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Intervention Review

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Interventions to improve water quality for preventing diarrhoea

  1. Thomas F Clasen1,*,
  2. Ian G Roberts2,
  3. Taber Rabie3,
  4. Wolf-Peter Schmidt1,
  5. Sandy Cairncross3

Editorial Group: Cochrane Infectious Diseases Group

Published Online: 19 JUL 2006

Assessed as up-to-date: 21 JAN 2006

DOI: 10.1002/14651858.CD004794.pub2


How to Cite

Clasen TF, Roberts IG, Rabie T, Schmidt WP, Cairncross S. Interventions to improve water quality for preventing diarrhoea. Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD004794. DOI: 10.1002/14651858.CD004794.pub2.

Author Information

  1. 1

    London School of Hygiene & Tropical Medicine, Department of Infectious and Tropical Diseases, London, UK

  2. 2

    London School of Hygiene & Tropical Medicine, Cochrane Injuries Group, London, UK

  3. 3

    London School of Hygiene & Tropical Medicine, Department of Infectious and Tropical Diseases, Disease Control and Vector Biology Unit, London, UK

*Thomas F Clasen, Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. thomas.clasen@lshtm.ac.uk.

Publication History

  1. Publication Status: Edited (no change to conclusions)
  2. Published Online: 19 JUL 2006

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Characteristics of included studies [ordered by study ID]
Alam 1989

MethodsQuasi-randomized controlled trial


ParticipantsNumber: 623 children

Inclusion criteria: aged 6 to 23 months


Interventions1. Improved water supply + hygiene education (3 subunits)
2. Primary drinking supply (2 subunits)


Outcomes1. Incidence of diarrhoea among children aged 6 to 23 months by water source, hygiene practices, and household socioeconomic characteristics


NotesLocation: 5 political subunits in a village in rural Bangladesh

Length: 3 years

Publication status: journal

Austin 1993-i

MethodsRandomized controlled trial


ParticipantsNumber: 287 children

Inclusion criteria: aged 25 to 60 months (group B) from villages primarily using open, shallow wells for drinking water


Interventions1. Sodium hypochlorite solution used at household level (11 villages)
2. Primary drinking supply (11 villages)


Outcomes1. Longitudinal prevalence of diarrhoea
2. Change in nutritional status using weight-for-height Z-score


NotesLocation: 22 rural villages in The Gambia

Length: 20 weeks

Publication status: PhD dissertation

Austin 1993-ii

MethodsAs above


ParticipantsNumber: 144 children between 6 and 24 months


InterventionsAs above


OutcomesAs above


NotesAs above

Aziz 1990

MethodsQuasi-randomized controlled trial


ParticipantsNumber: about 9600 people of all ages from 1570 households


Interventions1. Improved water supply + sanitation + hygiene education
2. Primary drinking supply


Outcomes1. Longitudinal prevalence of diarrhoea:

  • portion of among children < 5 years
  • portion of episodes classified as persistent
  • percentage of days with diarrhoea
  • odds ratios of frequent diarrhoea
  • related to environmental factors


NotesLocation: 2 villages in rural Bangladesh

Length: 3 years

Publication status: journal

Chiller 2004

MethodsRandomized controlled trial


ParticipantsNumber: 3401 persons

Inclusion criteria: all ages from 514 households with at least one child under 1 year


Interventions1. Flocculant-disinfectant sachets used at household level + hygiene education
2. Primary drinking supply


Outcomes1. Longitudinal prevalence of diarrhoea (portion of total days of diarrhoea out of total days of observation) among all ages
2. Incidence of persistent diarrhoea


NotesLocation: 42 neighbourhood clusters in 12 rural villages in Guatemala

Length: 13 weeks

Publication status: unpublished

Clasen 2004b

MethodsRandomized controlled trial


Participants324 persons of all ages from 60 households


Interventions1. Household gravity water filter system using imported ceramic filter elements
2. Primary drinking supply


Outcomes1. Period prevalence of diarrhoea (7-day recall) among all ages
2. Microbial water quality


NotesLocation: rural Bolivian community

Length: 5 months

Publication status: unpublished

Clasen 2004c

MethodsRandomized controlled trial


ParticipantsNumber: 50 households with 280 persons, of which 32 (11%) were under age 5


