e en
try
of s
urf
ace
wa
ter.
E
nsur
e st
ruct
ures
rem
ain
inta
ct a
nd th
at r
epa
irs
are
initi
ated
wh
en f
aults
are
re
port
ed (
e.g.
cra
ckin
g).
Sea
l pum
ps a
nd
wa
ter
outle
ts to
pre
vent
the
entr
y of
su
rfac
e w
ater
. S
urro
und
the
bor
ehol
e w
ith a
con
cret
e sl
ab/p
linth
at l
eas
t 2m
in d
iam
eter
slo
ping
aw
ay
from
the
bore
hole
he
ad.
Enc
ase
the
bore
hole
in a
wat
ert
ight
con
cret
e se
al.,
e.g.
at
leas
t 3m
in d
epth
to p
reve
nt th
e en
try
of s
urfa
ce w
ate
r.
The
sea
l sho
uld
ext
end
at le
ast
30c
m a
bove
the
gro
und
to
pre
vent
the
entr
y of
sur
face
wa
ter.
Mak
e su
re th
at th
e ai
r ve
nts/
air
lines
face
do
wn
war
ds, a
re s
cree
ned
and
are
ab
ove
the
leve
l of a
1 in
100
yea
r flo
od.
C
ap a
nd s
eal
mon
itorin
g b
oreh
ole
in th
e vi
cini
ty.
Van
dal
ism
or
sabo
tage
ma
y p
ollu
te th
e w
ater
with
ch
emic
als
or m
icro
bes
or
dam
age
equ
ipm
ent
and
in
fras
truc
ture
.
Hea
lth a
nd
aest
hetic
impa
cts
from
the
pres
en
ce o
f ch
emic
als.
Ill
ness
from
pre
senc
e of
mic
ro-o
rgan
ism
s.
Inte
rrup
tion
to s
upp
ly.
Pro
tect
the
bore
hole
hea
d a
nd
pum
ps.
Reg
ular
pat
rols
of a
rea.
Wat
er m
ay
con
tain
nat
ural
ly o
ccur
ring
iron
and
m
ang
anes
e
Aes
thet
ic im
pa
cts
on c
olou
r a
nd ta
ste
(pot
en
tial f
or
stai
ning
).
Opt
iimiz
ew
ate
r tr
eatm
ent p
roce
sses
to r
emov
e iro
n a
nd
man
gan
ese.
36
H
azar
d
Ris
kC
orr
ect
ive
acti
on
/sS
PR
ING
S
Spr
ing
mus
t be
des
igne
d to
pro
tect
spr
ing
fro
m
lives
tock
, hum
an a
ctiv
ity a
t w
ater
sou
rce.
S
hallo
w b
ore
hol
es in
hig
hly
per
mea
ble
soils
or
frac
ture
d ro
ck a
quife
rs a
re m
ore
vuln
erab
le to
con
tam
inat
ion.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
an
d ae
sthe
tic im
pact
s fr
om c
hem
ical
s.
Ens
ure
prot
ectiv
e m
easu
res
are
mai
nta
ine
d, e
.g.
min
imum
pro
tect
ion
zon
e (e
.g. 5
0m)
arou
nd
bore
hole
. (L
arg
e bu
ffer
zone
s m
ay
be
requ
ired
for
sha
llow
bo
reho
le o
r fo
r pe
rme
able
soi
ls o
r fr
actu
red
rock
aq
uife
rs).
A
cces
s pr
eve
ntio
n.
Lim
its o
n a
gric
ultu
re.
App
ropr
iate
sp
ring
enc
asem
ent
. G
roun
dw
ate
r/sp
ring
wat
er m
ay
cont
ain
hea
lth r
elat
ed
chem
ical
s (e
.g.
arse
nic,
bar
ium
, flu
orid
e, u
rani
um,
radi
um)
as a
re
sult
of lo
cal g
eol
og
y.
Hea
lth r
isk
or a
esth
etic
imp
act o
f che
mic
als
Tes
t gro
und
wa
ter
for
heal
th r
ela
ted
chem
ica
ls b
efor
e co
mm
issi
oni
ng th
e bo
reh
ole
for
a dr
inki
ng w
ater
sup
ply
.
Van
dal
ism
or
sabo
tage
ma
y p
ollu
te th
e w
ater
with
ch
emic
als
or m
icro
bes
or
dam
age
equ
ipm
ent
and
in
fras
truc
ture
.
Hea
lth a
nd
aest
hetic
impa
cts
from
the
pres
en
ce o
f ch
emic
als.
Ill
ness
from
pre
senc
e of
mic
ro-o
rgan
ism
s.
Inte
rrup
tion
to s
upp
ly.
Pro
tect
the
spri
ng a
nd
pum
ps.
Mak
e su
re c
atch
men
t is
prot
ect
ed (
secu
re fe
ncin
g,
lock
ed
gate
s, r
egu
lar
patr
ols)
.
Wat
er m
ay
con
tain
nat
ural
ly o
ccur
ring
iron
and
m
ang
anes
e.
Aes
thet
ic im
pa
cts
on c
olou
r a
nd ta
ste
(pot
en
tial f
or
stai
ning
).
Opt
iimiz
ew
ate
r tr
eatm
ent p
roce
sses
to r
emov
e iro
n a
nd
man
gan
ese
S
urfa
ce w
ater
ent
erin
g th
e b
ore
hole
can
incr
ease
the
turb
idity
and
/or
ma
y co
ntai
n th
e dr
oppi
ngs
of a
nim
als
or
bird
s w
hic
h co
ntai
n h
arm
ful m
icro
-org
anis
ms.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
D
isin
fect
ion
affe
cted
. In
crea
sed
org
ani
c m
atte
r le
ad
s to
pro
duct
ion
of D
BP
s.
Con
stru
ct s
prin
g en
case
me
nt to
pre
vent
the
entr
y of
su
rfac
e w
ater
.
Ens
ure
stru
ctur
es r
emai
n in
tact
and
that
rep
air
s ar
e in
itiat
ed w
hen
fau
lts a
re r
epo
rted
(e.
g. c
rack
ing)
. E
stab
lish
a m
inim
um p
rote
ctio
n zo
ne (
e.g.
50
m)
arou
nd
each
spr
ing.
M
ake
sure
eac
h sp
ring
has
a su
rfac
e dr
ain
age
ditc
h lo
cate
d up
hill
from
the
sour
ce t
o in
terc
ept a
nd
dive
rt
surf
ace
wat
er r
un-o
ff.
Mak
e su
re s
prin
g ha
s a
n im
per
mea
ble
laye
r of
con
cret
e be
hin
d th
e sp
ring
box
or e
nca
sem
ent a
nd
abov
e th
e e
ye
of th
e sp
ring.
37
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
IMP
OU
ND
ME
NT
S (
DA
MS
) U
rba
n ar
eas
and
was
tew
ate
r di
sch
arge
(p
erm
itted
or
una
utho
rised
) ca
n le
ad to
po
llutio
n of
wat
er w
ith h
arm
ful
orga
nism
s. E
xten
t of p
ollu
tion
will
be
depe
nden
t on
leve
l of
trea
tmen
t an
d m
ana
gem
ent
of s
ew
age
col
lect
ion
syst
em, a
nd
ext
ent o
f dilu
tion
in th
e ca
tchm
ent
sto
rage
.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
If
ther
e is
a lo
calis
ed
trea
tme
nt o
f w
aste
wa
ter,
then
m
inim
ized
isch
arge
into
the
wat
er b
ody.
If w
aste
wat
er is
di
sch
arge
d, m
ake
sure
that
the
leve
l of t
rea
tmen
t is
high
to
red
uce
the
impa
cts
of h
arm
ful m
icro
-org
anis
ms
on
the
rece
ivin
g w
ater
bod
y.
Whe
reve
r p
ossi
ble,
use
land
bas
ed r
ecyc
ling.
Mak
e su
re
sew
age
col
lect
ion
syst
ems
are
pro
perl
y en
gin
eere
d an
d w
ell
ma
inta
ine
d an
d th
at s
pills
and
ove
rflo
ws
are
man
age
d du
rin
g st
orm
eve
nts.
D
evel
op e
mer
gen
cy a
nd
inci
den
t pla
ns to
de
al w
ith
wa
ste
wat
er s
pills
. M
ake
sure
that
the
dom
estic
wa
ste
wat
er s
yste
ms
are
not n
ear
the
wat
er b
odie
s (e
.g. a
t lea
st 5
0 m
aw
ay
from
so
urce
).
Urb
an
area
s ca
n po
llute
wat
er
via
una
utho
rised
di
sch
arge
of c
hem
ical
s or
spi
lls fr
om s
tore
d ch
emic
als.
H
ealth
or
aest
het
ic im
pact
cau
sed
by
chem
ical
s.
Con
duct
com
mun
ity e
duc
atio
n p
rogr
amm
es.
Rec
reat
ion
al a
ctiv
ities
can
ca
use:
mic
rob
ial (
faec
al
wa
ste)
an
d ch
em
ical
(bo
atin
g) c
onta
min
atio
n an
d so
il er
osio
n (o
ff ro
ad
vehi
cles
).
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
an
d ae
sthe
tic im
pact
s.
Incr
ease
d tu
rbid
ity c
an in
terf
ere
with
dis
infe
ctio
n.
Incr
ease
d or
ga
nic
mat
ter
will
giv
e ris
e to
an
incr
ease
in
DB
Ps.
Ens
ure
toile
ts w
ith s
ew
er
ma
nag
emen
t and
rub
bis
h bi
ns
are
ava
ilabl
e.
Con
duct
pu
blic
edu
catio
n pr
ogr
amm
es.
Res
tric
t act
iviti
es w
her
e re
quir
ed.
