who emergency

7/27/2019 WHO Emergency

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TECHNICAL NOTES ONDRINKING-WATER, SANITATION AND HYGIENE IN EMERGENCIES

1 Cleaning and disinfecting wells

2 Cleaning and disinfecting boreholes

3 Cleaning and disinfecting water storage tanks and tankers

4 Rehabilitating small-scale piped water distribution systems

5 Emergency treatment of drinking-water at the point of use

6 Rehabilitating water treatment works after an emergency

7 Solid waste management in emergencies

8 Disposal of dead bodies in emergency conditions

9 How much water is needed in emergencies

10 Hygiene promotion in emergencies

11 Measuring chlorine levels in water supplies

12 Delivering safe water by tanker

13 Planning for excreta disposal in emergencies

14 Technical options for excreta disposal in emergencies

15 Cleaning wells after seawater flooding

Series Editor: Bob Reed Illustrated by Rod Shaw and Ken Chatterton


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TECHNICAL NOTES ON DRINKING-WATER, SANITATION AND HYGIENE IN EMERGENCIES Updated: July 201

Cleaning and disinfecting wells

1

1.1

TECHNICAL NOTES ON DRINKING-WATER, SANITATION AND HYGIENE IN EMERGENCIES

Flooding, earthquakes, civil unrest and other natural andman-made disasters often cause damage to hand-dug wells.This technical note sets out the actions needed to repair andrehabilitate a hand-dug well so that it can be returned to itsformer condition. The emergency repair and rehabilitationmeasures proposed are temporary and should be followed by

measures for permanent rehabilitation.

Figure 1.1.Steps for cleaning and disinfecting wells

Steps for cleaningand disinfectionFigure 1.1 outlines a four-stepapproach to cleaning and disinfectingwells after natural or man-madedisasters. It is an emergencyapproach designed to rehabilitatewells so that they produce water of asimilar quality to that supplied beforethe disaster (see Box 1.1). TechnicalNote 15 gives further information onwells contaminated by seawater.

Step 1:Inventory of existing wellsThe disaster may have contaminatedor damaged a large number of wells.The first step must be to select whichwells should be repaired first. Theyare the ones that are used most andthat are easiest to repair. The followingactions should help you to make aninformed selection.

Meet with community leaders andask them which wells serve eachsection of the community.

Select the most commonly usedwells as a source for drinking-water that provided a plentifulsupply.

Check there are no obvioussources of contaminationfrom nearby latrines, pondsor surface water. Also maplivestock areas (pig pens,

cattle sheds, chicken coops)as potential sources of contamination by animal waste.

Assess the type and extent of damage to the top of the welland the lining.

Ask the community about theoriginal depth of the well. Usethis to estimate the amount of silt and debris in the well.

Test the pump (if there is one)

to see if it is still working. If not,determine the repairs necessary.

Estimate the resourcesneeded for repairs (personnel,equipment, time and materials).

Box 1.1. Hand-dug wells water qualityWater taken from hand-dug wells is often of poor quality, mainly due tothe poor construction of the above-ground elements and unhygienicmethods of collecting water. The steps described here will not overcomethese problems as they are designed to return the well to its original

condition. Sources of further information on improving and upgradingwells are given on page 1.4.

Step 1:Produce an inventory

of existing wells

Step 2:Clean and rehabilitate

the wells

QUESTIONTest turbidity levels

Are they less than 20NTU?

Step 3:Disinfect the wells

Step 4:Dewater the wells andmonitor chlorine levels

No

Yes


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1.2 TECHNICAL NOTES ON DRINKING-WATER, SANITATION AND HYGIENE IN EMERGENC


Step 2:Rehabilitation andcleaning of wellsThe amount of rehabilitation and

cleaning required will depend on theamount of damage caused by thedisaster. Typically it will include thefollowing steps:

1. Remove and repair/replace thepumping mechanism or liftingdevice.

2. Remove polluted water anddebris from the well using eitherbuckets or pumps. Special caremust be taken when using apump to remove water from wellscontaminated with seawater.(See Technical Note 15 for moredetails.)

3. Repair/reline the well walls toreduce sub-surface contamination.

4. Clean the well lining using a brushand chlorinated water (see Box1.2).

5. Place a 150mm layer of gravel inthe base of the well to protect itfrom disturbance.

6. Seal the top of the well using a

clay sanitary seal (Figure 1.2).7. Construct a drainage apron and

head wall around the well toprevent surface water, insects androdents from entering the well.Provide a cover for the well.

Check turbidity and pHFollowing cleaning and repair, allowthe water level in the well to return toits normal level. Measure the turbidityand pH levels to check whetherchlorination will be effective. Thiscan be done using a simple methoddescribed in Box 1.3. Never chlorinateturbid water because suspendedparticles can protect micro-organisms.Table 1.1 (page 1.4) outlines thereasons why pH and turbidity areimportant and what can be done toensure guideline levels are met. If theturbidity of the well water is greaterthan 20NTU after the cleaning andrehabilitation stage, remove all water

in the well once again and scrub thewell lining with a strong concentrationof bleach in water (Box 1.2).

HSCH and bleach give off chlorine gas which is a serious healthhazard. Try to clean the well lining from outside the well using along-handled brush. If you must enter the well, wear full protectiveclothing and a breathing apparatus and provide a strong air flowinside the well to carry away the chlorine gas.

Figure 1.2.Sealing the top of a well

Box 1.2. Calculating the chlorine dosage for disinfecting a wellusing high strength calcium hypochlorite (HSCH)

Equipment

20 litre bucket HSCH chlorine granules or powder

Method

Calculate the volume of waterin the well using the formula:

Where

V = volume of water in the well (m 3)D = diameter of the well (m)

h = depth of water (m) = 3.142

Fill the bucket with clear water from the well. Add about 300g of HSCH and stir unt il dissolved. For every cubic metre (m 3) of water in the well add 10 litres (half

bucket) of the chlorine solution. Double the quantity of HSCH added if the solution is to be used for

cleaning well linings or aprons.

D

hV

Well

Wellbase

Waterlevel

V = D 2 h4

150mm thick(cast in situ)

Compactedclay

Hardcorefoundation

SealSmoothconcreteslab

1m

2.5m - 3.5m diameter apron

Drainagechannel forwastewater


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1.3TECHNICAL NOTES ON DRINKING-WATER, SANITATION AND HYGIENE IN EMERGENCIES


Allow the well to refill with water andtest the turbidity levels again.

If the water is still turbid, it is probablydue either to:

the failure of the filter pack in thebottom and around the side of thewell; or more likely

to poor protection of the top of the well allowing surface watercontamination.

Neither of these problems can besolved immediately. However, itis probably safe to allow the localcommunity to begin using the well asthe water quality should be at least asgood as it was before the disaster.

Step 3:Disinfection of the wellBefore water is extracted from thewell for consumption, disinfectionis recommended to ensure wellcomponents are hygienically clean.Such disinfection will not provideresidual protection and thereforemeasures to ensure safe collection,handling and storage at home are

highly recommended. This mayinclude use of household watertreatment. Please see Note 5 fordetails.

Chlorine has the advantage of beingwidely available, simple to measureand use, and it dissolves easily inwater. Its disadvantages are that it isa hazardous substance (to be storedand handled with care) and it is noteffective against some pathogens (i.e.it will not remove cryptosporidium ,

a cyst that causes a considerableproportion of diarrhoeal diseaseworldwide).

The chlorine compound mostcommonly used is High StrengthCalcium Hypochlorite (HSCH) inpowder or granule form as it contains60 80% chlorine. Also used issodium hypochlorite in liquid bleachor bleaching powder form. Eachchlorine compound has a differentamount of usable chlorine depending

on the quantity of time the producthas been stored or exposed tothe atmosphere and the way it ismade. Box 1.2 outlines methods for

Box 1.3. Measuring turbidity and the pH level of waterTurbidity is the cloudiness or haziness of a fluid caused by individualparticles. The measurement of turbidity, therefore, is a key test of waterquality. Specialist laboratory or field equipment (a nephelometer) is

required to measure turbidity accurately in Nephelometric Turbidity Units(NTU). If you do not have access to such specialist equipment, then areasonable NTU estimate can be made using locally available materialsas shown below.

Equipment

A clean container with a dark-coloured interior surface such as an oildrum or a dustbin and with a minimum depth of 50cm

A bucket A dull brass or copper coin with an approximate diameter of 2.5cm A long measuring pole or steel tape measure

Method

1. Place the coin in the bottom of the container.

2. Gently add water drawn from the well a little at a time (a). At regularintervals, wait for the surface of the water to calm and check to see if the coin is still visible (b). When it can no longer be seen (c), measurethe depth of the water (d).

