Household Water Treatment:Household Water Treatment: effectiveness, cost effectiveness effectiveness, cost effectiveness

and other recent research and other recent research

Thomas Clasen, PhDThomas Clasen, PhDDisease Control & Vector Biology UnitDisease Control & Vector Biology Unit

Department Infectious & Tropical DiseasesDepartment Infectious & Tropical DiseasesLondon School of Hygiene & Tropical MedicineLondon School of Hygiene & Tropical Medicine

SummarySummary

Refining the dominant paradigmRefining the dominant paradigmCochrane review: water quality Cochrane review: water quality interventions to prevent interventions to prevent diarrhoeadiarrhoeaWHO CostWHO Cost--effectiveness analysiseffectiveness analysisResearch UpdateResearch Update

Environmental Barriers Environmental Barriers to to FaecalFaecal--Oral TransmissionOral Transmission

Primary BarrierPrimary BarrierSanitation (proper Sanitation (proper excreta disposal)excreta disposal)

Hygiene (hand Hygiene (hand washing)washing)

Secondary BarriersSecondary BarriersWater quality (treatment Water quality (treatment & safe storage)& safe storage)

Water quantity Water quantity (personal and domestic (personal and domestic hygiene)hygiene)

Hygiene (especially Hygiene (especially hand washing)hand washing)

Proper cooking/food Proper cooking/food handing practiceshanding practices

Reduction in Reduction in DiarrhoeaDiarrhoea

from from Improvements in Water QualityImprovements in Water Quality

Expected reduction in Expected reduction in diarrhoealdiarrhoeal

disease morbidity from improvements in disease morbidity from improvements in one or more components of water and sanitation (one or more components of water and sanitation (EsreyEsrey, 1991), 1991)

All StudiesAll Studies Rigorous StudiesRigorous Studies

No. StudiesNo. Studies ReductionReduction No. StudiesNo. Studies Reduction Reduction

Water and SanitationWater and Sanitation 77 20%20% 22 30%30%

SanitationSanitation 1111 22%22% 55 36%36%

Water Quality and Water Quality and QuantityQuantity 2222 16%16% 22 17%17%

Water QualityWater Quality 77 17%17% 44 15%15%

Water QuantityWater Quantity 77 27%27% 55 20%20%

HygieneHygiene 66 33%33% 66 33%33%

Interventions at SourceInterventions at Source

Interventions at the HouseholdInterventions at the Household

Ethiopia 2005 DHSEthiopia 2005 DHS

38.4% (43.8% rural) rely on 38.4% (43.8% rural) rely on unimproved water sourcesunimproved water sources

25.9% (30.1%) use surface 25.9% (30.1%) use surface waterwater

91.9% (91.4%) do not treat 91.9% (91.4%) do not treat their water before drinkingtheir water before drinking

5.2% (4.6%) strain water 5.2% (4.6%) strain water through a cloththrough a cloth

2.4% (2.4%) boil their water 2.4% (2.4%) boil their water before drinkingbefore drinking

What about boiling?What about boiling?SubSub--optimal microbiological performance, probably optimal microbiological performance, probably due to recontamination after boiling (Gupta 2006; due to recontamination after boiling (Gupta 2006; HandzelHandzel 2007; Clasen 2008).2007; Clasen 2008).Potentially high cost: US$7.99 to US$8.34 per Potentially high cost: US$7.99 to US$8.34 per household per year in India (McLaughlin 2006); household per year in India (McLaughlin 2006); US$3.24 to US$20.16, in Vietnam) (do Hoang 2007)US$3.24 to US$20.16, in Vietnam) (do Hoang 2007)Indoor air pollution from cooking with biomass Indoor air pollution from cooking with biomass associated with reduced birth weight, respiratory associated with reduced birth weight, respiratory infections, anemia, stunting (infections, anemia, stunting (RetherfordRetherford 2006)2006)Boiling water at home is also associated with higher Boiling water at home is also associated with higher levels of burn accidents . In Sao Paulo, Brazil, boiling levels of burn accidents . In Sao Paulo, Brazil, boiling water was responsible for 59% of burn accidents water was responsible for 59% of burn accidents among children under 3 years (Rossi 1998). among children under 3 years (Rossi 1998). Other issues: Acceptability, environmental Other issues: Acceptability, environmental sustainabilitysustainability