Was
tew
ater
dis
char
ge
can
lead
to a
n in
crea
se in
nu
trie
nt le
vels
in c
atch
men
ts a
nd r
eser
voirs
. In
crea
sed
nutr
ient
s ca
n le
ad t
o th
e fo
rmat
ion
of a
lgae
. M
ake
sure
wa
ste
wa
ter
stor
ages
are
pro
perly
co
nstr
ucte
d a
nd
lined
so
that
the
y do
not
leak
. D
evel
op e
mer
gen
cy a
nd
inci
den
t res
pons
e p
lans
to d
eal
w
ith w
aste
wa
ter
spill
s.
Urb
an
area
s ca
n be
a s
ourc
e fo
r tu
rbid
ity,
litte
r an
d p
lant
de
bris
in th
e w
ater
bod
y.
Ph
ysic
al q
ualit
y of
wat
er p
oor.
In
crea
sed
turb
idity
and
org
ani
c m
atte
r ca
n in
terf
ere
with
di
sinf
ectio
n an
d le
ad
to th
e fo
rmat
ion
of D
BP
s.
Con
duct
com
mun
ity e
duc
atio
n p
rogr
amm
es a
bout
the
nee
d to
min
imiz
epo
llutio
n of
wat
er b
odi
es b
y lit
ter,
de
bris
and
pla
nt m
ater
ials
A
cces
s to
res
erv
oirs
can
lead
to
acci
dent
al d
amag
e to
in
fras
truc
ture
and
incr
ease
d co
ntam
inat
ion
from
spi
lls
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als.
Li
mit
acce
ss.
Agr
icul
tura
l act
iviti
es in
volv
ing
live
stoc
k ca
n po
llute
the
wat
er w
ith h
arm
ful o
rga
nism
s. T
he c
once
ntra
tion
of
pollu
tant
is d
epen
den
t on
inte
nsity
of a
ctiv
ity a
nd le
vel o
f ac
cess
to s
tora
ge a
rea.
Illne
ss fr
om in
ges
tion
of h
arm
ful o
rgan
ism
s.
Pre
vent
live
sto
ck a
cces
s b
y fe
ncin
g.
Red
uce
imp
acts
of s
urfa
ce r
un-o
ff ca
rryi
ng f
aeca
l was
te
thro
ugh
the
use
of r
ipar
ian
zone
s.
Min
imiz
eint
ensi
ve li
vest
ock
activ
ity n
ear
imp
oun
dmen
ts.
Agr
icul
tura
l pra
ctic
es m
ay
lea
d to
con
tam
ina
tion
by
toxi
c ch
emic
als
incl
udi
ng
pest
icid
es, s
pilla
ge o
f die
sel a
nd
petr
oleu
m p
rod
ucts
.
Hea
lth o
r ae
sth
etic
impa
cts
of c
hem
ical
s.
Intr
oduc
e co
des
of p
ract
ice
to fa
rmer
s to
impr
ove
man
age
me
nt a
nd m
inim
izet
he
ent
ry o
f pes
ticid
es in
to
the
wat
er b
ody.
M
inim
izet
he u
se/s
tora
ge o
f die
sel w
ithin
the
catc
hmen
t. P
rote
ct w
ith b
und
ing
and
ph
ysic
al b
arrie
rs to
con
tain
sp
ills.
38
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
Agr
icul
tura
l pra
ctic
es m
ay
incr
ease
nut
rient
leve
ls in
w
ater
du
e to
the
entr
y of
fert
ilise
rs o
r ni
trog
eno
us
com
poun
ds a
ssoc
iate
d w
ith li
vest
ock.
Incr
ease
d nu
trie
nts
can
lead
to
the
gro
wth
of a
lga
e.
Cer
tain
spe
cie
s of
alg
ae c
onta
in to
xins
an
d ca
n ha
ve
serio
us h
ealth
effe
cts.
C
erta
in s
peci
es
of a
lgae
pro
duc
e ta
ste
and
odo
ur
prob
lem
s.
Intr
oduc
e co
des
of p
ract
ice
to im
prov
e m
ana
gem
ent
by
farm
ers
and
min
imiz
ethe
ent
ry o
f nut
rient
s fr
om
agric
ultu
ral a
ctiv
ities
in w
ater
bod
ies.
For
estr
y in
volv
ing
the
dev
elop
men
t of t
imbe
r pl
ant
atio
ns
can
lead
to th
e d
isch
arge
of p
estic
ides
an
d h
erbi
cide
s.
Hea
lth im
pact
of c
hem
ica
ls.
Dev
elop
cod
es o
f pra
ctic
e to
ens
ure
the
use
of
pest
icid
es o
r h
erbi
cide
s is
un
dert
ake
n in
a m
ann
er th
at
that
min
imis
es im
pact
s on
wat
er b
odie
s.
Dev
elop
inci
de
nt e
mer
genc
y pl
ans
. A
gric
ultu
ral p
ract
ices
and
live
stoc
k ca
n ca
use
ero
sio
n ar
ound
the
wat
er b
ody
and
lead
to a
n in
crea
se in
tu
rbid
ity.
Incr
ease
d tu
rbid
ity c
an in
terf
ere
with
dis
infe
ctio
n an
d le
ad
to th
e fo
rmat
ion
of D
BP
s (in
crea
ses
the
risk
of
mic
ro-o
rgan
ism
s to
be
pres
ent
in th
e w
ater
).
Intr
oduc
e co
des
of p
ract
ice
to m
inim
izee
rosi
on
and
poss
ible
impa
cts
on w
ater
qu
ality
with
in b
odi
es.
For
estr
y ca
n ca
use
eros
ion
on th
e w
ater
bod
y an
d le
ad
to a
n in
crea
se in
turb
idity
. In
crea
sed
turb
idity
can
inte
rfe
re w
ith d
isin
fect
ion
and
lea
d to
the
form
atio
n of
DB
Ps
(incr
ease
s th
e ris
k of
m
icro
-org
anis
ms
to b
e pr
ese
nt in
the
wat
er).
Intr
oduc
e co
des
of p
ract
ice
to m
inim
izee
rosi
on
and
poss
ible
impa
cts
on w
ater
qu
ality
with
in b
odi
es
Mak
e su
re th
at d
isus
ed
are
as a
re r
ehab
ilita
ted.
A
fter
heav
y ra
in,
wat
er e
nter
ing
imp
oun
dme
nt m
ay
be
turb
id a
nd c
ont
ain
drop
pin
gs o
f ani
ma
ls/b
irds
and
cont
ain
high
leve
ls o
f org
ani
c m
atte
r.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
D
isin
fect
ion
affe
cted
. In
crea
sed
org
ani
c m
atte
r le
ad
s to
pro
duct
ion
of D
BP
s.
Use
alte
rnat
e so
urce
s of
wat
er,
sw
itch
supp
ly u
ntil
turb
idity
and
was
te m
ater
ial s
ettle
s.
Mon
itor
rain
fall
patte
rns
in c
atch
men
t to
deve
lop:
Str
ateg
ies
to m
ana
ge r
ainf
all
U
nder
stan
din
g of
impa
ct o
f rai
nfal
l on
wat
er q
ualit
y D
ead
anim
als.
Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
Tas
te a
nd o
dour
pro
ble
ms.
Reg
ular
pat
rols
to
rem
ove
dea
d an
imal
s.
Low
flo
w, h
igh
nutr
ient
leve
ls a
nd w
arm
con
ditio
ns –
can
m
ake
cyan
oba
cter
ial a
nd a
lga
l gro
wth
mor
e lik
ely.
T
aste
and
odo
ur p
rob
lem
s ca
used
by
cya
noba
cter
ia.
Som
e sp
ecie
s of
cya
nob
acte
ria
prod
uce
toxi
ns.
Dra
w h
igh
est q
ualit
y w
ater
an
d ha
ve v
aria
ble
dep
th o
ff-ta
kes
to a
void
alg
al g
row
th.
App
ly a
lga
ecid
es if
req
uire
d.
Wat
er s
trat
ifica
tion
can
lea
d to
low
oxy
gen
co
nce
ntra
tions
at l
ow
er le
vels
.
Pro
mot
es a
lgal
gro
wth
an
d re
leas
es F
e an
d M
n fr
om
sedi
men
ts.
Tas
te a
nd o
dour
pro
ble
ms
caus
ed b
y cy
ano
bact
eria
an
d F
e an
d M
n. R
ed/
bro
wn
susp
ens
ions
in w
ater
cau
se
stai
ning
. S
ome
spec
ies
of c
yano
bac
teri
a pr
oduc
e to
xins
.
Dra
w h
igh
est q
ualit
y w
ater
an
d ha
ve v
aria
ble
dep
th o
ff-ta
kes
to a
void
alg
al g
row
th.
Fal
ling
wat
er le
vels
du
e to
dro
ught
or
dra
wd
ow
n of
wat
er
bod
y.
Tur
bidi
ty fr
om e
rosi
on, p
rese
nce
of ir
on a
nd m
anga
nese
, in
cre
ased
org
ani
c m
atte
r (p
rodu
ctio
n of
DB
Ps)
, aes
thet
ic
qua
lity
of w
ater
affe
cted
by
pres
ence
of a
lga
e, F
e an
d M
n an
d so
me
alg
ae p
rodu
ce to
xins
.
Use
alte
rnat
e so
urce
of
wat
er if
ava
ilabl
e, d
eve
lop
wat
er
rest
rictio
n st
rate
gy
and
impl
em
ent
wh
en
wat
er le
vels
fall.
Bus
hfire
s ca
n re
sult
in fi
re r
etar
dant
s in
the
wat
er
sour
ce.
Loss
of v
eget
atio
n ca
n re
sult
in th
e pr
ese
nce
of t
urbi
dity
an
d or
gani
c m
atte
r.
Hea
lth r
isk
and
aes
thet
ic r
isk
from
pre
senc
e of
ch
emic
als.