If the depth of the water is less than 32cm, then the turbidityis likely to be greater than 20NTU.

If the depth of the water is between 32 and 50cm, then theturbidity is likely to be between 10 and 20NTU.

If the depth of the water is greater than 50cm, then the turbidityis likely to be less than 10NTU.

3. Measure the pH level of the water using pH paper strips (e).

(a)

(b)

(c)

(d) (e)


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1.4

Water, Sanitation,Hygiene and Health Unit

Avenue Appia 201211 Geneva 27Switzerland

Telephone: + 41 22 791 2111Telephone (direct): + 41 22 791 3555/3590Fax (direct): + 41 22 791 4159Email Coordinator: [email protected]: www.who.int/water_sanitation_health

Further information

CDC (Undated) Disinfection of wells following anemergency. Centre for Disease Control andPrevention. USA.http://emergency.cdc.gov/disasters/wellsdisinfect.asp

Collins, S. (2000) Hand dug wells. Series of Manuals onDrinking Water Supply Vol. 5.

Godfrey, S. (2003) Appropriate chlorination techniquesfor wells in Angola, Waterlines, Vol. 21, No. 5, pp 6-8,ITDG Publishing, UK.

OXFAM (Undated) Repairing, cleaning and disinfection of

hand dug wells . http://www.oxfam.org.uk/resources/downloads/emerg_manuals/draft_oxfam_tech_brief_wellcleaning.pdf

SKAT: St Gallen http://www.rwsn.ch/documentation/skatdocumentation.2005-11-14.6529097230/file

WHO (2004) Guidelines for drinking water quality Volume 1. Geneva.http://www.who.int/water_sanitation_health/dwq/guidelines/en/

WHO (2010) How to measure residual chlorine inwater. Technical Note 11

WHO (2010) Cleaning wells after seawater flooding.Technical Note 15


Prepared for WHO by WEDC. Authors: Sam Godfrey and Bob Reed. Series Editor: Bob Reed.Editorial contributions, design and illustrations by Rod ShawLine illustrations courtesy of WEDC / IFRC. Additional graphics by Ken Chatterton.

Water, Engineering and Development Centre Loughborough University Leicestershire LE11 3TU UK T: +44 1509 222885 F: +44 1509 211079 E: [email protected] W: http://wedc.lboro.ac.uk

World Health Organization 2013. All rights reserved. All reasonable precautions have been taken by the World Health Organization to verify the information contained inthis publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation anduse of the material lies with the reader. In no event shall the World Health Organization be liable for damages arising from its use.

Table 1.1.Physico-chemical parameters

Parameter WHO GDWQ* Why? Corrective action

pH 6-8 pH of 6.8-7.2 isrequired to reducelevel of chlorinerequired.

If pH is less than 6 addhydrated lime (calciumhydroxide) to raise pH beforechlorination

Turbidity < 5NTU

(20NTU emergencylimit)

High turbidity requiresmore chlorine tooxidise organic matter

Check the turbidity of thewater entering the wellthrough the walls and base.

Make sure there is nocontamination from thesurface.

*GDWQ: Guidelines for drinking water quality

Do not allow anyone to usethe well during the cleaningprocess.

The water will have a strongconcentration of chlorine thatwill give it a bad taste andsmell and could be dangerous.

calculating appropriate chlorine dosesfor HSCH granule chlorine.

Stir the water in the well thoroughlywith a long pole and then allow thewater to stand for at least 30 minutes.

Further details on chlorination aregiven in Technical Note 11.

Step 4:Dewater the wellFollowing the contact period, removeall water in the well using a pump orbucket. When the well has refilled,wait a further 30 minutes and measurethe chlorine concentration. If theresidual chlorine concentration is less

than 0.5mg/l the well is safe to use.If the concentration is greater than0.5mg/l, remove all the water from thewell again and repeat the process.

Two issues need extra care whendewatering the wells:1) water with high concentration of chlorine should not flow into streamsor wetlands;2) when dewatering on coastal areassalt water intrusion should be avoided(see Technical Note 15).


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TECHNICAL NOTES ON DRINKING-WATER, SANITATION AND HYGIENE IN EMERGENCIES Updated: July 2012.1


Cleaning and disinfecting boreholes

2

Boreholes are resistant to many forms of natural and man-made disasters. Although the components above ground maybe damaged, the narrow opening at the top of the boreholeoften prevents contamination of the water source or damageto the pump components below ground. The main exceptionto this is damage caused by earthquakes, which can be

greater below ground than what can be seen on the surface.This technical note sets out the actions required to repair andrehabilitate a borehole after any disaster.

Figure 2.1.Steps for cleaning and disinfecting boreholes

Driven and drilledboreholesBoreholes fitted to handpumps fallinto two categories pictured overleaf:driven (Figure 2.3) and drilled (Figure 2.4). In general, it is easier

and cheaper to replace damageddriven boreholes than rehabilitatethem. It is usually worth rehabilitatingdrilled boreholes, however, asthey are much more expensive toinstall and require specialist drillingequipment. This note focuses,therefore, on drilled boreholes.

Additional care is needed in therehabilitation of boreholes close tothe sea or coastal swamps becauseof the possibility of seawaterintrusion of the groundwater. Figure2.1 outlines a three-stage approachto rehabilitating damaged drilled

Box 2.1. Boreholes: water qualityIn general, groundwater contains no or low levels of harmful pathogensbut it can be polluted with naturally occurring chemicals. Unfortunately,the quality of water drawn from handpumps fitted to boreholes isvariable. Contamination can be caused by poor sanitary protection at thetop of the borehole. The installation of a sanitary seal and a well aproncan dramatically reduce contamination from the ground surface (Figure

2.2). Sources of further information about improving and upgradingboreholes are given on page 2.4.

Figure 2.2.A sanitary seal and well apron (see Box 2.1)

Step 1:Assess the damage to thehandpump and borehole

Step 2:Repair the borehole

and handpump

Step 3:Disinfect and re-commissionthe borehole and handpump

150mm thick (cast in situ)

Boreholecasing

Compactedclay

Hardcorefoundation

Smoothconcreteslab

2.5m - 3.5m diameter apron

Drainagechannel forwastewater

Sanitary seal

boreholes. It is an emergencyapproach designed to producewater of a similar quality to thatsupplied before the disaster.

Step 1: Assess the damage Meet with community leaders and

ask them which handpumps serveeach section of the community.Obtain any available records of the drilling of the borehole andthe installation of the handpump,particularly concerning thematerials used for lining theborehole, its overall depth andthe depth to the screen.

Select the handpumps thatare most commonly used as asource of drinking-water, provideda plentiful supply before theemergency and are likely to beeasiest to repair.


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Risingmain

Rod

Groundwaterlevel

Boreholecasing

Figure 2.3.Direct action pump on a driven borehole

Figure 2.4.A deep-well pump on a drilled borehole

Box 2.2. Jetting boreholesThe silt at the bottom of the well can often be dislodged by a strong jetof water. Set up a system similar to that shown in Figure 2.6. The water

jet will suspend the silt in the water flow and carry it to the surface asthe water fills the hole. Continue pumping until the water flowing out of the top of the well is clear. From time to time you may have to lower thehose further into the borehole so that it remains close to the silt layer.

Finescreen

Groundwaterlevel

Concrete apron

Plunger

Risingmain

In urban areas, check for possiblecontamination or pollution of the groundwater. Damagedseptic tanks, leaks in industrial

installations and fracturedsewers may all be sourcesof contamination or pollutionseeping into the ground. At theleast suspicion of contaminationor pollution, abandon therehabilitation and seek specialistadvice.

Assess the type and extent of damage to the top of the well.This includes damage to thepump, its connection to the riser

pipe and borehole casing, thesanitary seal and the well apron.

Remove the handpump and riserpipe from the borehole (Figure2.5). Check for damage orblockage with silt.

Check the water level in theborehole. Ask the communitywhat the water depth was beforethe disaster. Earthquakes, inparticular, can cause a major

change in groundwater levels. Asignificant lowering of the waterlevel may require the riser pipe tobe extended or, in the worst case,the abandonment of the borehole.

Check for damage to theborehole casing and screen.Examine the pump riser pipe as

Figure 2.5. Removing the riser pipe


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it is extracted. If it is difficultto remove or has obvioussigns of damage it is likelythat the lining has beendamaged. Borehole liningrepair is difficult. For immediateimprovement of the situation,stop the assessment andinvestigate alternative sources.