Interventions1. Household gravity water filter system using imported ceramic filter elements
2. Primary drinking supply


Outcomes1. Period prevalence of diarrhoea (7-day recall) among householders assessed at approximately 6-week intervals


NotesLocation: rural Bolivia

Length: 6 months

Publication status: journal

Colford 2002

MethodsRandomized controlled trial


Participants236 children 12 years or older from 77 households


Interventions1. Household reverse osmosis filters
2. Primary drinking supply


Outcomes1. Incidence of watery diarrhoea
2. Gastrointestinal illness and various other symptoms
3. Water consumption
4. Effectiveness of blinding


NotesLocation: urban community in California, USA

Length: 4 months

Publication status: journal

Conroy 1996

MethodsRandomized controlled trial


Participants206 Maasai children aged 5 to 16 years in 3 adjoining areas of single province


Interventions1. Solar disinfection in plastic bottles at household level
2. Primary drinking supply


Outcomes1. Period prevalence of diarrhoea


NotesLocation: single province of rural Kenya

Length: 12 weeks

Publication status: journal

Conroy 1999

MethodsRandomized controlled trial


Participants349 Maasai children < 6 years in 140 households


Interventions1. Solar disinfection in plastic bottles at household level
2. Primary drinking supply


Outcomes1. Period prevalence of diarrhoea


NotesLocation: rural Kenya

Length: 1 year

Publication status: journal

Crump 2004-i

MethodsRandomized controlled trial


Participants6650 persons of all ages in 604 family compounds; participation limited to family compounds with at least 1 child < 2 years and likely to be using highly turbid source water


Interventions1. Sodium hypochlorite used at household level + hygiene education
2. Primary drinking supply


Outcomes1. Longitudinal prevalence (weeks with diarrhoea/weeks of observation) among all ages
2. Breastfeeding and consumption of food and water for children < 2 years
3. Deaths
4. Use of intervention
5. Mothers' knowledge of and acceptance of intervention (weeks 5 and 15)
6. Microbial water quality and turbidity
7. Mothers' knowledge of and attitudes to intervention


NotesLocation: 49 rural villages in western Kenya

Length: 20 weeks

Publication status: unpublished

Crump 2004-ii

MethodsSee Crump 2004-i


ParticipantsAs above


Interventions1. Flocculant-disinfectant sachets used at household level + hygiene
2. Primary drinking supply


OutcomesAs above


NotesAs above

Doocy 2004

MethodsRandomized controlled trial


Participants2191 persons of all ages (1138 intervention, 1053 controls), of which 735 are children < 5 (395 intervention, 340 controls) from households in settlement area not using treated water for drinking


Interventions1. Flocculant-disinfectant sachets used at household level, plus water storage vessel
2. Primary drinking supply; also received vessel


Outcomes1. Longitudinal prevalence (days with diarrhoea/total days of observation)
2. Prevalence of bloody diarrhoea
3. Utilization and acceptability data from exit survey


NotesLocation: Liberian camp for displaced persons

Length: 12 weeks

Publication status: unpublished

du Preez 2004

MethodsRandomized controlled trial


Participants115 children < 5 years


Interventions1. Household commercial ceramic filter using imported components (60 children)
2. Primary drinking supply (55 children)


Outcomes1. Incidence of diarrhoea
2. Incidence of bloody diarrhoea and non-bloody diarrhoea
3. Microbiological water quality


NotesLocation: rural South Africa and Zimbabwe

Length: 6 months

Publication status: unpublished

Garrett 2004

MethodsQuasi-randomized controlled trial


Participants960 children < 5 years


Interventions1. Household chlorination using sodium hypochlorite solution + improved water supply + sanitation + hygiene education + improved storage (618 children)
2. Primary drinking supply (342 children)


Outcomes1. Incidence of diarrhoea


NotesLocation: rural Kenya

Length: not reported

Publication status: unpublished

Gasana 2002

MethodsQuasi-randomized controlled trial


Participants150 children < 5 years (in intervention group, controls)


Interventions1. Improved source: pipes to stand post; sedimentation tank; ceramic filter; storage tank; and communal tap (95 children)
2. Primary drinking supply (55 children)


Outcomes1. Incidence of diarrhoea


NotesLocation: rural Rwanda

Length: 1 year

Publication status: journal

Handzel 1998

MethodsRandomized controlled trial


Participants447 children aged 3 to 60 months from 276 households using municipal water (household taps) as primary source of drinking water which had tested positive at baseline for Escherichia coli