A
n in
cre
ase
d tu
rbid
ity a
nd v
ege
tatio
n in
terf
ere
s w
ith
disi
nfec
tion
resu
ltin
g in
illn
ess
from
pre
senc
e of
mic
ro-
orga
nism
s.
Mor
e D
BP
s al
so p
rod
uce
d.
Dev
elop
and
impl
eme
nt h
azar
d re
duc
tion
stra
tegi
es.
Mai
nta
in fi
re a
cces
s ro
ads.
M
aint
ain
cont
act
with
loca
l fir
e se
rvic
es.
Iden
tify
appr
opria
te fi
re r
etar
dan
ts.
39
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
Van
dal
ism
or
sabo
tage
ma
y p
ollu
te th
e w
ater
with
ch
emic
als
or m
icro
bes
or
dam
age
equ
ipm
ent
and
in
fras
truc
ture
.
Hea
lth a
nd
aest
hetic
impa
cts
from
the
pres
en
ce o
f ch
emic
als.
Ill
ness
from
pre
senc
e of
mic
ro-o
rgan
ism
s.
Inte
rrup
tion
to s
upp
ly.
Lim
it ac
cess
in th
e vi
cini
ty o
f wat
er in
take
s.
Mak
e su
re c
atch
men
t is
prot
ect
ed (
secu
re fe
ncin
g,
lock
ed
gate
s, r
egu
lar
patr
ols)
.
Inta
ke s
cree
ns b
ecom
e cl
ogge
d or
dam
age
d.
Sup
ply
ma
y be
red
uce
d.
Che
ck s
cre
ens
regu
larl
y an
d re
mov
e m
ater
ial.
PR
E-O
XID
AT
ION
Und
er d
osin
g o
f ox
idan
t due
to:
D
osin
g m
alfu
nctio
n
P
ow
er f
ailu
re
O
xid
ant s
uppl
y ru
ns o
ut
In
crea
sed
dem
and
of r
aw
wat
er
Incr
ease
d bi
olo
gica
l gro
wth
of
pla
nts
lea
din
g to
clo
gge
d fil
ters
and
tast
e a
nd o
dou
r pr
obl
ems.
D
ecre
ased
re
mov
al o
f par
ticle
s an
d th
e ha
rmfu
l mic
ro-
orga
nism
s th
at a
dher
e to
the
m in
crea
sing
the
risk
of
illn
ess.
In
ade
quat
e re
mov
al o
f iro
n a
nd m
anga
nese
lead
ing
to
pres
enc
e of
re
d-br
ow
n a
nd
blac
kish
sus
pen
sion
s th
at
caus
e st
aini
ng a
nd ta
ste
prob
lem
s.
Inst
all a
larm
s to
wa
rn o
f int
erru
ptio
n of
dos
ing.
W
here
chl
orin
e is
dos
ed, m
easu
re r
esid
ual c
hlor
ine
leve
ls a
s fe
edb
ack
cont
rol o
f dos
ing
rate
to
acco
mm
oda
te c
han
ge in
qua
lity
of s
ourc
e w
ate
r.
Whe
re o
ther
oxi
dant
s ar
e us
ed,
test
oxi
dan
t de
ma
nd
regu
larl
y a
nd a
djus
t dos
age
rate
as
requ
ired
. H
ave
bac
k-up
po
we
r su
pply
or
tem
pora
ry d
osi
ng
equ
ipm
ent
. R
egul
arly
cal
ibra
te m
onito
ring
sys
tem
s.
Car
ry o
ut r
egul
ar m
aint
ena
nce
wo
rk o
n e
quip
men
t.
Mai
ntai
n ox
idan
t st
ocks
. O
verd
osin
g of
oxi
dan
t du
e to
dos
ing
syst
em m
alfu
nctio
n or
dec
reas
ed
dem
and
of w
ate
r.
Hea
lth a
nd
aest
hetic
impa
cts
of c
hem
ica
ls.
Inst
all f
low
pro
port
iona
l dos
ing.
M
onito
r am
oun
ts o
f che
mic
als
used
by
chec
king
leve
ls
in d
osin
g ta
nks.
W
here
chl
orin
e is
dos
ed, m
easu
re r
esid
ual c
hlor
ine
leve
ls a
s fe
edb
ack
cont
rol o
f dos
ing
rate
. W
here
oth
er o
xida
nts
are
use
d, te
st o
xid
ant
dem
and
re
gula
rly
and
adj
ust d
osag
e ra
te a
s re
quire
d.
Reg
ular
ly c
alib
rate
mon
itori
ng s
yste
ms.
C
arry
out
reg
ular
mai
nte
nanc
e w
ork
on
equ
ipm
ent.
P
re-o
xida
tion
caus
es c
yano
bact
eria
to b
urst
and
re
leas
e to
xins
. T
oxin
s ca
n h
ave
serio
us h
eal
th e
ffect
s.
Can
pro
duce
tast
e an
d od
our
pro
blem
s.
Sto
p pr
e-o
xid
atio
n. C
ons
ider
the
use
of a
n a
ppro
ved
alg
aeci
de.
Tre
atm
ent c
hem
ical
s of
po
or q
ualit
y.
Pre
-oxi
datio
n le
ss e
ffect
ive.
In
trod
uctio
n of
haz
ardo
us c
onta
min
ant
s in
to th
e w
ater
. M
ake
sure
ch
em
ical
su
pplie
r is
cer
tifie
d an
d do
not
hav
e co
ntam
inan
t le
vels
that
exc
ee
d gu
idel
ine
valu
es.
CO
AG
UL
AT
ION
, F
LO
CC
UL
AT
ION
an
d S
ED
IME
NT
AT
ION
Dos
ing
mal
fun
ctio
n ca
n re
duce
floc
form
atio
n an
d th
us
the
inef
ficie
nt r
emov
al o
f har
mfu
l mic
ro-o
rgan
ism
s,
orga
nic
mat
eria
l., c
olou
r a
nd t
urbi
dity
.
Illne
ss fr
om th
e in
gest
ion
of h
arm
ful m
icro
-org
anis
ms.
P
oor
phys
ical
qua
lity.
In
crea
sed
turb
idity
and
org
ani
c m
atte
r ca
n in
terf
ere
with
di
sinf
ectio
n an
d le
ad
to th
e fo
rmat
ion
of D
BP
s.
Mon
itor
flow
ra
te o
f coa
gula
nt w
ith a
utom
atic
or
man
ual
adju
stm
ent o
f che
mic
al d
osin
g.
Inst
all a
larm
s to
war
n of
pu
mp
failu
re.
Inst
all s
tand
by
coag
ula
nt p
umps
. M
ake
sure
that
pla
nt d
esig
n is
ade
qua
te to
sup
por
t pea
k lo
ads
. Don
’t o
per
ate
plan
t at f
low
s th
at e
xce
ed
capa
city
. C
arry
out
rou
tine
mai
nten
ance
and
ca
libra
tion
of
chem
ical
dos
ing
equ
ipm
ent
, mon
itori
ng s
yste
ms
and
alar
ms.
M
ake
sure
that
pro
ced
ures
are
in p
lace
for
aut
omat
ic
back
-up
pow
er
or e
mer
genc
y sh
ut-d
ow
n a
nd s
tart
-up.
40
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
Che
mic
al s
upp
ly r
uns
out
so
trea
tmen
t effe
ctiv
ely
stop
s.
Inab
ility
to p
rovi
de t
reat
me
nt in
crea
ses
the
risk
of i
llnes
s fr
om th
e in
gest
ion
of h
arm
ful m
icro
-org
anis
ms.
P
oor
phys
ical
qua
lity.
In
crea
sed
turb
idity
and
org
ani
c m
atte
r ca
n in
terf
ere
with
di
sinf
ectio
n an
d le
ad
to th
e fo
rmat
ion
of D
BP
s.
Mak
e su
re th
at s
uffic
ient
che
mic
al s
tock
s ar
e m
aint
ain
ed.
E
stab
lish
a pr
oce
dure
for
regu
lar
chec
king
of
stor
age
tank
leve
ls.
Hav
e a
larm
s in
the
chem
ica
l sup
ply
tank
s to
indi
cate
w
he
n le
vels
are
low
. La
rge
cha
nges
in fl
ow
rat
e or
tur
nin
g th
e pl
ant
on/
off c
an
impa
ir co
agul
atio
n a
nd fl
occu
latio
n.
Inab
ility
to p
rovi
de tr
eatm
ent
incr
ease
s th
e ri
sk o
f illn
ess
form
the
inge
stio
n of
har
mfu
l mic
ro-o
rgan
ism
s.
Poo
r ph
ysic
al q
ualit
y.
Incr
ease
d tu
rbid
ity a
nd o
rga
nic
mat
ter
can
inte
rfer
e w
ith
disi
nfec
tion
and
lea
d to
the
form
atio
n of
DB
Ps.
Est
ablis
h pr
oced
ure
for
star
t-up
an
d sh
ut-d
ow
n of
pl
ants
. E
nsur
e d
osin
g is
flo
w p
aced
and
ver
ify th
at c
han
ges
in
flow
lead
to a
ctua
l ch
ange
s in
che
mic
al d
ose
rate
s.
Poo
r co
ntro
l of p
H a
nd
alka
linity
can
re
duce
coa
gul
atio
n an
d flo
c fo
rmat
ion.
Inab
ility
to p
rovi
de tr
eatm
ent
incr
ease
s th
e ri
sk o
f illn
ess
form
the
inge
stio
n of
har
mfu
l mic
ro-o
rgan
ism
s.
Poo
r ph
ysic
al q
ualit
y.
Incr
ease
d tu
rbid
ity a
nd o
rga
nic
mat
ter
can
inte
rfer
e w
ith
disi
nfec
tion
and
lea
d to
the
form
atio
n of
DB
Ps.