Estimate the amount of silt anddebris in the borehole. Examinethe bottom of the pump riserpipe to see if it is covered insilt. A clean pipe indicates thatany silt that may have enteredthe borehole is lying below thebottom of the riser pipe.

Dismantle the pump and riserpipe to check for damage andworn parts.

Estimate resources needed forrepairs (personnel, equipment,time and materials).

Figure 2.7. Checking the water for silt

the pump is working, thewater produced is clear of silt(Figure 2.7) and the flow rate

is acceptable. If the water stillcontains silt, remove the pumpand flush out the borehole again.If, after two flushes, the boreholeis still producing silty water, theborehole screen is probablydamaged and no further attemptat repair should be made.

5. Repair the clay sanitary sealat the top of the borehole andthe drainage apron around theborehole to prevent surface

contamination of the groundwater(Figure 2.2, page 2.1).

Step 3: Disinfect andrecommission the boreholeand handpumpFollowing rehabilitation, the boreholeand all components must bedisinfected to ensure a clean watersupply. Operate the handpumpfor about an hour to remove any

groundwater contamination causedby the disaster or the jetting process.

The most common method of disinfection is chlorination. Thechlorine compound most commonlyused is high-strength calciumhypochlorite (HSCH) in powder orgranular form which contains 60to 80% available chlorine. Sodiumhypochlorite in liquid bleach formis also used but this only containsabout 5% available chlorine.

Box 2.3, page 2.4 outlines a methodfor disinfecting a borehole usingHSCH.

Step 2: Repair the boreholeand handpump1. Flush the sediment from the

borehole. There are a numberof ways of doing this but thesimplest method is jetting(see Box 2.2, page 2.2). Othermethods are possible but requirespecialist skills and equipment.

2. Check the top of the boreholecasing for damage. If it is bentor twisted it will not be possibleto install the pump correctly.

You may have to cut away thedamaged portion of the casingand weld a new piece into place.

3. Repair any damage to thepump and riser pipe. Take theopportunity to replace wornparts.

4. Re-assemble the pumpand reinstall the boreholecomponents. Check that

5000 litre water tanker

Water hose

Water table

3mCasing

Water pumpWater overflowingto waste

High pressure water hose

Screen

Figure 2.6. Flushing out a borehole by jetting


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Further information

Godfrey, S. and Ball, P. (2003) Making Boreholes Work:Rehabilitation strategies from Angola, 29th WEDCConference Proceedings, WEDC, Loughborough,UK.

Ball, P. (1999) Drilled Wells , SKAT Publications,Switzerland.

EPA (2006) Private Drinking Water Wells: What to do after the flood, http://water.epa.gov/drink/info/well/whatdo.cfm

Agriculture and Agri-food Canada (Undated) Water Well Disinfection Using the Simple Chlorine Method , WaterStewardship Information Series. British Colombia.http://www.env.gov.bc.ca/wsd/plan_protect_sustain/groundwater/wells/factsheets/PFRA_simple_chlorification.pdf

Skinner, B. H. (2003) Small-scale Water Supply: A Review of Technologies. Practical Action Publishing, Rugby, UK


Water, Engineering and Development Centre Loughborough University Leicestershire LE11 3TU UKT: +44 1509 222885 F: +44 1509 211079 E: [email protected] W: http://wedc.lboro.ac.uk

2.4

Water, Sanitation,Hygiene and Health UnitAvenue Appia 201211 Geneva 27Switzerland




DANGER: HSCH and bleachgive off chlorine gas which is aserious health hazard. Alwaysadd chlorine compounds towater rather than water tochlorine. Work in an area with agood flow of air to take away thechlorine fumes. Wear protectiveclothes, especially face and eyemasks and gloves. Do not allowanyone to use the handpumpduring the cleaning process.

Pour the chlorine liquid into theborehole (you may have to removepart of the pump to do this). Replacethe pump and operate it until chlorinecan be smelled in the outflow.

Allow the water to stand in theborehole for 12 to 24 hours andthen operate the pump until all thechlorinated liquid has been removed.If you have a chlorine test kit you cancheck the chlorine concentration inthe water.

Alternatively, pump the water until itno longer smells of chlorine. TechnicalNote 11 gives more details on testingfor chlorine.Disinfection will not provide residualprotection and therefore measuresto ensure safe collection, handlingand storage at home are highlyrecommended. This may include useof household water treatment. Pleasesee Note 5 for details.

Box 2.3. Calculating the chlorine dosage for disinfecting a boreholeusing high-strength calcium hypochlorite (HSCH)

Equipment

20 litre bucket HSCH chlorine granules or powder

Method

Calculate the volume of waterin the borehole using the formula:

Where

V = volume of water in the borehole (m 3)D = diameter of the borehole (m)h = depth of water (m) = 3.142

Multiply the answer by 1000 to convert the answer to litres Divide the volume of water (in litres) in the borehole by the volume

of the bucket to establish how many buckets of disinfectant will beneeded to replace the total volume of the water in the borehole.

Fill the bucket with clear water Add 1g of HSCH powder and stir until dissolved (0.5g for every10 litres

in the bucket) Pour the disinfectant into the borehole

Make up sufficient buckets of disinfectant to replace the total volumeof water in the borehole.

D

hV

Borehole

Boreholebase

Waterlevel

V = D 2 h4


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Cleaning and disinfecting water storagetanks and tankers

3

In an emergency situation, it is often necessary to quicklyprovide a basic water supply for the affected population. Thismay be because the normal systems of supply have beendamaged or destroyed. The most common, immediate solutionis to hire vehicles and tanks that have been used for otherpurposes or to retrieve collapsible tanks from an emergency

store. In either case, they must be cleaned and disinfectedbefore being used. This technical note outlines a four-stepapproach to cleaning and disinfecting water tanks and tankers.

Figure 3.1.

Steps for cleaning and disinfecting watertanks and tankers

Procedural stepsIn the case of an emergency, it isan accptable practice to disinfecttanks that are polluted or not inuse so that drinking-water can betransported and stored safely. Figure

3.1 presents the four-step approachto cleaning and disinfecting watertanks.

Note: Large quantities of cleanwater will be required to cleanand treat tanks before they canbe used to transport or storewater.

Step 1:Select the tanks to useTanks should be selected based onthree considerations: normal use;ease of cleaning and water storagehygiene.

Selected tanks should only havebeen used for holding food-gradeliquids, for example, milk, cookingoils, fruit juices, wines and spiritsor vinegar. Tanks previously usedfor holding non food-grade liquids

such as fuel and sewage should not be used. Tanks that previously heldwater but have been out of use for

some time must also be cleanedand disinfected as describedbelow under Steps 2 and 3.

Tanks must be easy to clean. Thismeans they must be accessiblefor cleaning and have no sharpcorners that may hold dirt andso prevent the removal of fooddeposits.

Water will only remain clean if stored safely. Tanks must thereforebe covered and fitted with anaccess point with a lockable lid.

Step 2: CleaningEmpty the tank Open the outlet valve or tap anddrain out any remaining liquid.Collect the liquids so that they canbe safely disposed of (see Step 4).

In the case of tankers, outlet valvesare usually located at the backso parking it on a slope will helpto ensure that all the liquid canbe discharged (see Figure 3.2overleaf).

Permanent storage tanks areusually fitted with a washout valvethat draws liquid from the base.Use this, rather than the normaloutlet valve, for emptying.

Step 4:Safely dispose of

liquid waste

Step 1:Select the tanks and

tankers to use

Step 2:Clean the tanks

and tankers

Step 3:Disinfect the tanks

and tankers

Scrub the internal surfaces ofthe tank Use a mixture of detergent and hotwater (household laundry soappowder will do) to scrub and cleanall internal surfaces of the tank. Thiscan be done with a stiff brush ora high pressure jet. Attaching the

brush to a long pole may make itpossible to clean the tank withoutentering it (Figure 3.3).


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Cleaning and disinfecting water storage tanks and tankers

Figure 3.2.Discharging liquids from tanks and tankers

Take special care to clean cornersand joints so that no small amountsof the original liquid remain. Evenminute amounts of some liquidscan give the water a bad taste andpeople will refuse to drink it.

Leave the outlet valve open whilecleaning and collect the liquid forsafe disposal.

Wash and flush the tank This is most easily done with a highpressure hose pipe or water jet butif they are not available the tank canbe filled with (preferably hot) waterand left to stand for a few hours.Drain all the water from the tank andcollect for safe disposal as before.

Continue flushing the tank until thereare no longer traces of detergent inthe water.