Systematic ReviewsSystematic Reviews——Wright et al.*Wright et al.*Systematic review and metaSystematic review and meta--analysis of 57 studies measuring analysis of 57 studies measuring bacteria counts for source water bacteria counts for source water and stored water in the home.and stored water in the home.Results: The bacteriological Results: The bacteriological quality of drinking water quality of drinking water significantly declined after significantly declined after collection in many settings. collection in many settings. Conclusion: Policies that aim to Conclusion: Policies that aim to improve water quality through improve water quality through source improvements may be source improvements may be compromised by postcompromised by post--collection collection contamination. Safer household contamination. Safer household water storage and treatment is water storage and treatment is recommended to prevent this, recommended to prevent this, together with pointtogether with point--ofof--use water use water quality monitoring.quality monitoring.*Wright J, Gundry S, Conroy R (2004). Household drinking water in developing countries: a systematic review of microbiological contamination between source and point-of-use. Tropical Med. Int’l Health 9(1): 106-117

Effectiveness Data: Cochrane Review

Clasen T, Roberts I, Clasen T, Roberts I, RabieRabie

T, Schmidt T, Schmidt W, W, CairncrossCairncross

S. Interventions to S. Interventions to improve water quality for preventing improve water quality for preventing diarrhoea (A Cochrane Review). In: The diarrhoea (A Cochrane Review). In: The Cochrane Library, Issue 3, 2006. Cochrane Library, Issue 3, 2006.

Effectiveness: Intervention Type (all age)Effectiveness: Intervention Type (all age)

Summary of EffectivenessSummary of Effectiveness——All agesAll agesIntervention Type Intervention Type

(no. trials)(no. trials)

EstimateEstimate

(random)(random)

% % ΔΔ(1(1--RR)RR)

95% CI of 95% CI of EstimateEstimate

Heterogeneity*Heterogeneity*

(Chi(Chi--square)square)

Source (6)Source (6) 0.730.73 27%27% 0.53 to 1.010.53 to 1.01 p<0.00001p<0.00001

Household (32)Household (32) 0.530.53 47%47% 0.39 to 0.730.39 to 0.73 p<0.00001p<0.00001

Filtration (6)Filtration (6) 0.370.37 63%63% 0.28 to 0.490.28 to 0.49 p=0.56p=0.56

Chlorination (16)Chlorination (16) 0.630.63 37%37% 0.52 to 0.750.52 to 0.75 p<0.00001p<0.00001

Solar Disinfection (2)Solar Disinfection (2) 0.690.69 31%31% 0.63 to 0.740.63 to 0.74 p=0.73p=0.73

FloccFlocc/Disinfection (7)/Disinfection (7) 0.480.48 52%52% 0.20 to 1.160.20 to 1.16 p<0.0001p<0.0001

Flocc/DisinfFlocc/Disinf

(ex (ex DoocyDoocy*)*) 0.690.69 31%31% 0.58 to 0.820.58 to 0.82 p=0.08p=0.08

ImprImpr. Storage (1). Storage (1) 0.790.79 21%21% 0.61 to 1.030.61 to 1.03 n.an.a..

*Note that in a test for heterogeneity, a low p-value (e.g. <0.10) suggests an actual underlying difference in effect between studies that is unlikely

to be attributable to chance.

*Doocy

S, Burhnam

G (2006). Point-of-use water treatment and diarrhoea

reduction in the emergency context: an effectiveness trial in Liberia. Trop Med Int

Health. 11(10):1542-52

Summary of EffectivenessSummary of Effectiveness——Under 5sUnder 5sIntervention Type Intervention Type

(no. trials)(no. trials)

EffectEffect

(random)(random)

% % ΔΔ(1(1--RR)RR)

95% CI of 95% CI of EstimateEstimate

HeterogeneityHeterogeneity

(Chi(Chi--square)square)

Source (4)Source (4) 0.850.85 15%15% 0.71 to 1.020.71 to 1.02 p=.007p=.007

Household (25)Household (25) 0.560.56 44%44% 0.39 to 0.810.39 to 0.81 p<0.00001p<0.00001

Filtration (5)Filtration (5) 0.360.36 64%64% 0.24 to 0.530.24 to 0.53 p=0.37p=0.37

Chlorination (12)Chlorination (12) 0.760.76 24%24% 0.67 to 0.860.67 to 0.86 p=0.004p=0.004

Solar Disinfection (0)Solar Disinfection (0) nana nana nana nana

FloccFlocc/Disinfection (7)/Disinfection (7) 0.520.52 48%48% 0.20 to 1.370.20 to 1.37 p<0.00001p<0.00001

Flocc/DisinfFlocc/Disinf

(6)((6)(ex ex DoocyDoocy*)*) 0.710.71 29%29% 0.61 to 0.840.61 to 0.84 p=0.10p=0.10

ImprImpr. Storage (1). Storage (1) 0.690.69 31%31% 0.47 to 0.810.47 to 0.81 n.an.a..