Mai
nta
in o
ptim
um p
H a
nd
alka
linity
for
coag
ula
nts
and
flocc
ulan
ts a
s se
t by
ma
nufa
ctur
er’s
spe
cific
atio
ns a
nd/
or b
ase
d on
pre
vio
us e
xper
ienc
e fr
om o
pera
ting
trea
tmen
t pla
nt.
Use
jar
test
s to
est
ablis
h op
timum
pH
an
d ve
rify
dur
ing
pla
nt o
pera
tion
.
Flo
ccul
atio
n a
nd
part
icle
rem
ova
l can
be
red
uced
if
mix
ing
of c
hem
ical
s is
poo
r.
The
re is
not
en
oug
h co
ntac
t tim
e fo
r flo
c fo
rmat
ion
or
floc
does
not
set
tle p
rop
erly
.
Inab
ility
to p
rovi
de tr
eatm
ent
incr
ease
s th
e ri
sk o
f illn
ess
form
the
inge
stio
n of
har
mfu
l mic
ro-o
rgan
ism
s.
Poo
r ph
ysic
al q
ualit
y.
Incr
ease
d tu
rbid
ity a
nd o
rga
nic
mat
ter
can
inte
rfer
e w
ith
disi
nfec
tion
and
lea
d to
the
form
atio
n of
DB
Ps.
Des
ign
plan
t to
ens
ure
that
mix
ing
is a
dequ
ate
at a
ll flo
w
rate
s.
Do
not o
per
ate
pla
nt a
t flo
w r
ate
s th
at e
xce
ed d
esig
n ca
paci
ty.
If m
ixin
g is
poo
r, a
lter
the
dosi
ng p
oin
t or
intr
oduc
e lo
nge
r pi
pes
or p
ipe
ben
ds to
impr
ove
mix
ing.
M
ake
sure
that
an
y re
cycl
e st
ream
s (f
rom
filte
r ba
ckw
ash
or
slud
ge
stor
age)
are
not
inte
rfer
ing
with
flo
ccul
atio
n.
Cha
nges
in r
aw
wat
er q
ual
ity c
an o
ccur
eith
er
seas
ona
lly o
r fo
llow
ing
eve
nts
such
as
bush
fires
or
flood
s.
If do
sing
of c
oagu
lant
an
d flo
ccul
ent
is n
ot m
odifi
ed in
re
spo
nse
to w
ate
r qu
ality
ch
ange
s, tr
eatm
ent w
ill b
e im
pair
ed.
Inab
ility
to p
rovi
de tr
eatm
ent
incr
ease
s th
e ri
sk o
f illn
ess
form
the
inge
stio
n of
har
mfu
l mic
ro-o
rgan
ism
s.
Poo
r ph
ysic
al q
ualit
y.
Incr
ease
d tu
rbid
ity a
nd o
rga
nic
mat
ter
can
inte
rfer
e w
ith
disi
nfec
tion
and
lea
d to
the
form
atio
n of
DB
Ps.
Mon
itor
raw
wa
ter
qual
ity fo
r p
hys
ical
cha
nge
s (i.
e.
turb
idity
, co
lour
, pH
and
alk
alin
ity)
and
bas
ed
on ja
r te
sts,
adj
ust t
reat
men
t in
resp
onse
to th
e ch
ang
es.
Con
side
r th
e u
se o
f str
eam
ing
curr
ent d
etec
tors
wh
ere
raw
wa
ter
qua
lity
can
vary
su
bst
antia
lly.
Use
of
wro
ng
chem
ical
s ca
n im
pair
trea
tme
nt
and
cont
amin
ate
prod
uct
wat
er.
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als.
C
lear
ly la
bel c
hem
ical
sup
ply
tank
s.
Ens
ure
that
the
del
iver
y of
che
mic
als
is s
upe
rvis
ed.
Tre
atm
ent c
hem
ical
s m
ay
be
of p
oor
qual
ity.
Poo
r pe
rfor
ma
nce
of c
oagu
latio
n, fl
occu
latio
n,
sedi
men
tatio
n re
sulti
ng in
ris
k of
illn
ess
from
the
in
ges
tion
of h
arm
ful m
icro
-org
anis
ms.
In
trod
uctio
n of
haz
ardo
us c
onta
min
ant
s in
to d
rinki
ng
wat
er.
Mak
e su
re th
at th
e ch
emic
al s
upp
lier
is c
ertif
ied
and
that
th
e ch
emic
als
do n
ot h
ave
cont
amin
ants
tha
t ex
ceed
gu
idel
ine
valu
es.
E
nsur
e th
at c
hem
ical
s ar
e su
pplie
d w
ith q
ua
lity
cert
ifica
tion.
E
nsur
e th
at d
eliv
ery
of c
hem
ical
s is
sup
ervi
sed.
41
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
FIL
TR
AT
ION
(E
.G.
RA
PID
, S
LO
W S
AN
D,
MU
LT
IME
DIA
)In
ade
quat
e re
mov
al o
f tur
bidi
ty (
and
part
icle
s) a
nd
harm
ful m
icro
-org
ani
sms
can
be c
ause
d b
y:
S
udd
en in
crea
se in
flo
w r
ate
Hyd
raul
ic s
hoc
k du
e to
sud
den
ope
n an
d cl
osin
g of
val
ves
In
com
plet
e or
insu
ffici
ent
back
wa
sh (
too
sho
rt,
rate
to lo
w,
air
scou
r in
ade
quat
e or
too
shor
t)
R
apid
sta
rt u
p fo
llow
ing
back
was
hing
Fai
lure
to
redu
ce f
low
rat
es d
urin
g ba
ckw
ash
ing
Med
ia d
isp
lace
men
t, cr
acki
ng o
r lo
ss
M
edia
blo
ckag
e in
clud
ing
mu
dba
lls
T
rapp
ing
of a
ir bu
bbl
es in
clud
ing
air
bin
din
g
Inab
ility
to p
rovi
de tr
eatm
ent
incr
ease
s th
e ri
sk o
f illn
ess
form
the
inge
stio
n of
har
mfu
l mic
ro-o
rgan
ism
s.
Poo
r ph
ysic
al q
ualit
y.
Incr
ease
d tu
rbid
ity a
nd o
rga
nic
mat
ter
can
inte
rfer
e w
ith
disi
nfec
tion
and
lea
d to
the
form
atio
n of
DB
Ps.
Mak
e su
re th
at p
lant
des
ign
is a
deq
uate
to s
upp
ort p
eak
loa
ds. D
o no
t ope
rate
filte
rs a
t ra
tes
that
exc
eed
des
ign
capa
city
. C
arry
out
rou
tine
mai
nten
ance
and
ca
libra
tion
of
mon
itori
ng s
yste
ms
and
ala
rms.
H
ave
proc
edur
es in
pla
ce fo
r au
tom
atic
bac
k-up
of
pow
er
or e
mer
genc
y sh
ut-d
ow
n/st
art-
up.
Avo
id s
udd
en c
han
ges
in fl
ow
rat
e in
clud
ing
duri
ng
oper
atio
n of
val
ves.
Mon
itor
bac
kwas
hing
to e
nsu
re b
ackw
ash
ra
tes
are
ade
quat
e
E
nsur
e ba
ckw
ash
times
are
suf
ficie
nt
E
ven
dist
ribu
tion
of a
ir sc
our
and
bac
kwa
sh f
low
s R
educ
e flo
w r
ate
s du
ring
back
wa
shin
g a
nd a
void
ra
pid
star
t-up
of f
ilter
s fo
llow
ing
bac
kwa
shin
g or
on
ret
urn
to
serv
ice.
If
poss
ible
, use
a fi
lter
wa
ste
faci
lity
to r
emov
e w
ate
r pr
oduc
ed d
urin
g be
d rip
eni
ng
(fol
low
ing
back
wa
sh).
U
nder
take
filte
r as
sess
men
ts.
Mon
itor
clea
n be
d h
eadl
oss.
P
OW
DE
RE
D/G
RA
NU
LA
R A
CT
IVA
TE
D C
AR
BO
NT
here
ma
y be
inad
equa
te r
emov
al o
f:
cy
ano
bact
eria
l (bl
ue-
gre
en a
lgae
) to
xins
Tas
te a
nd o
dour
com
poun
ds (
geos
min
an
d M
IB)
P
estic
ides
an
d or
gani
c co
mp
oun
ds
N
atur
ally
occ
urrin
g or
gan
ic m
atte
r, in
crea
sin
g tu
rbid
ity
Cya
nob
acte
rial t
oxin
s ca
n h
ave
serio
us h
eal
th e
ffect
s.
Tas
te a
nd o
dour
pro
ble
ms.
H
ealth
an
d ae
sthe
tic im
pact
of
chem
ica
ls.
Incr
ease
d tu
rbid
ity a
nd o
rga
nic
mat
ter
can
inte
rfer
e w
ith
disi
nfec
tion
and
lea
d to
the
form
atio
n of
DB
Ps
– ru
n ris
k of
illn
ess
from
bot
h.
Det
erm
ine
abso
rptiv
e ca
paci
ty o
f PA
C/G
AC
. U
se a
ppr
opri
ate
sour
ce o
f PA
C (
seek
exp
ert a
dvic
e).
CH
LO
RIN
AT
ION
(IN
CL
UD
ING
SE
CO
ND
AR
Y C
HL
OR
INA
TIO
N)
Dos
ing
mal
fun
ctio
n du
e to
eq
uipm
ent f
ailu
re o
r po
wer
fa
ilure
. P
ossi
ble
inte
rrup
tion
to c
hlor
inat
ion
(chl
orin
e un
der
dosi
ng,
chl
orin
e ov
erd
osi
ng).
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
O
verd
osin
g co
uld
caus
e:
Exp
osur
e to
ha
rmfu
l lev
els
of c
hlor
ine.
