key responses – water water supply priorities in cholera / awd response

Key responses – Water

Water supply priorities in cholera / AWD response

Session 3.1 WASH Cholera / AWD EP&R training

WASH cholera / AWD EP&R training

2

Learning objectivesBy the end of the session the participants will be able to• explain cholera / AWD transmission risks associated

with most common water sources and possible ways to intervene if sources are identified as contaminated

• describe priorities for provision of water in cholera / AWD response

• list most common field tests used for water quality analysis

• compare appropriateness of most common HHWT methods in cholera / AWD response

2


3

Water sourcesConsider that water might be contaminated withvibrio cholerae where there is contact with:

• People who have cholera (remember they may be asymptomatic)

• Contaminated articles such as buckets, cups and clothes e.g. washing of patients beddings and clothes

• Faecal material e.g. when latrines are close to wells


4

Surface waterWater source Risk of faecal

contamination

Rivers High to very high

Lake High to very high

Rainfall Low to high


5

GroundwaterWater source Risk of faecal

contaminationProtected spring Nil or very low

Closed dug well Low

Open dug Well Medium to high

Borehole Nil or very low


6

Other ways of accessing water

• Vendors• Water trucking• Standpipe


7

Water trucking• Provides immediate supply• Water source and quality can be controlled

Considerations:• Number of trucks to ensure adequate water supply • Cost very high • Requires close monitoring • Offloading to storage facility


8

Importance of proper assessment • Have the different sources of contaminated water been

identified?• Can and have these sources been disinfected?• If not; are there any measures taken to ensure safe

water at household level, or have other water sources been provided?

• If wells are chlorinated is monitoring of residual chlorine levels taking place?

• Is there any system to provide safe water to high risk areas during an outbreak?

• Does population receive at least 15l of water /person /day?

• If chlorine tablets are provided at HH level does the population know how to use them properly?


9

Water Quality vs. Quantity

You see a card in 3 corners of this room

Walk around and decide which would beyour priority for water in cholera / AWDresponse


10

Blocking of transmission of cholera by water interventions

Cholera (Faeces

and vomit)

Fluids (water

sources)

Soil

Hands

Food New Host

Sanitation

Hand washing

Water Quantity

Water Quality


11

Transmission routes and prevention strategies Transmission

routeInfection Prevention strategies

Water-borne Diarrhoeas and dysenteries, including choleraHepatitis A

Improve quality of drinking water usedPrevent casual use of unprotected sourcesImprove sanitation Improve hygiene

Water-washed

Infectious skin and eye diseasesLouse-borne typhus

Increased quantity of water usedImproved accessibility & reliability of supplyImprove hygiene

Water-based SchistosomiasisGuinea worm

Reduce need for contact with infected waterControl snail populationsReduce contamination of surface waters

Water-related insect vector

FilariasisMalariaRiver blindnessYellow fever

Improve surface water management Destroy breeding sites of insects Reduce need to visit breeding sites Use mosquito netting Source Cairncross & Feacham (1999, 2nd edn)

Environmental Health Engineering

in the Tropics


12

Water quantity

Source The Sphere Project (2004)


13

Water Quality

•Physical E.g. turbidity, colour•ChemicalE.g. iron, arsenic•Microbiological and biological

E.g. bacteria, protozoa


14

During a cholera outbreak the most significant parameter to follow up are the bacteriological parameter


15

Sphere key indictors for water quality

• Turbidity (cloudiness index) - less than 5 NTU

• Faecal coliform - 0 FC/ 100 ml

• Residual chlorine (if water is disinfected) – 0.5 mg/l (for piped systems and during outbreaks)


16

Turbidity• Refers to clarity of water i.e. the

greater the amount of total suspended solids the higher the turbidity

• Affects disinfection: high turbidity protects micro-organisms from the action of disinfectants


17

How to test turbidity ?

• Turbidity tube (most common field method)

• Secchi disk

• Electronic devises


18

Microbiological and Biological Water Quality

• E-coli is used as an indicator for faecal contamination

• Testing for E-coli is not always required if the water is going to be treated anyway

• SPHERE key indicator Faecal coliform - 0 FC/ 100 mlRecommendation is to treat (chlorinate) alldrinking water and water used for cooking

during a cholera outbreak


19

How to test microbiological quality in the field

• DelAqua kit• Wagtech

• H2S

• No field tests to detect V.C from water source


20

Use of DelAgua

4 – 6 hours

16hrs incubationON

source Medair Madagascar


21

• An on-site testing method for microbial quality of drinking water

• Faeces contain a high concentration of hydrogen sulphide (H2S) producing bacteria so water contaminated with faeces will react

Hydrogen Sulphide (H2S) tests

Result: Yes / no (presence/ absence)

Turns black when it comes incontact with hydrogensulphide

Eric Fewster, BushProof


Common Household Water Treatment Methods

• Chemical e.g. Chlorination• UV disinfection• Boiling• Filtration

22


0 10 20 30 40 50

% reduction in diarrhoea

Water Supply (quality& quantity)

Water Quality Source

Water QualityHousehold

Sanitation

Hand washing

Water, sanitation, and hygiene interventions to reduce diarrhoea in less developed countries: a systematic review and meta-analysis, Fewtrell et al

(2005)

Data leads to some controversy, partly of the difficulty of splitting impacts of interventions. For example:

* Hand-washing is not possible without a water supply, so ‘hand-washing’ is in fact ‘water supply and hand-washing’

** Water quality at household will also have involved some hygiene promotion when setting up the household water treatment processes

23


Let’s think of appropriateness of different HHWT methods in a cholera / AWD outbreak response

Filtering Boiling

UV disinfection

Chemical

24


Water storage

25


Water storage

26


27

Learning objectivesBy the end of the session the participants will beable to• explain cholera / AWD transmission risks associated

with most common water sources and possible ways to intervene if sources are identified as contaminated

• describe priorities for provision of water in cholera / AWD response

• list most common field tests used for water quality analysis

• compare appropriateness of most common HHWT methods in cholera / AWD response

27

key responses – water water supply priorities in cholera / awd response

Documents

safe water

water sourcesconsider

provision of water

common water sources

cholera awd response

water quality analysis

cholera awd response

water person day