Effectiveness under various conditionsEffectiveness under various conditions

Compliance Compliance (use of the (use of the intervention)intervention)

>50% Compliance (n=16*)>50% Compliance (n=16*)

0.46 (0.32 to 0.83)0.46 (0.32 to 0.83)

P<0.0001P<0.0001

<50% Compliance (n=5)<50% Compliance (n=5)

0.75 (0.63 to 0.90)0.75 (0.63 to 0.90)

P=0.06P=0.06

SanitationSanitation

((WHO/UNICEF WHO/UNICEF definitions)definitions)

Improved (n=11)Improved (n=11)

0.48 (0.38 to 0.62)0.48 (0.38 to 0.62)

P=0.02P=0.02

Unimproved (n=8*)Unimproved (n=8*)

0.67 (0.55 to 0.81)0.67 (0.55 to 0.81)

P<0.00001P<0.00001

Water Supply Water Supply ((WHO/UNICEF WHO/UNICEF definitions)definitions)

Improved (n=11)Improved (n=11)

0.57 (0.46 to 0.72)0.57 (0.46 to 0.72)

P=0.01P=0.01

Unimproved (n=24*)Unimproved (n=24*)

0.66 (0.55 to 0.72)0.66 (0.55 to 0.72)

P<0.00001P<0.00001

Water Quantity Water Quantity (Sphere Project minimums)(Sphere Project minimums)

15L/person/day(n=7)15L/person/day(n=7)

0.56 (0.44 to 0.71)0.56 (0.44 to 0.71)

P=0.005P=0.005

<15L/person/day (n=3*)<15L/person/day (n=3*)

0.880.88

(0.(0.772 to 1.2 to 1.0808) ) PP=0.01=0.01

Water QualityWater Quality 1010--99 FC/100ml (n=14)99 FC/100ml (n=14)

0.70 (0.60 to 0.80)0.70 (0.60 to 0.80)

P<0.00001P<0.00001

100+ FC/100ml (n=7)100+ FC/100ml (n=7)

0.69 (0.49 to 0.96)0.69 (0.49 to 0.96)

P=0.007P=0.007

*Excludes Doocy, 2006

Conclusions on EffectivenessConclusions on Effectiveness

The review includes 38 trials covering over 53,000 subjects The review includes 38 trials covering over 53,000 subjects from 19 countries over 20 yearsfrom 19 countries over 20 yearsIn settings with sufficient water quantity, interventions to In settings with sufficient water quantity, interventions to improve water quality are protective against endemic improve water quality are protective against endemic diarrhoeadiarrhoeaInterventions at the household level are about twice as Interventions at the household level are about twice as effective as those at the sourceeffective as those at the sourceEffectiveness increased with compliance Effectiveness increased with compliance Effectiveness improves with, but is not conditioned upon, Effectiveness improves with, but is not conditioned upon, the presence of improved sanitation. Effectiveness is the presence of improved sanitation. Effectiveness is independent of improved independent of improved vsvs unimproved water supplyunimproved water supplyEffectiveness was higher among better quality studies, but Effectiveness was higher among better quality studies, but the only blinded trials consistently showed no statistically the only blinded trials consistently showed no statistically significant protection from water quality interventionssignificant protection from water quality interventions

CostCost--EffectivenessEffectivenessA comparison of various A comparison of various interventions on a sectorinterventions on a sector--wide wide basis.basis.Unlike costUnlike cost--benefit analysis benefit analysis (where all benefits(where all benefits——improved improved productivity, increased school productivity, increased school time, etc.time, etc.——are included in the are included in the calculus), CEA is concerned calculus), CEA is concerned with the with the realization of a social realization of a social objective, such as the objective, such as the prevention of disease prevention of disease The output of a CEA is a ratio The output of a CEA is a ratio (the cost(the cost--effectiveness ratio) effectiveness ratio) between the cost of the between the cost of the intervention the disability intervention the disability adjusted life years (adjusted life years (DALYsDALYs) ) averted as a result of the averted as a result of the intervention. intervention.