T
aste
and
odo
ur p
rob
lem
s.
Exp
osur
e to
pot
entia
lly h
arm
ful l
evel
s of
DB
Ps.
Use
con
tinu
ous
(ala
rme
d) m
oni
tori
ng o
f the
dos
ing
syst
em to
war
n o
f the
inte
rrup
tion
to c
hlor
inat
ion.
E
nsur
e a
utom
atic
shu
t-do
wn
if su
pply
of c
hlor
inat
ion
fails
. C
arry
out
rou
tine
perf
orm
ance
che
cks
and
mai
nte
nanc
e of
dos
ing
equi
pm
ent (
incl
. dos
ing
lines
, pum
ps
and
chlo
rine
cyl
ind
er c
han
geov
er s
yste
ms)
. R
egul
arly
cal
ibra
te d
osin
g e
qui
pmen
t an
d a
utom
atic
m
onito
ring
syst
ems.
H
ave
bac
k-up
po
we
r sy
stem
s or
acc
ess
to te
mpo
rary
do
sing
equ
ipm
ent.
Inst
all s
tand
by
dosi
ng e
quip
men
t inc
ludi
ng p
umps
.
42
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
Dis
infe
ctio
n ch
emic
al s
upp
ly r
uns
out.
Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
Hav
e ro
utin
e p
roce
dur
es fo
r m
aint
ain
ing
fre
sh c
hlor
ine
stoc
ks a
nd o
n-si
te s
tora
ge o
f su
ffici
ent s
uppl
y.
Ens
ure
aut
oma
tic s
hut-
dow
n if
supp
ly o
f chl
orin
atio
n fa
ils.
Inst
all a
larm
s o
n ch
emic
al s
uppl
y ta
nks
or c
ylin
der
sc
ales
. C
arry
out
rou
tine
chec
ks o
f st
orag
e le
vels
. P
erfo
rm r
outin
e m
aint
ena
nce
of c
hlor
ine
cylin
der
chan
geov
er s
yste
ms.
C
hlor
ine
unde
rdos
ing
(inad
equa
te c
onta
ct ti
me)
ma
y oc
cur
due
to in
crea
sed
chlo
rin
e de
ma
nd in
ra
w w
ater
or
incr
ease
d w
ate
r flo
ws.
C
hang
es in
wa
ter
qual
ity c
oul
d be
sea
son
al o
r du
e to
ev
ents
suc
h as
hea
vy r
ain
or b
ush
fires
.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
In
stal
l flo
w p
ropo
rtio
nal d
osin
g to
acc
omm
oda
te
chan
ges
in fl
ow
or
resi
dua
l mon
itori
ng w
ith fe
edba
ck
cont
rol o
f chl
orin
e do
se r
ate
to a
ccom
mod
ate
bot
h ty
pes
of
fluc
tuat
ion.
If
raw
wa
ter
turb
idity
or
colo
ur c
han
ges
subs
tant
ially
, ch
eck
chlo
rine
dem
and
and
adj
ust d
ose
rate
if
nece
ssar
y.
C
hlor
ine
over
dos
ing
ma
y oc
cur
due
to d
ecre
ased
ch
lori
ne d
ema
nd in
ra
w w
ate
r or
dec
reas
ed w
ater
flo
ws.
Exp
osur
e to
ha
rmfu
l lev
els
of c
hlor
ine.
T
aste
s an
d od
our
pro
blem
s.
Exp
osur
e to
hig
h le
vels
of
DB
Ps.
Inst
all f
low
pro
port
iona
l dos
ing
to a
ccom
mo
date
ch
ange
s in
flo
w o
r re
sid
ual m
onito
ring
with
feed
back
co
ntro
l of c
hlor
ine
dose
rat
e to
acc
omm
odat
e b
oth
typ
es
of fl
uctu
atio
n.
Ra
w w
ater
turb
idity
/col
our
cha
nges
su
bsta
ntia
lly, c
heck
ch
lori
ne d
ema
nd a
nd
adju
st d
ose
rate
nec
ess
ary.
Lo
w fr
ee c
hlo
rine
res
idua
l in
the
dist
ribu
tion
syst
em
redu
ces
prot
ectio
n ag
ains
t fae
cal c
onta
min
atio
n an
d fr
ee
livin
g or
gan
ism
s.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
S
et d
osin
g to
pro
vid
e ad
equ
ate
conc
ent
ratio
n to
ach
ieve
in
itia
l dis
infe
ctio
n an
d w
her
e re
quire
d, fr
ee c
hlor
ine
resi
dua
ls w
ith th
e di
strib
utio
n sy
stem
. If
raw
wa
ter
turb
idity
or
colo
ur c
han
ges
subs
tant
ially
ch
eck
chlo
rine
dem
and
and
adj
ust d
ose
rate
if
nece
ssar
y.
Tre
atm
ent c
hem
ical
s m
ay
be
of p
oor
qual
ity
com
prom
isin
g ef
fect
iven
ess
of
disi
nfec
tion.
Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
Intr
oduc
tion
of h
azar
dous
con
tam
ina
nts
into
the
wat
er.
Mak
e su
re th
at c
hem
ica
l sup
plie
r is
cer
tifie
d an
d th
at
chem
ical
s do
not
hav
e co
nta
min
ant
s th
at e
xcee
d gu
idel
ine
valu
es.
43
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
OZ
ON
AT
ION
Ozo
natio
n m
ay
be in
terr
upt
ed d
ue to
equ
ipm
ent
mal
func
tion,
exh
aust
ion
or p
ow
er
failu
re.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
U
se c
ontin
uou
s (a
larm
ed)
mo
nito
ring
of t
he d
osin
g sy
stem
to w
arn
of t
he in
terr
uptio
n to
ozo
natio
n.
Ens
ure
aut
oma
tic s
hut-
dow
n if
supp
ly o
f ozo
nat
ion
fails
. C
arry
out
rou
tine
perf
orm
ance
che
cks
and
mai
nte
nanc
e of
dos
ing
equi
pm
ent i
ncl.
pum
ps.
Reg
ular
ly c
alib
rate
dos
ing
eq
uipm
ent a
nd
aut
omat
ic
mon
itorin
g sy
stem
s.
Hav
e b
ack-
up p
ow
er
syst
ems
or a
cces
s to
tem
pora
ry
dosi
ng e
quip
men
t. In
crea
sed
wat
er
flow
s ca
n le
ad
to u
nder
dos
ing
(ina
deq
uate
co
ntac
t tim
e).
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
M
onito
r re
sidu
al o
zone
leve
ls a
t out
let o
f con
tact
tank
w
ith a
larm
to w
arn
if re
sid
uals
not
det
ecta
ble.
R
egul
arly
cal
ibra
te a
utom
atic
mon
itorin
g sy
stem
s.
Mon
itor
flow
ra
tes
and
adj
ust
dose
rat
es a
s re
quire
d.
Hig
h pH
(>
8) o
r hi
gh tu
rbid
ity c
an r
esu
lt in
un
derd
osin
g.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
O
n-lin
e m
onito
ring
of p
H,
turb
idity
, co
lour
and
flo
w r
ate
with
ala
rm to
war
n if
oper
atio
nal
lim
its a
re e
xcee
ded
. U
se p
re-f
iltra
tion
to r
educ
e tu
rbid
ity b
elo
w 1
NT
U a
nd
pre-
trea
tme
nt to
red
uce
natu
ral o
rgan
ic m
atte
r.
Bro
mid
e m
ay
be
pres
ent
in r
aw
wat
er.
Exc
essi
ve fo
rmat
ion
of b
rom
inat
ed D
BP
s.
Adj
ust
wat
er a
lkal
inity
to r
edu
ce b
rom
ate
form
atio
n.
Mak
e su
re th
at o
zone
is u
sed
with
in p
re-s
et d
oses
. U
LT
RA
VIO
LE
T R
AD
IAT
ION
D
isin
fect
ion
ma
y be
inte
rrup
ted
by
equi
pme
nt
mal
func
tion
or p
ow
er
failu
re.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
U
se c
ontin
uou
s (a
larm
ed)
mo
nito
ring
of t
he U
V
oper
atio
n an
d tr
ansm
itted
dos
e.
Car
ry o
ut r
outin
e m
aint
enan
ce in
cl. c
lean
ing
of U
V
lam
ps/s
leev
es a
nd r
epl
acem
ent
of U
V la
mps
at t
he e
nd
of th
eir
exp
ecte
d lif
e.
Reg
ular
ly in
spec
t UV
sys
tem
and
re
plac
e bu
rnt o
ut
lam
ps.
Reg
ular
ly c
alib
rate
aut
omat
ic m
onito
ring
syst
ems.
H
ave
bac
k-up
po
we
r sy
stem
s av
aila
ble.
In
ade
quat
e irr
adi
atio
n (d
isin
fect
ion)
ma
y be
due
to
incr
eas
ed tu
rbid
ity o
r co
lour
in r
aw
wat
er o
r in
crea
sed
flow
s.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
U
se p
re-f
iltra
tion
to r
educ
e tu
rbid
ity to
be
low
1 N
TU
O
pera
te fl
ow
rat
es to
with
in t
he U
V li
ght s
yste
m.
SO
FT
EN
ING
Sof
tene
d w
ate
r ca
n be
cor
rosi
ve a
nd le
ach
chem
ical
s fr
om p
ipes
. H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s, e
.g. c
oppe
r.
Mix
sof
tene
d w
ater
with
ble
ndi
ng w
ater
s (u
nsof
tene
d w
ater
) or
rec
arbo
nat
e th
e w
ater
to r
educ
e co
rros
iven
ess.
S
ofte
nin
g of
ve
ry h
ard
wat
ers
usin
g io
n e
xch
ang
e ca
n le
ad
to in
cre
ased
con
cent
ratio
ns o
f sod
ium
in th
e w
ater
. U
nacc
epta
ble
tast
es.