Step 3: DisinfectionThe most common way of disinfecting a water tank is bychlorination. Chlorine is deliveredin a variety of ways but the most

common is high-strength calciumhypochlorite (HSCH), which, whenmixed with water, liberates 60 to80% of its volume as chlorine.

Calculate the volume ofthe tank The amount of chlorine needed todisinfect the water tank will dependon its volume. Box 3.1 describeshow to calculate the volume of common tank shapes.

Tanker parked onslope or rampto let water out

2-wheeled donkeycart on end tolet water out

Normal storage tank outlet

Wash-out pipe

Wash-out valve

Important note:Tank cleaning should takeplace in open areas away fromhouses to avoid possible healthproblems resulting from the

disposal of the wastewater.

Clean hosesThe hoses, pumps and pipes usedfor filling and emptying the tankmust also be cleaned. Flush amixture of hot water and detergentthrough the pipes and pump toremove deposits and other wastematerial.

Once cleaned, flush the system withclean water to remove the detergent.

Figure 3.3.Cleaning the inside of a tank with a brush


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Box 3.1. Calculating the volume of a tank Storage tanks are commonly one of three shapes, rectangular,cylindrical or oval. If the tank is another shape, approximate its volumeby using the formula that most nearly fits the shape.

Rectangular ground storage tanks

Volume (litres) = L x W x D x 1000

WhereD = depth of the tank (m)W = width of the tank (m)L = length of the tank (m)

Cylindrical ground storage tanks

Volume (litres) x 1000

WhereD = diameter of the tank (m)L = length of tank (m)

= 3.142

Oval water tankers

Volume (litres) = ( x (D + W) 2 /16) x L x 1000

WhereD = depth of the tank (m)W = width of the tank (m)L = length of the tank (m)

= 3.142

Add the disinfectantFill the tank a quarter full with cleanwater. Sprinkle 80 grams of granularHSCH into the tank for every 1000litres total capacity of the tank. Fill

the tank completely with clean water,close the lid and leave to stand for24 hours.

If the tank is required for useurgently, double the quantity of chlorine added to the tank. This willreduce the time of disinfection from24 to 8 hours.

Disinfecting the hosesand pumpIf the tank is fitted with a pump,connect the hoses so that water isdrawn from and returned to the tank(Figure 3.4).

With the tank full of water anddisinfectant, start the pump so thatthe mixture passes through thehoses and pump. Run the pumpfor about an hour. Repeat thisprocedure with the tank full of cleanwater.

If no pump is fitted, use some of thedisinfectant from the tank and gentlyfill the hoses to full capacity. You willhave to block one end of the hoseand fill it from the other end. Allow tostand for 24 hours.

Empty out the disinfectant andconnect the hoses to the tank outletso that when the clean water in thetank is discharged it passes throughthe hoses. The hoses are now readyfor use.

Prepare for useCompletely empty the tank andcarefully dispose of the disinfectingwater as it will contain a highconcentration of chlorine. Fill thetank with drinking-water, allow tostand for about 30 minutes thenempty the tank again. The tank isnow ready for use.

Figure 3.4. (Right) Recirculating chlorinatedwater to disinfect the pump and hoses

L

D

L

D

W

L

W D

= D 2 L4


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Further information

Davis, J. and Lambert, R. (2002) Engineering and Emergencies: A practical guide to fieldworkers, 2ndEdition, Practical Action Publishing, UK.

Massachusetts Department of Environmental Protection(Undated) Procedures for Emergency Tank Truck Bulk Water Haulage. http://www.mass.gov/dep/water/drinking/blkwfct.doc

Louisiana Department of Health and Hospitals (Undated)Instructions for Emergency Tank Truck Bulk Water Hauling in Louisiana. http://www.dhh.louisiana.gov/offices/publications/pubs-204/Bulk%20Water%20Hauling%20Instructions.pdf




3.4




Gaining access and workinginside a water tank can be

difficult and dangerous. There isoften only a small access hatchon the top of the tanker throughwhich to climb in and out.Cleaners should be aware thatsome liquid held in tanks cangive off hazardous gases whichmay remain even when theliquid has been removed. Theliquids may also pose physicalhazards such as slipperysurfaces. Corrosive liquids cancause burns.

Always blow fresh air into thetank for a period before allowinga person to enter. The cleanershould wear protective clothing,including gloves, boots, a hatand glasses (Figure 3.5). Makesure someone remains outsidethe tank, next to the accesshatch all the time in case thecleaner has an accident. Theavailability of gas masks and

portable ventilators would be anadvantage.Figure 3.5.Wearing protective clothing for cleaning

Step 4: Safely dispose ofliquid wasteCare must be taken when disposingof all liquids used for cleaning anddisinfecting the tanks. Suddendischarge of water will causelocalized erosion or flooding. Makesure the water follows a channel toits final disposal point.

Box 3.2. Additional health andsafety issues

Liquid waste should not bedisposed of in rivers and pondsas the organic materials and highchlorine levels may kill fish and plantlife. Wastewater should be disposedof to a sewer network, carried intankers to a sewage treatment

plant or placed in a septic tankthat overflows into an undergroundsoakage system.

Figure 3.6.Delivering safe water from a water tanker


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TECHNICAL NOTES ON DRINKING-WATER, SANITATION AND HYGIENE IN EMERGENCIES Updated: 2014.1


Rehabilitating small-scalepiped water distribution systems

4

The damage caused by natural disasters to networks forpiped drinking-water distribution can be widespread andextensive. It can range from minor breaks to complete lossof whole sections of the system. A systematic survey of theentire network is the only way of identifying the true extentof the damage. This may not be possible in an emergency

where the priority is to re-instate a basic level of supply. Thistechnical note examines these priorities and the process ofrehabilitating small-scale piped water distribution systems.

Figure 4.1.Steps for rehabilitating a small-scale pipedwater distribution system

Step 4:Isolate damaged sections

of the network

Step 1:Assess the extent of thedamage to the network

Step 2:Keep consumers informed

about the situation

Step 3:Provide an alternative water

supply where necessary

Step 5:Repair breakages

to the network

Step 6:Test, clean and disinfect

the repaired pipe sections

Steps of rehabilitationThe first priority is to repair majorbreakages in the system. This willallow the re-instatement of a supplybut with the knowledge that muchof the water entering the networkwill be lost through breaks not yetfixed. Once the emergency supply isin place, work can begin to identifyand repair smaller breaks. Figure 4.1shows the steps for repairing majorbreaks in pipe networks.

Step 1: Assess the extentof the damageIdentify local staff with knowledgeof the distribution system as theirinvolvement in the rehabilitation will

make the job much easier. Obtain anyavailable drawings of the distributionnetwork layout, including informationabout the size of pipes and positionsof fittings such as valves andwashouts. At the very least, obtaina plan of the community showingmain roads and important buildings.For many parts of the world, suitablemaps can be freely downloaded fromthe Internet. Inspect the whole of thepiped network and mark on the plansthe positions of all major damage,its nature (for instance whether it isa broken valve, a fractured pipe, alost pipe section) as well as the type

of pipe affected (see Figure 4.3). Focuson visible damage. It is likely that therewill be damage underground but thiscan be dealt with later. Check the localstores to see if there are enough sparepipes and fittings of the correct size, andmaterials and equipment to begin the

repairs. If not, order these immediately.

Step 2: Keep consumersinformedIt is important to keep water usersinformed about what is happeningand how you propose to deal withthe situation (Figure 4.2). Let themknow which sections of the networkare affected, what you intend to doand when, and what they should doto protect their health and safety.Communication is an on-goingresponsibility and regular updatesshould be provided.

Figure 4.2. Keep the consumers informed


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Rehabilitating small-scale piped water distribution systems

Step 3: Provide analternative water supplyIf damage to the network is major,and repairs will take more than a fewhours, an alternative supply mustbe provided. This could take theform of bottled drinking water, waterdelivered directly by tanker (Figure4.5), and water tankers delivering totemporary storage tanks. Combinethis with advice about local sourcesof water (such as springs or wells)which might be used for other, non-drinking purposes.

Provide information about simplehousehold water treatment optionsand the availability of chemicals todisinfect local sources.

In all cases, water users must beinformed about what is being doneand how they can use the temporarysystem effectively.

Step 4: Isolate damagedsections of the networkThe affected area or areas should

be isolated from the rest of thedistribution network. This will reducewater wastage and allow a supplyto continue to unaffected areas.Isolation is usually undertakenusing control valves. If they are notavailable, or cannot be traced, newvalves will have to be installed.