Clasen T, Haller L, Walker D, Bartram J, Cairncross

S (2007). Cost-effectiveness analysis of water quality interventions for preventing diarrhoeal disease in developing countries. J. Water & Health 5(4):599-608

Hardware Costs (US$)Hardware Costs (US$)Product Unit Cost Volume of

Water Treated

Cost per 10,000L of Water Treated

First Year Cost1

Three Year Cost1

Boiling (fuel only) India-woodVietnam-wood

$0.012-0.024$0.009 – 0.056

10L7L

$12.00 - $24.00$29.99-$168.64

$10.95 -$21.90$3.26 - $20.16

$32.85 - $65.70$9.81- $60.48

WaterGuard™ (PSI brand of sodium hypochlorite1

$0.45 1,000 $4.50 $4.10 $12.32

Gravity filter with two 15cm Stefani® candles4

$15.00 20,000L $7.50 $15.00 $30.00

Sodis Solar Disinfection5 $0.40 730L $5.48 $0.80 $2.40

Procter & Gamble PUR® Sachet6

$0.10 10L $100.00 $91.25 $273.75

BioSand Filter $12.00-$40.00 Unlimited $12.00-$40.00 $12.00-$40.00 $12.00-$40.00

Hindustan Lever Pureit®3 $34.00 1,500L $57.00 $36.50 $46.50

Medentech Aquatabs® 0.0927 200L $4.60 $4.18 $12.60

Table assumptions and sources:1. Based on 25L/day/household, or 9,125L/year, except boiling which is based on 10L/day for India and 7L/day in Vietnam.2. 150ml bottle of 1.25% sodium hypochlorite designed to treat 1000L sold at retail in Tanzania and assuming full cost recovery (not subsidized); production cost is $0.17 per bottle (Clasen, 2006a).3. Rs1600 for unit; Rs250 consumables every 6 months or 1500L. (Clasen 2006)4. $3.75 per candle, plus $7.50 for vessels and valves. 5,000L capacity per candle according to manufacturer. Replace candles each year. Replace vessels and valve after 3 years. (Clasen 2004)5. $0.10 per bottle (mean price based data from 6 countries) x recommended 4 bottles per household, used for 6 months; capacity based on 2 x 2L bottles (alternate 2 bottles in sun, 2 bottles in household each day) (M. Wegelin personal communication).6. Manufacturer’s suggested retail price of $0.10 per sachet. Assumes no further expenditure for mixing and storing vessels.7. PSI retail target price in Tanzania for strip pack of 10 x 20L tablets.

Estimating costsEstimating costsCost data for construction and maintenance of nonCost data for construction and maintenance of non--reticulated reticulated sourcesource--based interventions came from WHO databasesbased interventions came from WHO databases

useful life of the systems (20 years), plus 5% for operation useful life of the systems (20 years), plus 5% for operation and maintenance, plus 5% (dug wells and boreholes) or 10% and maintenance, plus 5% (dug wells and boreholes) or 10% (stand posts) for water resource protection (stand posts) for water resource protection

Cost data for householdCost data for household--based interventions were collected based interventions were collected from programme implementers responding to special cost from programme implementers responding to special cost protocol protocol

chlorination (estimates from chlorination (estimates from 17 country 17 country programmesprogrammes))filtration (estimates from filtration (estimates from 4 4 programmesprogrammes of locallyof locally--fabricated fabricated and commercial ceramic filters )and commercial ceramic filters )solar disinfection (estimates from solar disinfection (estimates from 13 country 13 country programmesprogrammes))flocculation / disinfection (estimates from flocculation / disinfection (estimates from 5 country 5 country programmesprogrammes) )

For each intervention, a mean and range of costs were For each intervention, a mean and range of costs were computedcomputedEstimated US$ (2002) per person covered per yearEstimated US$ (2002) per person covered per year

Summary of Cost EstimatesSummary of Cost Estimates

$0.66

$1.88

$2.61

$3.60

$3.03

$0.63

$4.95

$-

$1.00

$2.00

$3.00

$4.00

$5.00

$6.00

Source-Africa Source-Asia Source-LA&C Chlorination CeramicFiltration

SolarDisinfection

Flocculation-Disinfection

System

Cos

t

Annual cost per person in US$ of source and household interventions (error bars represent range of costs from programmes)

Health Cost OffsetsHealth Cost OffsetsCosts Averted Variable Data Source Data value (and range)

Health sector expenses averted due to prevention of diarrhoeal disease

Unit cost per treatment WHO regional unit cost data

$4.30-$9.70 per visit$16.10-$39.70 per day

Number of cases WHO BoD

data Variable by region

Visits or days per case Expert opinion 1 outpatient visit per case (0.5-1.5); 5 days for hospitalized cases

Probably much less than 0.5.