Mix
sof
tene
d w
ater
with
ble
ndi
ng w
ater
s (u
nsof
tene
d w
ater
) or
rec
arbo
nat
e th
e w
ater
to r
educ
e un
acce
pta
ble
tast
es.
44
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
Whe
re li
me
softe
nin
g is
use
d in
corr
ect d
osin
g or
poo
r pH
con
tro
l can
red
uce
the
effic
ienc
y of
the
proc
ess
and
ma
y in
terf
ere
with
oth
er tr
eatm
ent p
roce
sse
s (e
.g. i
f us
ed in
con
jun
ctio
n w
ith c
oag
ulat
ion,
floc
cula
tion
and
se
dim
enta
tion)
.
Incr
ease
d ha
rdne
ss.
Pos
t sof
teni
ng
prec
ipita
tion
of e
xces
s lim
e an
d fo
rmat
ion
of c
alci
um c
arb
onat
e d
epos
its.
Inte
rfer
ence
with
coa
gula
tion,
floc
cula
tion
and
sedi
men
tatio
n ca
n re
duc
e th
e r
emov
al o
f har
mfu
l mic
ro-
orga
nism
s, le
ad
to p
oor
ph
ysic
al q
ual
ity (
e.g.
turb
idity
) an
d in
terf
ere
with
dis
infe
ctio
n.
Mon
itor
dos
e ra
tes
of li
me.
M
onito
r p
H s
ofte
ning
pro
cess
. M
ake
sure
that
suf
ficie
nt c
hem
ical
sto
cks
are
mai
nta
ine
d.
Est
ablis
h a
pro
cedu
re fo
r re
gula
r ch
ecki
ng o
f st
orag
e ta
nk le
vels
. H
ave
ala
rms
in th
e ch
emic
al s
upp
ly ta
nks
to in
dica
te
wh
en
tank
s ar
e lo
w.
Whe
re li
me
softe
nin
g is
use
d, tr
eatm
ent c
hem
ical
s m
ay
be o
f po
or q
ualit
y.
Intr
oduc
tion
of h
azar
dous
che
mic
als
into
ra
w w
ater
. M
ake
sure
that
che
mic
al s
upp
lier
is c
ertif
ied
and
the
chem
ical
s do
not
hav
e co
nta
min
ant
s th
at e
xcee
d gu
idel
ine
valu
es.
O
rgan
ic m
ater
ial m
ay
accu
mu
late
in r
esin
s (w
her
e us
ed)
and
supp
ort m
icro
bial
gro
wth
. P
oor
trea
tmen
t ef
ficie
ncy.
T
aste
and
odo
ur p
rob
lem
s.
Pre
-tre
at w
ate
r to
rem
ove
org
anic
mat
ter
befo
re
softe
ning
. K
eep
ma
inte
nanc
e up
-to-
date
, in
clu
din
g re
ge
nera
tion
of
resi
n.
Sou
rce
wat
er v
ery
har
d (>
200
mg
calc
ium
car
bon
ate)
. S
cale
bui
ld-u
p on
trea
tmen
t equ
ipm
ent a
nd p
ipin
g.
Kee
p w
ater
sof
teni
ng
equi
pmen
t w
ell m
aint
ain
ed
and
rem
ove
scal
e if
nece
ssar
y.
PR
OT
EC
TE
D S
ER
VIC
E R
ES
ER
VO
IR (
CO
VE
RE
D S
TO
RA
GE
TA
NK
)A
nim
als/
bird
s ca
n en
ter
thro
ugh
faul
ts a
nd
cont
amin
ate
the
wat
er w
ith t
heir
drop
pin
gs.
If an
imal
s dr
ow
n, th
ere
will
be
a hi
ghe
r le
vel o
f ha
rmfu
l m
icro
-org
anis
ms
pres
ent.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
P
ossi
ble
od
ours
. C
heck
tank
ro
of
regu
larl
y fo
r h
oles
and
dam
age
. M
ake
sure
all
ope
nin
gs a
nd o
verf
low
s ar
e sc
reen
ed/s
eal
ed.
M
aint
ain
dis
infe
ctan
t res
idua
l with
in th
e ta
nk.
Ani
mal
/bird
dro
ppin
gs m
ay
be
wa
shed
into
sto
rag
es in
ra
inw
ate
r, e
nte
ring
thro
ugh
faul
ts in
the
stor
age
roo
f or
from
inte
rna
lly d
rain
ing
roof
s.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
Che
ck r
oof
of t
ank
reg
ular
ly f
or h
oles
an
d d
amag
e.
Pre
vent
inte
rna
l dra
inag
e fr
om th
e ro
of in
to th
e ta
nk.
Mai
nta
in d
isin
fect
ant r
esid
ual i
nsid
e th
e ta
nk.
Una
utho
rised
hum
an a
cces
s, s
uch
as s
wim
min
g in
the
stor
age
tank
s, c
an c
ause
mic
robi
al c
onta
min
atio
n
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
M
ake
sure
that
all
fenc
es, t
ow
ers
and
roof
ha
tche
s ar
e al
wa
ys lo
cke
d.
Mai
nta
in d
isin
fect
ant r
esid
ual w
ithin
the
tank
. H
igh
chlo
rine
leve
ls m
ay
ent
er
the
dist
ribut
ion
syst
em if
th
ere
is p
oor
mix
ing
afte
r di
sin
fect
ion
of s
tora
ges.
Ir
ritat
ion
of m
ucou
s m
embr
anes
. T
aste
and
odo
ur p
rob
lem
s.
Whe
n di
sinf
ectin
g st
orag
es, m
ake
sure
that
ther
e is
ad
equ
ate
mix
ing.
M
easu
re fr
ee c
hlor
ine
resi
dual
s in
the
stor
age
outle
t fo
llow
ing
chlo
rina
tion.
R
e-su
spen
sio
n o
f sed
imen
ts c
onta
inin
g sl
ime
s an
d od
our
pro
duci
ng
mic
ro-o
rgan
ism
s m
ay
occu
r.
Odo
urs.
In
crea
sed
turb
idity
and
re
duct
ion
of d
isin
fect
ant
res
idu
al.
Min
imiz
eent
ry o
f dus
t. In
spec
t sto
rag
es r
egu
larly
an
d cl
ean
wh
en n
eces
sary
. V
and
alis
m o
r sa
bota
ge m
ay
pol
lute
the
wat
er w
ith
chem
ical
s or
mic
rob
es o
r da
mag
e e
quip
me
nt a
nd
infr
astr
uctu
re.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s.
Inte
rrup
tion
of s
upp
ly.
Mak
e su
re a
ll fe
nces
, to
wer
s, la
dde
rs a
nd
roof
hat
ches
ar
e al
wa
ys lo
cked
. R
epai
r an
y d
am
ages
to s
ecu
rity
devi
ces.
If
vand
alis
m o
r sa
bota
ge is
su
spec
ted,
take
sto
rage
out
of
ser
vice
unt
il in
vest
igat
ions
are
com
ple
te a
nd s
amp
ling
indi
cate
s th
at w
ater
is s
afe.
45
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
UN
PR
OT
EC
TE
D S
ER
VIC
E R
ES
ER
VO
IR (
UN
CO
VE
RE
D S
TO
RA
GE
TA
NK
)A
nim
als/
bird
s ca
n en
ter
thro
ugh
faul
ts a
nd
cont
amin
ate
the
wat
er w
ith t
heir
drop
pin
gs.
If an
imal
s dr
ow
n, th
ere
will
be
a hi
ghe
r le
vel o
f ha
rmfu
l m
icro
-org
anis
ms
pres
ent.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
P
ossi
ble
od
ours
. P
rovi
de
fenc
ing
to r
educ
e an
imal
acc
ess.
C
heck
tank
re
gul
arly
for
dea
d an
imal
s an
d de
bris
. M
aint
ain
dis
infe
ctan
t res
idua
l with
in th
e ta
nk.
Con
side
r us
ing
dis
infe
ctio
n if
not a
lread
y d
one
. A
nim
al/b
ird d
ropp
ings
ma
y b
e w
ash
ed in
to s
tora
ges
in
rain
wa
ter,
ent
erin
g th
roug
h fa
ults
in th
e st
ora
ge r
oof o
r fr
om in
tern
ally
dra
inin
g ro
ofs.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
M
ake
sure
that
all
fenc
es, t
ow
ers,
ladd
ers
and
roof
ha
tche
s ar
e al
wa
ys lo
cked
. C
onsi
der
usin
g d
isin
fect
ion
if no
t alre
ady
do
ne.
Mai
nta
in d
isin
fect
ant r
esid
ual w
ithin
the
tank
. G
row
th o
f cya
nob
acte
ria
(blu
e-g
ree
n al
gae
) a
nd o
ther
al
gae
ca
n be
a p
robl
em w
here
sto
rage
tank
s ar
e op
en
to
sunl
ight
.
Som
e sp
ecie
s of
cya
nob
acte
ria
prod
uce
toxi
ns th
at h
ave
serio
us h
ealth
effe
cts.
T
aste
and
odo
ur p
rob
lem
s fr
om
cya
nob
acte
ria.
Mai
nta
in d
isin
fect
ant r
esid
ual w
ithin
the
tank
. C
onsi
der
usin
g d
isin
fect
ion
if no
t alre
ady
do
ne.
Spr
ay
drift
s fr
om n
earb
y fa
rmin
g ac
tiviti
es in
cl.
pest
icid
es a
nd a
gric
ultu
ral c
hem
ical
s as
we
ll as
dirt
and
ot
her
win
d b
orne
de
bris
ca
n en
ter
stor
age.
Ph
ysic
al c
onta
min
atio
n of
the
wat
er.
Hea
lth im
pact
s of
che
mic
als.
C
heck
tank
re
gul
arly
for
deb
ris.