Step 5: Repair breakagesStart at, or near, a source of supply and work outwards into

the distribution system. Repair thepipeline in a stepped manner. Forexample, referring to Figure 4.4,

Figure 4.3.Map of a piped distribution network with a record of damage

Figure 4.4.Repair the pipeline in a planned and stepped manner

Figure 4.5.Provide an alternative water supply

Service reservoir(if needed)

Branchpipeline

Mainpipeline

Branch pipeline

Service pipe

Main pipeline(transmission main

Source orreservoir tank

Branchpipeline

SV2SV1

FH1SV3

WO1 SV5

SV4

SC1

SC2

SV6

B1 B2

KEYSV Stop valveB BreakageWO Wash-out valve

SC Boundary stop cockFH Fire hydrant

End of linewashed away.

Section badlydamaged with

junction fittingslost.

Whole sectionwashed away.

Multiple breaksin section.


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start with the section between thesource and the service reservoir.

Follow this repair by rehabilitatingthe main pipeline from SV1 to SV5,making sure to close valves SV2, 3and 4 and any service connectionsfirst. Select a pipeline section thatcan be easily isolated by existingstop valves, of say 500 to 1000mapart.

Arrange to install washout valves(such as WO1), and fire hydrants(such as FH1) if none can be tracedin the selected section.

Before starting any repair work:

Locate other undergroundutilities at work in the area, andliaise with their maintenancedepartments, if necessary.

Route traffic away from the workarea.

Excavate and expose the brokensections of the pipelines. Protect therepair crew from trench collapse.This is normally not a problemwith small diameter pipes but if theground is very loose protect them byshoring the work area as illustratedin Figure 4.6.

Use simple methods of repair thatwill take the shortest time to restoreservices.

Examples of simple methods:

The damaged section may bereplaced by use of repair pipeclamps, as shown in Figure 4.7.

Repair of cracks and breaks insteel pipes by welding.

If there are multiple breaks, itmay be quicker and easier toreplace the whole section with anew pipe. A temporary pipe runabove ground is satisfactory foran emergency supply.

Replace pipe support structuressuch as concrete anchorage andthrust blocks, if necessary.

Backfill around the pipe withselected material such as dry sandor washed stone (Figure 4.8). Theremainder of the excavation can befilled with the excavated soil. Leavethe pipe joints exposed so thatthey can be observed during waterpressure testing.

Step 6: Test, clean anddisinfect the repaired pipesectionsPipe testing

Partly open the upstream isolationvalve and the downstream washoutto fill the repaired pipeline sectionwith water.

Once full, increase the pressurein the pipe by at least 50%. This isachieved by:

closing the upstream valve anddownstream washout;

connecting a water pump

between a water tanker and theupstream fire hydrant; and switching on the water pump and

maintaining the high pressure forat least 4 hours.

Observe the pipe joints for leaksand repair if necessary. Check theamount of water being pumpedfrom the tanker into the pipeline andcompare with the figures given inTable 4.1. If the leakage is greaterthan recommended, it indicatesother major leaks in the section.Sources of further information aboutways of searching for hidden leaksare provided on page 4.4.

CleaningConnect a full tanker of clean water,via a water pump, to the upstreamfire hydrant or washout for thesection of pipe you are workingon. Confirm the pump can deliverthe quantity of water and pressurerequired to flush and clean the pipe.

Figure 4.6.Shoring the work area

Tight sheathing

Walers

Struts

Figure 4.7.A pipe clamp

Pipediameter(mm)

Normalallowableleakage(litres/ day/1000m)

Emergencyallowableleakage (litres/ day/1000m)

5075

100150

165250

330500

330500

6601000

Table 4.1.Allowable leakage from pipes

Source: California State University (1994)Figure 4.8.Backfilling


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Further information

California State University, Sacramento School of Engineering (1994), Water Distribution SystemOperation and Maintenance , 3rd ed., California StateUniversity, Sacramento Foundation, USA.

Bhardwaj V (Undated) Technical Brief Repairing LineBreaks. National Drinking Water Clearing House.http://www.nesc.wvu.edu/ndwc/articles/OT/SP04/TechBrief_LineBreaks.pdf

AWWA (1999) Water Distribution Operator Training Manual. American Water Works Association, 2nd ed. Denver,Colorado. USA

Male, J. Walski, T.M. (1991) Water Distribution Systems: A Troubleshooting Manual. 2nd ed. Chelsea, MI LewisPublishers, Inc, USA

IWES (1982) Water Practice Manual 3: Water Supply and Sanitation in Developing Countries, IWES London


Prepared for WHO by WEDC. Authors: Sam Kayaga and Bob Reed. Series Editor: Bob Reed.Editorial contributions, design and illustrations by Rod ShawLine illustrations courtesy of WEDC / IFRC. Additional graphics by Ken Chatterton.


4.4




Table 4.2 gives guidelines foradequate velocities and flow.

Open the hydrant connected to thepump and tanker. Turn on the pump.Gradually open the downstreamwashout valve until the flow ratereaches the required level. Pumpuntil the water coming out of thewashout is completely clean butnot less than the time suggested inTable 4.2.

Direct flushing water away fromtraffic, pedestrians and private plots.

Avoid erosion damage to streets,lawns and yards by use of tarpaulinsand lead-off discharge devices.

Avoid flooding which can causetraffic congestion. When the watercoming out of the pipe is clean,slowly close the washout valvebefore turning off the water pump.

DisinfectionCalculate the volume of waterrequired to fill the section of pipeusing Table 4.3. Acquire tankersof volume equal to, or higher than,

the calculated volume of the pipe. As the tankers are being filledwith clean water add 80g of HighStrength Calcium Hypochlorite(HSCH) granules for every 1000

litres. (See Technical Note 3 forfurther information about thechlorination of tankers.)

Connect the water tanker to the up

stream fire hydrant. Open the valvesbetween the tanker and the pipe.Gradually open the down streamwashout so that the chlorinatedwater replaces the clean water in thepipe (it may be necessary to pumpwater into the pipe).

Continue feeding water into thepipeline until chlorine can bestrongly smelt in the water comingout of the washout. Close the

washout valve but leave the inletvalves open so that chlorinatedwater can still enter to replaceleakage. Leave the pipeline for 24hours.

Disconnect the water tanker andopen the upstream isolating valve.

Gradually open the downstreamwashout and monitor the water

coming out until it no longer smellsstrongly of chlorine.

The pipe can then be returned toservice.

Pipediameter(mm)

Velocity required(m/s)

Flow required(litres/sec)

Minimum flushingtime for a 1000m pipe(mins)

5075100150

1.31.61.82.2

2.77.215.041.0

770625555455

Table 4.2.Velocity and flow required for flushing

Source: Adapted from Institution of Water Engineers and Scientists (1984)

Pipediameter (mm)

Approximate watervolume per 1000m of pipe(litres)

5075100150

1,9604,4207,85017,670

Table 4.3.Quantity of water required to fillpipes of different diameters


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Emergency treatment of drinking-waterat the point of use

5

Normally, drinking water supplies need to be treated duringand after an emergency to make them safe and acceptable tothe user. Treatment at the point of use is generally quicker andless expensive to implement than a centralized system, but itcan be more difficult to manage. Only water used for drinkingand preparing food needs to be treated. Nevertheless, this still

amounts to about five litres per person per day. This technicalnote describes some of the most common and simpletreatment options suitable for use during an emergency.

Pre-treatmentThere are a wide variety of technologies for treating water at thepoint of use. The methods describedbelow will remove physical andmicrobiological pollution, but notchemical contamination.

Water treatment can make drinking-water that is unsafe at the sourceor drinking-water that becomescontaminated during handling andstorage safer. There are a number of different methods and the preferredmethod or combination of methodsdepends on a number of factorssuch as source water quality,including turbidity or number of suspended particles in the water,availability of different methods andsupply chains, user preferences andcost.

Aeration Aeration brings water into closecontact with air which increases theoxygen content of the water.

This will: remove volatile substances

such as hydrogen sulphide andmethane which affect taste andodour;

reduce the carbon dioxidecontent of the water; and

oxidize dissolved minerals suchas iron and manganese sothat they can be removed bysedimentation and filtration.

Water can be aerated in a numberof ways. One simple method forhouseholders is to rapidly shake acontainer part-full of water for aboutfive minutes (Figure 5.1), leave itstanding for a further 30 minutes toallow any suspended particles tosettle.

Figure 5.1.Aeration by vigorously shaking water

Storage and settlementIf water is turbid it can be allowedto stand and settle to removelarger particles. However, even aftersettling, water should be treatedwith a proven method to ensure itis safe to drink. Additionally, thesuspended solids and some of the

pathogens will settle to the bottomof the container, removing furtherrisk. Storage for two days reducescontamination further still, and also

reduces the number of organismswhich act as intermediate hostsfor diseases such as Guinea worminfection (dracunculiasis) .