Hospitalisation rate WHO Data 91.8% ambulatory

Patient (householder) costs averted due to prevention of diarrhoeal disease

Transport cost per visit Assumptions $0.50 per visit

% patients using transport

Assumptions 50% of patients

Number of cases WHO BoD

data Variable by region

Visits or days per case Expert opinion 1 outpatient visit per case (0.5-1.5); 5 days for hospitalized cases

Hospitalization rate WHO data 91.8% ambulatory

Adapted from Hutton & Haller (2004). Evaluation of the Costs and Benefits of Water and Sanitation Improvements at the Global Level. Geneva: World Health Organization

Gross and Net Costs (50% Coverage)Gross and Net Costs (50% Coverage)Epidemiological SubEpidemiological Sub-- Region (and countries)Region (and countries)

InterventionIntervention Gross Annual Cost Gross Annual Cost (and range*) in (and range*) in US$ millionsUS$ millions

Annual Annual Health Health Cost Cost Offsets Offsets in US$ in US$ millionsmillions

Net Net Annual Annual Cost in Cost in US$ US$ millionsmillions

AfrAfr--E (Botswana, E (Botswana, Burundi, Central African Burundi, Central African Republic, Congo, Cote Republic, Congo, Cote dd’’Ivoire, Democratic Ivoire, Democratic Republic of the Congo, Republic of the Congo, Eritrea, Eritrea, EthiopiaEthiopia, Kenya, , Kenya, Lesotho, Malawi, Lesotho, Malawi, Mozambique, Namibia, Mozambique, Namibia, Rwanda, South Africa, Rwanda, South Africa, Swaziland, Uganda, Swaziland, Uganda, United Republic of United Republic of Tanzania, Zambia, Tanzania, Zambia, Zimbabwe)Zimbabwe)

SourceSource 128.4 (50.6128.4 (50.6--336.8)336.8) 121.0121.0 7.37.3

Household Household chlorinationchlorination

104.7 (104.7104.7 (104.7--599.4)599.4)229.9229.9 --125.2125.2

Household Household filtrationfiltration

480.5 (320.3480.5 (320.3--610.5)610.5)391.4391.4 89.189.1

Household solar Household solar disinfectiondisinfection

101.5 (76.1101.5 (76.1--139.5)139.5) 192.6192.6 --91.191.1

Household Household flocculation flocculation disinfectiondisinfection

785.0 (157.0785.0 (157.0--785.0)785.0) 192.6192.6 592.4592.4

*Based on range of cost estimates per person per year for each intervention

Calculating Calculating DALYsDALYs

AvertedAvertedUses Uses WHOWHO’’ss PopModPopMod to simulate the effect of a 10to simulate the effect of a 10--year year intervention on a population over 100 yearsintervention on a population over 100 yearsAs the risk of diarrhoea varies with water and sanitation As the risk of diarrhoea varies with water and sanitation coverage levels, the population was then distributed coverage levels, the population was then distributed among the various exposure scenarios for water and among the various exposure scenarios for water and sanitation (sanitation (PrPrüüssss 2002)* prevailing in each country based 2002)* prevailing in each country based on the Global Water Supply and Sanitation Assessment on the Global Water Supply and Sanitation Assessment (WHO/UNICEF 2000). (WHO/UNICEF 2000). The relative risk of diarrhoea was then entered for each The relative risk of diarrhoea was then entered for each subsub--population based on WHO estimates for risks population based on WHO estimates for risks associated with unsafe water (associated with unsafe water (PrPrüüssss--ŰŰststüünn 2004). These, 2004). These, in turn, are based on published reviews, large surveys in turn, are based on published reviews, large surveys and multiand multi--country studies. country studies.