Wor
k w
ith lo
cal c
omm
unity
to
man
age
aer
ial s
pra
ying
ac
tiviti
es s
o as
to
avoi
d co
nta
min
atio
n of
rai
nw
ater
tank
s.
Bus
hfire
ma
y le
ad to
ret
arda
nts
and
larg
e a
mou
nts
of
ash
ente
rin
g st
orag
e.
Tas
te a
nd o
dour
pro
ble
ms.
H
ealth
an
d ae
sthe
tic im
pact
of
chem
ica
ls.
Poo
r ph
ysic
al q
ualit
y of
wat
er.
Che
ck ta
nk r
eg
ular
ly fo
r d
ebris
. If
nece
ssar
y, fl
ush
and
cle
an ta
nk a
fter
a bu
shfir
e.
Hig
h ch
lori
ne r
esid
uals
ma
y e
nter
the
dist
ribut
ion
syst
em
if th
ere
is p
oor
mix
ing
afte
r di
sinf
ectio
n in
sto
rage
s.
Irrit
atio
n of
muc
ous
mem
bran
es.
Tas
te a
nd o
dour
pro
ble
ms.
W
hen
disi
nfec
ting
stor
ages
, mak
e su
re th
at th
ere
is
ade
quat
e m
ixin
g.
Mea
sure
free
chl
orin
e re
sidu
als
in th
e st
orag
e ou
tlet
follo
win
g ch
lori
natio
n.
Re-
susp
ensi
on
of s
edim
ents
con
tain
ing
slim
es
and
odo
ur p
rodu
cin
g m
icro
-org
anis
ms
ma
y oc
cur.
O
dour
s.
Incr
ease
d tu
rbid
ity a
nd r
edu
ctio
n of
dis
infe
cta
nt r
esid
ual
. M
inim
izee
ntry
of d
ust.
Insp
ect s
tora
ges
reg
ula
rly a
nd
clea
n w
hen
nec
essa
ry.
Van
dal
ism
or
sabo
tage
ma
y p
ollu
te th
e w
ater
with
ch
emic
als
or m
icro
bes
or
dam
age
equ
ipm
ent
and
in
fras
truc
ture
.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s.
Inte
rrup
tion
of s
upp
ly.
Mak
e su
re a
ll fe
nces
, to
wer
s, la
dde
rs a
nd
roof
hat
ches
ar
e al
wa
ys lo
cked
. R
epai
r an
y d
am
ages
to s
ecu
rity
devi
ces.
If
vand
alis
m o
r sa
bota
ge is
su
spec
ted,
take
sto
rage
out
of
ser
vice
unt
il in
vest
igat
ions
are
com
ple
te a
nd s
amp
ling
indi
cate
s th
at w
ater
is s
afe.
46
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
DIS
TR
IBU
TIO
N S
YS
TE
M
Pip
e b
urst
s an
d le
aks
can
inte
rrup
t the
wat
er
supp
ly.
Con
tam
inat
ion
can
occu
r w
her
e w
ate
r pi
pes
are
bel
ow
or
clo
se to
sto
rm w
ater
or
sew
age
pip
es o
r in
are
as w
ith
sept
ic ta
nks,
lead
ing
to m
icro
bial
and
che
mic
al
cont
amin
atio
n.
Ent
ry o
f so
il m
ay in
crea
se tu
rbid
ity.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
A
esth
etic
pro
blem
s as
soci
ate
d w
ith tu
rbid
ity.
Loss
of
wat
er.
Inte
rrup
tion
to s
upp
ly.
Est
ablis
h pr
even
tativ
e m
ain
tena
nce
pro
gram
me
to
redu
ce li
kelih
ood
of p
ipe
burs
ts o
r va
lve
failu
res.
K
eep
inva
sive
tree
s a
wa
y fr
om
pip
es.
Est
ablis
h re
spon
se a
nd r
epa
ir p
roce
dur
es to
m
inim
izet
he ti
me
take
n to
iso
late
a p
ipe
bur
st.
Use
diff
ere
nt c
olo
ured
pip
e-w
ork
for
pota
ble
and
non
-po
tab
le w
ater
and
ma
inta
in lo
we
r pr
essu
res
in n
on-
pota
ble
su
pplie
s th
an in
pot
able
sup
plie
s.
Mai
nta
in s
epar
atio
n d
ista
nces
from
se
wa
ge/s
torm
wat
er
syst
ems.
P
rovi
de
suita
ble
pro
tect
ion
for
pipe
s in
dra
ina
ge o
r riv
er
cros
sin
gs. I
sola
te th
ese
cros
sing
s d
urin
g flo
odi
ng.
M
icro
bial
or
chem
ical
con
tam
inan
ts c
an e
nte
r th
e w
ater
su
pply
sys
tem
thr
oug
h cr
oss-
conn
ectio
ns o
r ba
ckflo
w.
Illne
ss fr
om th
e in
gest
ion
of h
arm
ful m
icro
-org
anis
ms.
H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s.
Pre
vent
bac
kflo
w –
inst
all
back
flow
pre
vent
ion
devi
ces.
A
void
cro
ss-c
onn
ectio
ns b
etw
een
drin
king
wat
er a
nd
othe
r w
ater
an
d flu
id s
yste
ms.
M
aint
ain
pos
itive
pre
ssur
e in
the
dis
trib
utio
n sy
stem
. W
ater
can
be
cont
amin
ate
d d
urin
g re
pair
and
mai
nte
nanc
e.
Ent
ry o
f so
il ca
n in
crea
se tu
rbid
ity.
Illne
ss fr
om th
e in
gest
ion
of h
arm
ful m
icro
-org
anis
ms.
A
esth
etic
pro
blem
s as
soci
ate
d w
ith tu
rbid
ity.
Est
ablis
h pr
oced
ures
for
mai
nten
anc
e a
nd r
epa
ir th
at
min
imiz
ethe
like
lihoo
d of
con
tam
inat
ion.
A
fter
repa
ir, fl
ush
thor
ough
ly a
nd w
her
e ne
cess
ary,
ch
lori
nate
the
pip
es.
Inad
equ
ate
disi
nfec
tion
or fl
ushi
ng
befo
re
com
mis
sio
ning
of n
ew
mai
ns r
esul
ts in
co
nta
min
atio
n –
chem
ical
an
d m
icro
bial
co
nta
min
atio
n.
Pre
senc
e of
so
il ca
n in
crea
se tu
rbid
ity.
Illne
ss fr
om th
e in
gest
ion
of h
arm
ful m
icro
-org
anis
ms.
H
ealth
an
d ae
sthe
tic im
pact
of
chem
ica
l con
tam
inan
ts.
Aes
thet
ic p
robl
ems
asso
ciat
ed
with
turb
idity
.
Est
ablis
h st
and
ard
proc
edur
es fo
r co
mm
issi
oni
ng
new
m
ains
, inc
lud
ing
disi
nfec
tion
and
flus
hin
g.
Sto
re n
ew
pip
es
and
fittin
gs w
ith o
peni
ngs
seal
ed.
Con
tam
inat
ed
wat
er m
ay
ente
r th
e sy
stem
dur
ing
flood
ing,
par
ticul
arly
thro
ugh
abov
e gr
oun
d h
ydra
nts
and
air
valv
es. M
icro
bial
an
d ch
emic
al c
ont
amin
atio
n po
ssib
le
Pre
senc
e of
so
il m
ay
incr
eas
e tu
rbid
ity.
Illne
ss fr
om th
e in
gest
ion
of h
arm
ful m
icro
-org
anis
ms.
H
ealth
an
d ae
sthe
tic im
pact
of
chem
ica
l con
tam
inan
ts.
Aes
thet
ic p
robl
ems
asso
ciat
ed
with
turb
idity
.
Pro
tect
pip
es in
dra
inag
e an
d r
iver
cro
ssin
gs.
Isol
ate
dra
inag
e or
riv
er c
ross
ing
dur
ing
floo
din
g.
If co
ntam
inat
ed
by
flood
wa
ter,
flus
h pi
pes
thor
ough
ly
and
wh
ere
poss
ible
, ch
lorin
ate.
Rai
sed
tem
pera
ture
s (e
.g. 2
5-30
oC
) in
long
, ab
ove
grou
nd p
ipe
lines
can
sup
port
the
gro
wth
of s
ome
orga
nism
s.
Ser
ious
illn
ess
thro
ugh
inha
latio
n or
co
ntac
t. C
onsi
der
usin
g c
hlor
amin
atio
n to
pro
vide
a p
ersi
sten
t re
sid
ual.
Leac
hin
g fr
om c
emen
t pip
es, p
artic
ula
rly
dur
ing
peri
ods
of lo
w fl
ow
, ca
n ca
use
a hi
gh
pH.
Ver
y hi
gh
pH (
>10
) ca
n da
ma
ge h
ous
eho
ld p
lum
bin
g
pH >
11
can
irrita
te e
yes
and
skin
. F
lush
pip
es d
urin
g p
erio
ds o
f ver
y lo
w fl
ow
In
vest
igat
e w
ays
to in
crea
se f
low
s th
roug
h se
ctio
ns o
f th
e pi
pe.
C
hang
es in
flo
w o
r in
cre
ased
con
cent
ratio
ns o
f di
sinf
ecta
nt c
an
caus
e sl
ough
ing
and
re-
susp
ensi
on o
f bi
ofilm
s.
Incr
ease
d tu
rbid
ity.
Dis
colo
ured
wat
er.
Tas
te a
nd o
dour
pro
ble
ms.
Flu
sh m
ains
be
fore
cha
nge
s in
flo
w o
r in
crea
sed
conc
ent
ratio
ns o
f dis
infe
cta
nt c
ould
lea
d to
slo
ughi
ng
of
biof
ilms.
P
ump
failu
re
Inte
rrup
tion
to s
upp
ly.