Filtration A fil ter removes contamination byphysically blocking particles whileletting the water pass through.

Membrane filtersMembrane filters operate usingsimilar removal mechanisms asother filters and can be highlyefficacious in removing even smallerorganisms such as viruses. Themanufacturers instructions on useshould be adhered to as often suchfilters require regular cleaning.

Sand filtersHousehold filters may be assembledinside clay, metal or plasticcontainers. The vessels are filledwith layers of sand and gravel andpipework arranged to force thewater to flow upwards or downwardsthrough the filter. Figure 5.4 shows asimple upward rapid flow filter.

Ceramic filtersWater passes slowly through aceramic or candle filter (Figure5.3). In this process, suspendedparticles are mechanically filteredfrom the water. Some filters, for


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Emergency treatment of drinking-water at the point of use

example, are impregnated with silverwhich acts as a disinfectant andkills bacteria, removing the need forboiling the water after filtration.

Ceramic filters can be manufacturedlocally, but are also mass-produced.They have a long storage life so canbe stored in preparation for futureemergencies.

Cover

Inlet

Outlet

3 0 0 m m

Water

Coarsesand

Perforatedmetal plateRocks

Drainstopper

Figure 5.4. A simple upward, rapid flow filter

Figure 5.3. Ceramic or candle filters

(a) Manufactured unit (b) Candle with jars

Impurities retained by the surfaceof the candle need to be brushedoff under running water at regularintervals.

DisinfectionDisinfection destroys all harmfulorganisms present in the water,making it safe to drink.

BoilingBoiling is a very effective method of disinfecting water, but it is energyconsuming. The water should bebrought to a rolling boil. Apart fromthe high cost of the energy involvedin boiling, the other disadvantage

is the change in taste of the water.This can be improved by aeration,by vigorously shaking the water in asealed container after it has cooled.

Chemical disinfectionMany chemicals can disinfect waterbut the most commonly-used ischlorine. With appropriate dosing,chlorine will kill most viruses andbacteria, but some species of protozoa (notably cryptosporidium )

are resistant to chlorine. There areseveral different sources of chlorinefor home use; in liquid, powderand tablet form. They vary in sizeand strength (i.e. in how muchchlorine they contain) so differentquantities are required dependingon the formulation. Always follow themanufacturers instructions for use.To prevent misuse, clear instructionsmust be given to all users (seeFigure 5.5).

Chlorine compounds should notbe given out to users outside ofthe container they are suppliedin by the manufacturer. Peoplecannot tell how much of theproduct to use or how to use itsimply by looking at it!

Solar disinfection (SODIS)Ultra-violet rays from the sun willdestroy harmful organisms presentin the water.

Fill transparent one- or two-litreplastic containers with clear water

and expose them to direct sunlight.The length of time needed forinactivation of pathogens will varydepending on the transparency of the container, intensity of sunlight,and clarity of the water. In areasnear the equator, on a sunny day 24hours is likely sufficient or 48 hoursfor a cloudy day. Devices are nowavailable which can be attached tothe bottles to indicate when sufficienttemperatures have been reached forinactivation. (Figure 5.6),

Cool the water and shake vigorouslybefore use.

Combined treatment systems A few large companies havedeveloped compounds that bothremove suspended particles anddisinfect the water. One suchcompound contains a chemical thathelps suspended particles join to

make larger, heavier ones that willsettle to the bottom of the container.It also contains chlorine thatdisinfects the water after settlementhas occurred.

Training on use of technologySuccessful emergency programsprovide and effective treatmentmethod with which the affectedpopulation is already familiar, andadequately invest in developing

culturally appropriate materials andapproaches to support correct use of the selected method(s).

(c) Using candle with siphon

(d) Porous jar


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Figure 5.6. Solar disinfection (SODIS) Figure 5.7. Tap fitted to a water bucket

Figure 5.5. How to treat water with chlorine tablets (adapted from IFRC, Geneva) * The required number of chlorine tablets depends on sof container and % of active chlorine in tablets. Before dosing consult with manufacturers instructions.

Looking after clean waterThere is no point in treating waterif it becomes contaminated againafterwards. The storage and use of treated water is just as important asthe treatment process.

Water storageWater should be stored in clean,covered containers and kept in a cool

dark place. Wide-necked containerssuch as a bucket fitted with a tightfitting lid are the best as they are easyto clean between uses.

Is your water clear?

Wash your hands withwater and soap or ash

Put 1 tabletin a container

x 1

30

Close containerwait 30 minutes

Is your water dirty?Put 2 tabletsin a container

x 2

30

Close containerwait 30 minutes

Water is nowready to drink

Filter the waterthrough cloth

Contamination can also occur asthe water is taken out of the storagecontainer. Hands and utensils maycome into contact with the water soit is important to encourage users towash their hands with soap beforehandling drinking water; and to fit atap to the storage container so thatwater can be poured directly into acup or bowl (Figure 5.7).

Hygiene promotionThe benefit of providing safedrinking-water will be lost if usersdo not know how they will benefit.

Changing unhygienic behaviour is just as important as the provisionof clean water. Emergencies canprovide a good opportunity tointroduce new hygienic practices.

As users settle into a newenvironment, they are more likelyto accept changes to their normalbehaviour. For water supply andsanitation, the most importantpractice to change relates tohandwashing. Dont assumeeveryone knows how to wash theirhands properly. Show them.


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Further information

CEHA (2004) Guide to the promotion of drinking-water disinfection in emergencies http://www.emro.who.int/ceha/pdf/DrinkingWater_Disinfection_En.pdf

Centers for Disease Control and Prevention. Fact sheetson HWTS methods. http://www.cdc.gov/safewater/household-water.html

IFRC (2008) Household water treatment and safe storage in emergencies http://www.ifrc.org/Docs/pubs/disasters/resources/responding-

disasters/142100-hwt-en.pdf Shaw, Rod (ed.) (1999) Running Water: More technical

briefs on health, water and sanitation , ITDG, UK.

Smet, J. & Wijk, C. van (eds) (2002) Small community water supplies Chapter 19. Disinfection, IRC TechnicalPaper 40, IRC: Delft http://www.irc.nl/content/download/128541/351015/file/TP40_19%20Disinfection.pdf

SODIS (Undated) How do I use SODIS? http://www.sodis.ch/Text2002/T-Howdoesitwork.htm

United States Agency for International Development.Environmental helth topics: Household water t reatment.http://www.ehproject.org/eh/eh_topics.html

WHO/UNICEF International Network on Household WaterTreatment and Safe Storage. http://www.who.int/household_water/resources/en/


Prepared for WHO by WEDC. Authors: Sam Kayaga and Bob Reed. Series Editor: Bob Reed.Editorial contributions, design and illustrations by Rod ShawLine illustrations courtesy of WEDC / IFRC. Additional graphics by Ken Chatterton.


5.4




Box 5.1. HandwashingEveryone should wash their hands with soapand water:1) after defecation;2) before preparing food;3) before eating food, breastfeeding or

feeding children; and4) after cleaning a childs feces.

1a 1bor

2 3 4 5

6 7 8 9


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Rehabilitating water treatment worksafter an emergency

6

In urban areas, the population may be entirely reliant on thepublic water supply system for their drinking-water. Modernwater treatment works rely on the inputs of skilled operatorsas well as supplies of chemicals, electricity and machinery.A disaster can cause extensive damage to the works leadingto a reduced or even a total loss of output. This technical

note identifies the first steps to take towards rehabilitatinga water treatment works after an emergency. Details of therehabilitation of smaller systems are given in Technical Note 4.

Figure 6.1. Modern water treatment works rely on the inputs of skilled operators as well assupplies of chemicals, electricity and machinery that functions reliably

Water source

Drinkingwater

Power

Water treatmentworks

Staff Chemicals

Steps for rehabilitationIn an emergency, the primary goalof rehabilitating a water treatmentworks is to maximize the quantityof water produced. This is followedby the gradual, step-by-stepimprovement in water quality.Most water treatment works areconnected to a piped distributionsystem. This, too, needs to berehabilitated if the treated water is toreach the consumer. Details of therehabilitation of distribution systemsare given in Technical Note 4.

Assess the situationIdentify key workersIdentify local water treatmentoperators who understandthe system. They can provideknowledge of the works and thesources of supply. Often, however,operators do not fully understandthe treatment process, so try toidentify professional engineers,scientists and managers who do.Note that you may have to payoperators and managers if theemergency has interrupted theirsalary payments.