*VI (no improved water supply and no basic sanitation in a count*VI (no improved water supply and no basic sanitation in a country which is not extensively covered by those services, and wherery which is not extensively covered by those services, and where

water water supply is not routinely controlled; supply is not routinely controlled; VbVb

(improved water supply and no basic sanitation in a country whi(improved water supply and no basic sanitation in a country which is not extensively covered by ch is not extensively covered by those services, and where water supply is not routinely controllthose services, and where water supply is not routinely controlled); ed); VaVa

(improved sanitation but no improved water supply in a country (improved sanitation but no improved water supply in a country which is not extensively covered by those services and where watwhich is not extensively covered by those services and where water supply is not routinely controlled); IV (improved water suppler supply is not routinely controlled); IV (improved water supply and y and improved sanitation in a country which is not extensively covereimproved sanitation in a country which is not extensively covered by those services, and where water supply is not routinely cond by those services, and where water supply is not routinely controlled)trolled)

Annual Annual DALYsDALYs

Averted Averted EpidemiologicEpidemiologic al Subal Sub--Region Region

InterventionIntervention Annual Annual DALYsDALYs averted (and range*) averted (and range*) in millionsin millions

AfrAfr--E E SourceSource 1.05 (0 to 3.65)1.05 (0 to 3.65)

Household chlorinationHousehold chlorination 1.99 (1.341.99 (1.34--2.58)2.58)

Household filtrationHousehold filtration 3.4 (2.743.4 (2.74--3.87)3.87)

Household solar disinfectionHousehold solar disinfection 1.67 (1.341.67 (1.34--1.99)1.99)

Household Household flocculation/disinfectionflocculation/disinfection

1.67 (0.971.67 (0.97--2.26)2.26)

*Based on 95% confidence interval around pooled estimate of effectiveness

Interpreting CE dataInterpreting CE dataFollowing the recommendation of the Following the recommendation of the CMH, WHO uses the following CMH, WHO uses the following categories to determine cost categories to determine cost effectiveness:effectiveness:

$ per DALY averted < GNI per capita = $ per DALY averted < GNI per capita = ““highly CEhighly CE””$ per DALY averted 1$ per DALY averted 1--3 * GNI per 3 * GNI per capita = capita = ““CECE””$ per DALY averted > 3* GNI per $ per DALY averted > 3* GNI per capita = capita = ““not CEnot CE””

AfrAfr--E GNI per capita: $369E GNI per capita: $369

CostCost--effectiveness ratios*effectiveness ratios*Sub-

Region Intervention Cost per DALY

averted (and range**) in US$s

Cost effectiveness (CMH Benchmark)

Afr-E Source 123 (14-322) Highly cost effective

Household chlorination 53 (41-447) Highly cost effective

Household filtration 142 (83-223) Highly cost effective

Household solar disinfection

61 (38-104) Highly cost effective

Household flocculationdisinfection

472 (70-813) Cost effective (Highly CE at net cost of US$354)

*Gross cost, excluding health cost offsets **Minimum/maximum costs; 95%CI of effectiveness

CostCost--effectiveness Planeeffectiveness PlaneCE Plane--Afr-E (100% coverage)

0

200

400

600

800

1000

1200

1400

1600

1800

0 1 2 3 4 5 6 7 8

Yearly DALYs Averted (millions)

Year

ly C

ost (

US$

mill

ions

)

HH Solar Disinfection

HH Chlorination

HH FiltrationSource Improvement

HH Flocculation/Disinfection

Limitations and QualificationsLimitations and Qualifications

Limited sensitivity analysisLimited sensitivity analysis

Uncertainty (costs, effects, Uncertainty (costs, effects, population model) of any CEApopulation model) of any CEA

CEA does not address:CEA does not address:Affordability/WTPAffordability/WTP

Acceptability/UptakeAcceptability/Uptake

Potential for scaling upPotential for scaling up

Potential for cost recoveryPotential for cost recovery

Recent Research in Recent Research in Household Water Household Water

TreatmentTreatment

BioSandBioSand

(intermittent slow sand) Filter(intermittent slow sand) Filter

Traditional concrete and more Traditional concrete and more recent plastic designsrecent plastic designsIn the lab, In the lab, BSFsBSFs shown to shown to reduce faecal bacteria by 2reduce faecal bacteria by 2--3 3 logs and viruses by 1.5 to 2 logs logs and viruses by 1.5 to 2 logs and and CryptosporidiumCryptosporidium oocystsoocysts by by more than 5 logs (more than 5 logs (HijnenHijnen 2004)2004)In in the field, In in the field, BSFsBSFs achieved a achieved a mean reduction of mean reduction of E. coliE. coli of of about 2 logs (about 2 logs (StauberStauber 2006; 2006; Kaiser 2002) Kaiser 2002) 1212--month RCT among 150 month RCT among 150 households reports reductions households reports reductions in in diarrhoealdiarrhoeal disease of ~40% disease of ~40% ((StauberStauber, in preparation), in preparation)