Hav
e b
ack-
up s
yste
ms
avai
labl
e fo
r pu
mpi
ng
faci
litie
s (a
ltern
ativ
e po
we
r su
ppl
y an
d s
pare
pum
ps).
47
Haz
ard
R
isk
Co
rre
ctiv
e ac
tio
n/s
Dea
d-en
d m
ains
and
low
wat
er fl
ow
s ca
n le
ad to
st
agna
nt w
ate
r an
d lo
ss o
f res
idu
al c
hlor
ine.
U
nacc
epta
ble
odo
urs.
In
vest
igat
e w
ays
to in
crea
se f
low
s th
roug
h se
ctio
ns o
f th
e pi
pe.
R
educ
e d
ead
end
s U
nsui
tabl
e co
atin
gs a
nd
mat
eria
ls c
an
leac
h ch
emic
als
or s
upp
ort b
acte
rial g
row
th.
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als.
T
aste
and
odo
ur p
rob
lem
s.
Use
on
ly m
ater
ials
app
rove
d fo
r us
e in
dri
nkin
g w
ater
.
Van
dal
ism
or
sabo
tage
ma
y p
ollu
te th
e w
ater
with
ch
emic
als
or m
icro
bes
or
dam
age
equ
ipm
ent
and
in
fras
truc
ture
.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s.
Inte
rrup
tion
to s
upp
ly.
Mak
e su
re th
at p
oten
tially
acc
essi
ble
com
po
nent
s of
di
strib
utio
n sy
stem
s ar
e ke
pt s
ecur
e a
nd a
re lo
cked
.
HO
US
EH
OL
D C
ON
NE
CT
ION
S
Hou
seho
ld p
lum
bin
g ca
n:
Leac
h ch
emic
als
that
hav
e h
eal
th im
pac
ts o
r ca
use
tast
es a
nd o
dour
s.
Sup
por
t mic
rob
ial g
row
th th
at c
an a
lso
caus
e ta
stes
and
od
our
s.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s.
Edu
cate
hou
seho
lder
s an
d pl
umbe
rs a
bout
saf
e pl
umbi
ng
mat
eria
ls a
nd in
sta
llatio
n.
Hou
seho
ld p
lum
bin
g ca
n b
ecom
e co
rro
ded
thro
ugh
in
corr
ect i
nsta
llatio
n or
from
act
ion
of w
ater
sup
ply
on
fittin
gs.
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als
Edu
cate
hou
seho
lder
s an
d pl
umbe
rs a
bout
saf
e pl
umbi
ng
mat
eria
ls a
nd in
sta
llatio
n.
Bac
kflo
w fr
om h
ouse
hol
d p
lum
bin
g de
vice
s or
wat
er
stor
ages
(e.
g. r
ain
wa
ter
tank
s, s
wim
min
g p
ools
, gar
den
pon
ds)
can
cont
amin
ate
drin
king
wat
er s
yste
ms.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s.
Inst
all b
ack-
flow
pre
vent
ion
devi
ces.
48
H
azar
d
Ris
kC
orr
ect
ive
acti
on
/sC
OM
MU
NIT
Y S
TA
ND
PIP
ES
B
ackf
low
from
tan
kers
con
nect
ing
to s
tand
pip
es c
an
lea
d to
mic
robi
al a
nd
chem
ica
l con
tam
inat
ion
of t
he
wat
er.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
H
ealth
or
aest
het
ic im
pact
of c
hem
ical
s.
Mak
e su
re th
at th
ere
is e
noug
h po
sitiv
e pr
essu
re a
t the
fil
ling
poin
t to
redu
ce p
ote
ntia
l bac
kflo
w.
Inst
all b
ackf
low
pre
vent
ion
valv
es.
Wat
er s
tand
ing
at a
cces
s po
ints
can
attr
act b
irds
and
anim
als,
rai
sin
g ve
ctor
and
dis
ease
co
ncer
ns.
Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
M
ake
sure
that
taps
are
sel
f clo
sin
g to
min
imiz
ew
ater
lo
ss.
Scr
een
end
of
stan
dpip
es to
pre
vent
the
ent
ry o
f bir
ds,
inse
cts,
etc
.
Ere
ct fe
ncin
g a
roun
d th
e fil
ling
poi
nt to
con
tro
l acc
ess
of
cattl
e, e
tc.
Mak
e su
re a
rea
arou
nd th
e fil
ling
poin
t has
goo
d dr
aina
ge.
R
egul
arly
cle
an/
disi
nfec
t the
tap/
stan
dpi
pe e
nd.
Dam
age
to th
e fi
lling
poi
nt c
an in
terr
upt
sup
ply
and
allo
w
entr
y of
con
tam
inat
ion.
Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als.
P
ossi
ble
inte
rrup
tion
to s
upp
ly.
Inst
all c
over
s to
pro
tect
the
taps
.
Con
tain
ers
use
d to
col
lect
and
tran
spor
t the
wat
er m
ay
be c
onta
min
ated
. Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als.
E
duca
te th
e pu
blic
re
gard
ing
the
sele
ctio
n an
d ca
re o
f co
ntai
ners
and
pro
tect
ion
of w
ater
follo
win
g co
llect
ion.
S
pilla
ge
of c
hem
ical
s (e
.g. f
uel/d
eter
gen
ts fr
om
leak
ing
cont
aine
rs)
in p
roxi
mity
of t
he s
tand
pipe
ca
n ca
use
cont
amin
atio
n.
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als.
P
ut u
p si
gns
for
appr
opr
iate
car
e an
d us
age
of t
he
com
mun
ity s
tand
pip
e.
Con
duct
ed
uca
tion
pro
gram
s re
gard
ing
the
care
of t
he
com
mun
ity s
tand
pip
e.
RA
IN W
AT
ER
HA
RV
ES
TIN
G
Roo
f pa
int c
onta
ins
chem
ica
l con
tam
inan
ts.
Hea
lth o
r ae
sth
etic
impa
ct o
f che
mic
als.
R
oof p
ain
t mus
t be
sui
tabl
e fo
r po
tabl
e w
ater
, i.e
. it m
ust
not c
onta
in a
ny
lead
. F
olia
ge c
olle
ctio
n ov
er/a
long
gut
ters
and
roo
ftops
. A
esth
etic
imp
act
from
folia
ge.
Dec
ayi
ng d
ebri
s ca
n le
ad
to h
ealth
impa
cts.
F
olia
ge m
ust b
e cl
eare
d re
gula
rly.
D
isin
fect
ion
prio
r to
con
sum
ptio
n.
Bird
/an
imal
dro
ppin
gs c
ont
amin
ate
wat
er.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
G
utte
rs a
nd c
olle
ctio
n ta
nk c
ove
r m
ust b
e w
ell
prot
ecte
d.
Dis
infe
ctio
n pr
ior
to c
onsu
mpt
ion.
F
irst f
lush
of
wat
er c
an e
nter
sto
rage
tank
. H
ealth
or
aest
het
ic im
pact
fro
m w
hat
ever
du
st/d
ebris
th
at m
ight
hav
e co
llect
ed in
the
gutte
rs/p
ipe
. In
stal
l a fi
rst-
flush
div
ersi
on u
nit.
49
H
azar
d
Ris
kC
orr
ect
ive
acti
on
/sH
OU
SE
HO
LD
TR
EA
TM
EN
T
Chl
orin
e un
der
dosi
ng.
Ill
ness
from
ing
estio
n of
har
mfu
l mic
ro-o
rga
nism
s.
Com
mun
ity a
war
enes
s pr
ogr
am
mes
and
de
mon
stra
tions
on
ho
w to
con
duc
t hou
seho
ld d
isin
fect
ion.
C
hlor
ine
over
dos
ing.
E
xpos
ure
to h
arm
ful l
evel
s of
chl
orin
e ca
n ca
use
illne
ss.
Tas
te a
nd o
dour
pro
ble
ms.
C
omm
unity
aw
aren
ess
pro
gra
mm
es a
nd d
em
onst
ratio
ns
on h
ow
to c
ond
uct h
ouse
hold
dis
infe
ctio
n.
Re-
cont
amin
atio
n of
wat
er d
ue
to s
tora
ge in
ope
n co
ntai
ners
that
ma
y b
e ac
cess
ible
to b
irds/
ani
mal
s.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
A
esth
etic
imp
act
on
wat
er.
Sec
ure
cont
ain
ers
with
sea
led
lids
to a
void
co
ntam
inat
ion
from
bird
s/a
nim
als.
R
e-co
ntam
inat
ion
due
to u
nhyg
ieni
c pr
actic
es
wh
en
han
dlin
g/dr
aw
ing
wat
er fr
om th
e st
orag
e co
nta
iner
.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
A
esth
etic
impa
ct t
o w
ater
. C
omm
unity
aw
aren
ess
pro
gra
mm
es a
nd d
em
onst
ratio
ns
on h
ow
to m
ain
tain
hyg
iene
whe
n h
andl
ing/
dra
win
g w
ater
from
the
stor
age
cont
aine
r.
Re-
cont
amin
atio
n du
e to
use
of i
mpr
oper
sto
rage
co
ntai
ner,
e.g
. met
al d
rum
s, a
nd th
e co
ntai
ner
not
bei
ng
mai
nta
ine
d in
a c
lean
co
nditi
on.
Illne
ss fr
om in
ges
tion
of h
arm
ful m
icro
-org
ani
sms.
A
esth
etic
imp
act
on
wat
er.
Avo
id u
sing
met
al d
rum
s/co
nta
iner
s to
col
lect
and
trea
t w
ater
. Use
pla
stic
con
tain
ers
only
. W
ash
stor
age
cont
aine
rs r
egul
arly
; pre
fera
bly
bef
ore
new
wat
er is
bei
ng
dra
wn
befo
re d
isin
fect
ion
.