Interventions1. Household chlorination using sodium hypochlorite solution, special storage vessel and hygiene instruction about why and how to treat water (140 households)
2. Primary drinking supply (136 households)


Outcomes1. Incidence of diarrhoea
2. Microbial water quality


NotesLocation: informal settlement in urban Bangladesh

Length: 8 months

Publication status: PhD dissertation

Jensen 2003

MethodsQuasi-randomized controlled trial


Participants226 children < 5 years


Interventions1. Village level chlorination of water supply using calcium hypochlorite (82 children)
2. Primary drinking supply (144 children)


Outcomes1. Incidence of diarrhoea
2. Microbial water quality


NotesLocation: 2 villages in Pakistan

Length: 6 months

Publication status: journal

Controlled for sanitation and water storage status of households, and for seasonality

Kirchhoff 1985

MethodsRandomized controlled trial


Participants112 persons (all ages) from 20 families with at least 2 children living at home and using water from pond exclusively


Interventions1. Household level chlorination with sodium hypochlorite
2. Primary drinking supply


Outcomes1. Longitudinal prevalence of diarrhoea
2. Microbial water quality
3. Acceptability of intervention to study population


NotesLocation: rural Brazil

Length: 18 weeks

Publication status: journal

Luby 2004a-i

MethodsQuasi-randomized controlled trial


Participants2365 persons < 15 years from 285 households


Interventions1. Bleach + regular vessel (640 people)
2. Primary drinking supply (1027 people)


Outcomes1. Longitudinal prevalence of diarrhoea
2. Use of intervention by certain household characteristics


NotesLocation: 3 neighbourhoods in squatter settlements in Karachi, Pakistan

Length: 6 months

Publication status: journal

Luby 2004a-ii

MethodsSee Luby 2004a-i


ParticipantsSee Luby 2004a-i


Interventions1. Bleach + insulated vessel (697 people)
2. Primary drinking supply (1027 people)


OutcomesSee Luby 2004a-i


NotesSee Luby 2004a-i

Luby 2004b-i

MethodsRandomized controlled trial


Participants5520 persons of all ages


Interventions1. Dilute bleach + vessel (1747 people)
2. Primary drinking supply (1852 people)


Outcomes1. Incidence and longitudinal prevalence of diarrhoea


NotesLocation: 47 squatter settlements of Karachi, Pakistan

Length: 8 months

Publication status: unpublished

Luby 2004b-ii

MethodsSee Luby 2004b-i


ParticipantsSee Luby 2004b-i


Interventions1. Flocculant-disinfectant + soap (1806 in flocculant-disinfection group)
2. Primary drinking supply (1852 people)


OutcomesSee Luby 2004b-i


NotesSee Luby 2004b-i

Luby 2004b-iii

MethodsSee Luby 2004b-i


ParticipantsSee Luby 2004b-i


Interventions1. Flocculant-disinfectant + vessel (1833 in flocculant-disinfection group)
2. Primary drinking supply (1852 people, 40.0%)


OutcomesSee Luby 2004b-i


NotesSee Luby 2004b-i

Lule 2005

MethodsRandomized controlled trial


Participants2201 persons of all ages among 458 households without access to chlorinated municipal water; at least 1 resident of each household was HIV+


Interventions1. Household level chlorination using sodium hypochlorite + special vessel (1097 people)
2. Primary drinking supply (1104 people)

Note: hygiene education was provided to both groups


Outcomes1. Incidence of diarrhoea
2. Days with diarrhoea (longitudinal prevalence)
3. Days lost from work or school
4. Aetiology of diarrhoea
5. Frequency of clinic visits and hospitalization
6. Mortality


NotesLocation: households in rural Uganda

Length: 5 months

Publication status: unpublished

Succeeded by 18-month Randomized controlled trial that included cotrimoxazole prophylaxis

Mahfouz 1995

MethodsQuasi-randomized controlled trial


Participants311 children < 5 years (among intervention households, among controls) among 171 families


Interventions1. Household level chlorination using calcium hypochlorite (159 children)
2. Primary drinking supply (152 children)


Outcomes1. Reported cases of diarrhoea in intervention year compared with previous year