Understand the processIn order to rehabilitate the watertreatment plant it is important to


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Rehabilitating water treatment works after an emergency

understand how it works. Individualplants will vary in design, but most arebased on a sequence of processesthat fit together to improve the qualityof water in incremental steps. Figure6.3 shows the principal processes.Not all processes shown will operatein every case. In some cases theorder in which they take place willdiffer.

Assess the condition of the plantThe condition of each plantcomponent will need to be assessed.Identify which components areworking, which could be repairedand which will have to be replaced.Repair and renovation is generallyquicker than replacement, particularlyif skilled workers are available locally.Be aware that damaged componentsmay not necessarily be related to thedisaster. Chronic underfunding andlack of skilled workers is a commonproblem in the water industry, sotreatment plants frequently do notfunction correctly, not only duringemergencies.

Decide what to do firstThe first requirement is to get waterinto the distribution system quickly.Water quantity (rather than quality)provides the main health and socialbenefits during an emergency.Treatment, therefore, can be limited inthe first instance, but ensure that thewater is free of gross contaminantsthat may block or damage pipes andpumps.

Preventing pollutionThe first step in improving waterquality is to reduce the need fortreatment by minimizing the levelof pollution at source. Providingenvironmental sanitation services(such as the management anddisposal of excreta, solid wasteand rainwater), controlling erosion,reducing agricultural pollution andrestricting direct public access to thewater source can reduce the amountof contaminants that have to beremoved from the water (Figure 6.2).In many cases, restoring a sewage

collection and treatment system maybe a greater priority than completelyrehabilitating the water treatmentworks.

Staged rehabilitationThe priority for treatment worksrehabilitation is shown in Figure6.4 overleaf. If, however, the wateris relatively clear, chlorination canbe introduced at an earlier stage.This may involve the installationof temporary pipelines to by-pass damaged sections of theplant. If major components of theworks such as storage reservoirsand sedimentation tanks arebadly damaged, their repair orreplacement will be expensiveand take a long time. During theemergency phase they should bereplaced with temporary equipmentsuch as portable storage tanks.

Pumps and powerPumps (and the motors that drivethem) are essential components of many treatment works. They havea variety of uses such as raising

water from the intake into the works,between different elements in theworks, or for adding and mixingchemicals. It will be essential tothe overall operation of the worksthat they function well, so theirrehabilitation must be a priority.Replacement parts may take time

to be delivered, so ask an engineerto make an early assessment of thestate of the pumps.

Power is also essential and anadditional priority. If the mainssupply is not working, install mobilegenerators.

Works operation As soon as components of thetreatment works have been re-commissioned, their operationwill need to be sustained. This willinclude:

Monitoring: The quality

and quantity of water beingproduced by the works shouldbe measured regularly to checkwhether everything is workingcorrectly and that the outputmeets minimum standards(see the Sphere Guidelinesfor minimum standards foremergency water supplies).Simple test kits are available formeasuring basic parameters of water quality. Sources of further

information are given onpage 6.4.

Chemicals: Modern treatmentworks rely on the addition of chemicals to aid the treatmentprocess. These include alumto help settlement, lime for

Agriculturalpollution andsoil erosion

Excreta, solid wasteand stormwater

Chemicalpollution

Figure 6.2. Preventing pollution upstream as shown will reduce the need for treatment


25/64


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Further information

Le Chevallier, M.W. and Au, K.K. (2004) Water Treatment and Pathogen Control: Process efficiency in achieving safe drinking water , WHO/IWA Publishingat: http://www.who.int/water_sanitation_health/dwq/9241562552/en/index.html

Twort, A.C. et al. (2000) Water Supply, 5th ed. Arnold withIWA Publishing: London

Sphere (2004). Humanitarian Charter and MinimumStandards in Disaster Response , The Sphere Project:Geneva, Switzerland (Distributed worldwide by OxfamGB) http://www.sphereproject.org/

Rehabilitating water treatment works after an emergency

Prepared for WHO by WEDC. Authors: Brian Reed and Bob Reed. Series Editor: Bob Reed.Editorial contributions, design and illustrations by Rod ShawLine illustrations courtesy of WEDC / IFRC. Additional graphics by Ken Chatterton.


6.4




adjusting the pH of the waterand chlorine for disinfection. Itmay take a long time to replenishsupplies so the need for chemicalsshould be identified and supplierscontacted as soon as possible.

A reduced level of treatment canbe provided if chemicals arein short supply, using point of use disinfection where it is mostneeded, such as in hospitals andschools.

Maintenance: This includesmanual tasks, such as cleaningscreens, removing settled sludgeand lubricating pumps. The filterswill become clogged with solids.Pipes will need to be checked forleaks.

Public informationThe public should be kept informedof developments. This will easeconcerns about water availability andhelp to reduce wastage, particularlyif the public can help identify leaks inthe distribution system.

River source

Intake Delivery pipe network

Screen Water storage

Coagulation Chlorination

Sedimentation Filtration

Water intake and delivery pipe network

Coagulation and chlorination

Primary screening

Sedimentation and filtration

Figure 6.4. Water treatment in stages


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Solid waste managementin emergencies

7

The safe disposal of solid waste is critical for public health, and isespecially true during an emergency. Not only will existing collection anddisposal systems be disrupted, but there will be extra waste caused bythe emergency itself. Initially, for camps of displaced people or refugeesand similar new sites, there will be no arrangements in place at all. Ifsolid waste is not dealt with quickly, serious health risks will develop

which will further demoralize the community already traumatized by theemergency. This technical note highlights the key issues to consider inmanaging solid waste during and shortly after a disaster.

What is solid waste?In this technical note, the term solidwaste is used to include all non-liquid wastes generated by humanactivity and a range of solid wastematerial resulting f rom the disaster,such as:

general domestic garbage suchas food waste, ash and packagingmaterials;

human faeces disposed of ingarbage;

emergency waste such as plasticwater bottles and packaging fromother emergency supplies;

rubble resulting from the disaster; mud and slurry deposited by the

natural disaster; and

fallen trees and rocks obstructingtransport and communications.

Other specialist wastes, such asmedical waste from hospitals andtoxic waste from industry, will alsoneed to be dealt with urgently, butthey are not covered by this technicalnote.

Box 7.1. Health risks related to the inadequate management ofsolid wasteFlies, rats, dogs, snakes and other scavengers are attracted togarbage, particularly in hot climates. If food is scarce, people may beforced to scavenge as well which will lead to increased cases of disease(e.g. dysentery).

Pools of rainwater associated with wastecollection will propagate the breeding of mosquitoes that transmit malaria, dengue andyellow fever. Heaps of garbage present a fire riskand smoke can also be a health hazard if theburning waste contains items such as plastics orchemicals. Breathing difficulties can arise fromthe fungi that develop on garbage tips. Sharpitems such as needles and broken glass presenta further hazard to people walking through thearea. Garbage washed by rain can contaminatewater supplies. Indiscriminate dumping of waste

can block water courses causing flooding. Wasteis unsightly and lowers the morale of communities.

There could also be a large numberof dead bodies to dispose of duringand after an emergency (seeTechnical Note 8).

The objective of managingsolid wasteThe Sphere standards state thatpeople should be able to live in anenvironment that is uncontaminated

by solid waste, including medicalwaste, and have the means todispose of their domestic wasteconveniently and effectively.

In addition to this objective there

is also the need to make theenvironment safe and provideaccess for people and services inthe area.


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Solid waste management in emergencies

AssessmentIt is important to assess the issuesand priorities before beginningwork. Consider the following:

Waste streams What types and volumes of

wastes are there and how muchis being produced each day?

How is waste currently disposedof (if at all)?

Who (if anyone) is responsiblefor waste collection and disposaland what resources do theyhave?

What is the quantity and whatare the types of waste that have

been produced by the disaster,and where are they situated?

Waste problems Are the current waste disposal

systems coping with the volumeof waste?

Are there any hazardous wastesthat require special attention(such as medical waste)?

Can the organizationsresponsible for waste collectioncope with the demand?

Are steps being taken to dealwith the wastes produced by thedisaster? Are these sufficient?

Are there suitable disposalfacilities for all wastes beingproduced?

Disposal of waste causedby a disasterDisasters such as floods,

earthquakes and hurricanes(cyclones) can produce largequantities of rubble. This will bea danger to people, block accessroads, conceal trapped personsand block drainage channels. Itwill also hinder the access of otheremergency services (Figure 7.1).