NaDCCNaDCC

TabletsTablets

66--month placebomonth placebo--controlled RCT in Bangladesh slum controlled RCT in Bangladesh slum demonstrated consistent microbiological effectiveness, but demonstrated consistent microbiological effectiveness, but some excess dosing to variations in vessel size (Clasen 2007) some excess dosing to variations in vessel size (Clasen 2007) HealthHealth--outcome trial being completed in Ghana by CDC and outcome trial being completed in Ghana by CDC and othersothers

1

10

100

1000

10000

Baseline 1st 2nd 3rd 4thSampling Point

TTC

/100

ml (

log

10sc

ale)

ControlIntervention

Locally produced ceramic filtersLocally produced ceramic filtersTested production filters Tested production filters from Cambodia, Ghana, from Cambodia, Ghana, Nicaragua Nicaragua Under controlled Under controlled circumstances, the filters circumstances, the filters achieved up to 99.99% (4 achieved up to 99.99% (4 log) reduction in log) reduction in E. coliE. coliIn the field, filters reduced In the field, filters reduced E. coliE. coli counts by a mean counts by a mean 95.1% in treated versus 95.1% in treated versus control households (Brown control households (Brown 2007)2007)Filters were associated with Filters were associated with an estimated 46% reduction an estimated 46% reduction in diarrhoea among filter in diarrhoea among filter users versus non users (RR: users versus non users (RR: 0.54, 95% CI 0.410.54, 95% CI 0.41--0.71).0.71).

Brown J, Sobsey

M (2007). Independent Appraisal of Ceramic Water Filtration Interventions in Cambodia. New York: UNICEF

HWTS in SchoolsHWTS in Schools

Pilot project using the SWS in school in Kenya was Pilot project using the SWS in school in Kenya was associated with 44% reduction in absenteeism among associated with 44% reduction in absenteeism among students and health care savings to the school of students and health care savings to the school of US$5.49 per student (US$5.49 per student (MigeleMigele 2007)2007)SchoolSchool--based water and hygiene intervention in 9 based water and hygiene intervention in 9 schools in Kenya was associated with a significant schools in Kenya was associated with a significant increases in student knowledge of correct water increases in student knowledge of correct water treatment practices and household water treatment. treatment practices and household water treatment. Absenteeism among intervention school students fell Absenteeism among intervention school students fell 35% compared to 5% in control schools (O35% compared to 5% in control schools (O’’Reilly Reilly 2007). 2007).

Emergency Use of Emergency Use of HWTSHWTS

Public Health and the EnvironmentWater, Sanitation and Health

Scaling Up Household Water Treatment: Looking Back, Seeing Forward

Acceptability, Use, Sustainability and Acceptability, Use, Sustainability and Scaling UpScaling Up

AcknowledgementsAcknowledgements

CDC (S. CDC (S. LubyLuby, R. Quick J. Crump, T. Chiller, E. , R. Quick J. Crump, T. Chiller, E. MintzMintz))Procter & Gamble (G. Procter & Gamble (G. AllgoodAllgood, B. Keswick), B. Keswick)WHO (J. Bartram, B. Gordon, L. Haller)WHO (J. Bartram, B. Gordon, L. Haller)Johns Hopkins (D. Walker, S. Johns Hopkins (D. Walker, S. DoocyDoocy))University of Bristol (S. Gundry, J. Wright)University of Bristol (S. Gundry, J. Wright)UC Berkeley (J. UC Berkeley (J. ColfordColford))University of Wales (L. University of Wales (L. FewtrellFewtrell))University of North Carolina (M. University of North Carolina (M. SobseySobsey, J. Brown), J. Brown)LSHTM (S. LSHTM (S. CairncrossCairncross, V. Curtis, I. Roberts, T. , V. Curtis, I. Roberts, T. RabieRabie, L. Smith, W. Schmidt, S. Thomas), L. Smith, W. Schmidt, S. Thomas)