Once all survivors have beenreleased from the rubble (theycan survive for up to seven days),its removal and the demolition of dangerous structures should bea priority. If there is no approvedwaste disposal site near by, the

wastes can be piled, in the shortterm, on areas of waste land. Notall rubble is waste. Items such aszinc roofing sheets, furniture andbricks can be reused. If possiblesort the rubble as it is being

removed, storing reusable materialsseparately from the rest of thewaste. Waste piles can be a seriousfire risk so provide a security fenceto keep out the public and ban theuse of all naked flames, includingcigarettes.

Work with the communityPeople affected by major disastersare badly traumatized. Giving thema task to perform can help them

overcome the trauma. Employneighbourhood groups to clean uptheir areas. This will bring moneyinto the communities and strengthentheir links with their areas. Introducea rotation system so that all familiesin the community can benefit.

Protect the workforceThe workforce should be protectedfrom physical injury by the provisionof masks, overalls, gloves andboots (Figure 7.2). They shouldbe vaccinated against commondiseases such as tetanus.

Consult local health services foradvice on vaccination.

Domestic waste A major disaster will not stoppeople producing garbage butthe content may change. If peoplehave stayed close to their homesit is best to support the use of traditional practices. In rural areasthis is likely to be burial, either withinthe family compound or in sharedneighbourhood pits.

Most urban areas will have had someform of communal collection systemprior to the emergency. It may be

necessary to set one up and supportit financially, by supplying vehiclesand by employing personnel. Whenrecruiting people, hire from the localcommunity.

Collection and transportIn the early stages of an emergency,provide communal storage bins(Figure 7.3). As the situationstabilizes, the number of bins can begradually increased to the density

there was before the disaster.Immediately after a disaster, a 100litre container will serve 200 people.This drops to 50 people per containerin the long term.

The type of transport used formoving the garbage from bins toits final point of disposal dependson the quantity of waste produced,the distance over which it has tobe transported and available localresources. Box 7.2 illustrates some of the common vehicles used.

Figure 7.1. Disasters can produce largequantities of rubble

Figure 7.2. Provide the workforce withprotective clothing


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CampsFor low-density refugee camps,the best waste disposal option isthe family solid waste pit similar tothose used in rural communities. If

the plot size is too small for family

Figure 7.3. Provide communal storage binsfor domestic waste in the early stages of anemergency

pits, treat the camp like an urbanarea by using communal pits orlarger disposal sites away from thecamp.

Earth mound tokeep surface waterout of the pit

Fence aroundthe pit

Waste layers

Once full, backfillthe pit with at least0.5m of soil cover

Wire meshcoveringpit contents

0.1m layer ofsoil/ash to covereach layer of waste

Figure 7.4. A communal pit

DisposalExisting urban areas will almostcertainly have established wastedisposal sites. Use these if possible.If they cannot be used, set up

temporary disposal sites such ascommunal pits similar to the typeshown in Figure 7.4.

Box 7.2 Solid waste collection and transportationWhen selecting a suitable vehicle for transportation of waste, the wastegeneration rates and densities need to be considered along with theareas they need to access, such as narrow alleys or uneven paths, andthe distance between collection and disposal points.


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Further information

Harvey, P., Baghri, S and Reed, R. A. (2002) Emergency Sanitation: Assessment and Programme Design, WEDC, Loughborough, UK.

OXFAM (Undated) Domestic and refugee camp wastein Technical Briefing Notes on Waste Management

in Emergencies Final draft , Oxfam GB and GoldersUK. http://www.oxfam.org.uk/resources/downloads/emerg_manuals/tbn_refugee_waste.doc

OXFAM (Undated) Compost and recycling inemergencies in Technical Briefing Notes on WasteManagement in Emergencies Final draft, Oxfam GBand Golders UK. http://www.oxfam.org.uk/resources/downloads/emerg_manuals/tbn_composting.doc

OXFAM (Undated) Large-scale environmental clean-upcampaigns in Technical Briefing Notes on WasteManagement in Emergencies Final draft, Oxfam GB

and Golders UK. http://www.oxfam.org.uk/resources/downloads/emerg_manuals/tbn_large_scale_cleanup.doc

OXFAM (Undated) Hazardous waste in Technical BriefingNotes on Waste Management in Emergencies Final draft, Oxfam GB and Golders UK. http://www.oxfam.org.uk/resources/downloads/emerg_manuals/tbn_hazardous_wastes.doc

Sphere (2004). Humanitarian Charter and MinimumStandards in Disaster Response , The Sphere Project:Geneva, Switzerland (Distributed worldwide by OxfamGB) http://www.sphereproject.org/

Wisner, B. and Adams, J. (2002) Environmental Health in

Emergencies and Disasters . WHO Geneva.http://www.who.int/water_sanitation_health/emergencies/emergencies2002/en/index.html


Prepared for WHO by WEDC. Authors: Jonathan Rouse and Bob Reed. Series Editor: Bob Reed.Editorial contributions, design and illustrations by Rod ShawLine illustrations courtesy of WEDC / IFRC. Additional graphics by Ken Chatterton.


7.4




Other important issuesCommunity issuesIt is useful and important toconsult potential users of a waste

management system before andduring its design, construction anduse. This is particularly true fora displaced community as some

people may not be accustomed tousing a communal system.

RecyclingRecycling should be encouraged

and managed properly as itprovides a local source of incomeand reduces the amount of waste fordisposal.

Other disposal methodsDisposal systems such ascomposting, incineration andsanitary landfill can be consideredonce the situation has stabilized.They are unlikely to be a first phase

emergency response activity.

ManagementThe key to effective solid wastecollection and disposal is goodmanagement. It is often necessary tosupport local institutions with fundsand professional staff to enable themto meet their responsibilities.

Figure 7.6. Involving professional staff

Figure 7.5. Consulting with the community


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Disposal of dead bodiesin emergency conditions

8

Dealing with the dead is one of the most difficult aspects ofa disaster reponse. This is not so much due to health-relatedrisks, which tend to be negligible, but to the psychological,social and political impact of the trauma. This technical noteoutlines the health implications of dealing with mass fatalitiesand priority actions that need to be considered when planning

for the collection and disposal of the dead.

Health risks from massfatalitiesContrary to common belief, thereis no medical evidence to suggestthat large numbers of dead bodies,in themselves, cause disease orepidemics. Human remains origin-ating from traumatic events (natural

disasters, accidents or warfare donot represent a health hazard. Theonly situation where there is a healthrisk is when communicable diseasehas been the cause of the fatalities.

This technical note focuses on thepriority tasks for dealing with deadbodies not caused by medicalepidemics.

Much of the information given in thisnote is draws on Morgan et al. (2006).It is strongly recommended that, if youare likely to be involved in the disposalof dead bodies, you should consultthis text first.

Priority tasksBeyond injury, the primary healthconcern for survivors of a disasteris the psychological trauma of theloss of loved ones and of witnessingdeath on a large scale (Figure 8.1).For this reason it is important toproceed with the collection of deadbodies as soon as possible, but it isnot necessary or advisable to hurrytheir disposal.

Deal with the living firstIn all cases, priority should be givento the living. Search and rescueshould not be held up becauseof concerns about the dead, norshould health care resources (e.g.ambulances and hospital beds) beused to deal with them.

Protect the workforceBody recovery often takes placespontaneously by groups from thesurviving community, volunteers, andsearch and rescue teams. Recoveryteams should wear protectiveequipment such as gloves and boots.They should also be encouraged towash their handswith soap afterhandling deadbodies.

Recovery teamsalso face risks fromworking in dangerousenvironments. Try tovaccinate workers against tetanusand ensure first aid and medicaltreatment is available in case of injury(Figure 8.2).

Figure 8.1.The loss of loved ones

Figure 8.2.A first aid kit


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Disposal of dead bodies in emergency conditions

The handling of large numbers of dead bodies can have a seriousimpact on the mental health of members of the recovery team. Theeffects can take a variety of forms andmay occur immediately after the eventor much later. Health services must beprepared for this and deal with it asand when it arises (Figure 8.3).

Body recoveryBodies should be recovered asquickly as possible, but withoutinterrupting other activities aimed athelping survivors. Rapid recoveryaids identification and reduces thepsychological effects on survivors.

Bodies should be placed in bodybags. If these are not available, useplastic sheets, shrouds, or otherlocally-available materials. Separatebody parts such as arms or legsshould be treated as individualbodies. Do not try to match severedparts at the disaster site.

Personal belongings should bekept with the body. They will aid

identification and may have legaland psychological implications forsurvivors.

Keep details of the place and datewhen the body was found, using aform similar to that shown in Box 8.1.

Give the body a unique referencenumber, copy it on to waterproof

labels and attach these to both thebody and its container. Labels shouldnot be removed until the body hasbeen collected by rela

who emergency

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