NotesLocation: 9 villages in rural Saudi Arabia

Length: 6 months

Publication status: journal

Messou 1997

MethodsQuasi-randomized controlled trial


ParticipantsApproximately 985 to 1260 (depending on study year) children < 5 years


Interventions1. Improved water supply + sanitation + hygiene education + oral rehydration therapy for those suffering from diarrhoea (2 villages)
2. Primary drinking supply (2 villages)


Outcomes1. Incidence of diarrhoea
2. Reduction in deaths attributable to diarrhoea
3. Utilization of oral rehydration solution


NotesLocation: 4 villages in rural Ivory Coast

Length: 5 years

Publication status: journal

Quick 1999

MethodsRandomized controlled trial


Participants791 persons of all ages from 127 households


Interventions1. Household level chlorination + vessel + hygiene education (400 people, 64 households)
2. Primary drinking supply (391 people, 63 households)


Outcomes1. Mean episodes of diarrhoea per person
2. Microbiological water quality


NotesLocation: 2 peri-urban communities in Bolivia

Length: 5 months

Publication status: journal

Quick 2002

MethodsQuasi-randomized controlled trial


Participants1584 persons of all ages from 260 households


Interventions1. Household level chlorination + vessel + hygiene education (166 households)
2. Primary drinking supply (94 households)


Outcomes1. Incidence of diarrhoea
2. Microbiological water quality


NotesLocation: 2 peri-urban communities in Zambia

Length: 3 months

Publication status: journal

Reller 2003-i

MethodsRandomized controlled trial


Participants492 households each with a child < 12 months or mother in last trimester of pregnancy


Interventions1. Flocculant-disinfectant (102 households)
2. Primary drinking supply (96 households)


Outcomes1. Incidence of diarrhoea
2. Intervention knowledge and acceptability
3. Microbiological water quality
4. Intervention utilization


NotesLocation: 12 villages in rural Guatemala

Length: 12 months

Publication status: journal

Reller 2003-ii

MethodsSee Reller 2003-i


ParticipantsSee Reller 2003-i


Interventions1. Bleach only (97 households)
2. Primary drinking supply (as above)


OutcomesSee Reller 2003-i


NotesSee Reller 2003-i

Reller 2003-iii

MethodsSee Reller 2003-i


ParticipantsSee Reller 2003-i


Interventions1. Bleach + vessel (97 households)
2. Primary drinking supply (as above)


OutcomesSee Reller 2003-i


NotesSee Reller 2003-i

Reller 2003-iv

MethodsSee Reller 2003-i


ParticipantsSee Reller 2003-i


Interventions1. Flocculant-disinfectant + vessel (100 households)
2. Primary drinking supply (as above)


OutcomesSee Reller 2003-i


NotesSee Reller 2003-i

Roberts 2001

MethodsRandomized controlled trial


Participants1160 persons of all ages; of these, 208 were children < 5 years


Interventions1. Improved storage: bucket with spout and narrow opening to limit hand entry (310 people including 51 children, 100 households)
2. Primary drinking supply (850 people including 157 children, 300 households)


Outcomes1. Incidence of diarrhoea
2. Microbiological water quality
3. Incidence of diarrhoea by selected environmental factors


NotesLocation: Malawi refugee camp

Length: 4 months

Publication status: journal

Semenza 1998

MethodsRandomized controlled trial


Participants1583 persons of all ages from 240 households, half with access to piped water (first control group) and half without (of which 62 received intervention, and 58 served as a second control group); these included 344 children < 5 (176 from piped water households, 88 intervention and 80 no-chlorination)


Interventions1. Household level chlorination + vessel + hygiene education
2. Primary drinking supply


Outcomes1. Incidence of diarrhoea
2. Incidence of diarrhoea by selected household and water management practices


NotesLocation: urban Uzbekistan

Length: 9.5 weeks

Publication status: journal

Torun 1982

MethodsQuasi-randomized controlled trial


Participants2103 persons of all ages from 2 villages


Interventions1. Source protection (spring), chlorination facilities, "adequate storage", and water mains with faucets to yards of intervention village (1006 people)
2. Primary drinking supply (1097 people)


Outcomes1. Incidence of diarrhoea


NotesLocation: 2 small villages in Guatemala

Length: 12 months

Publication status: book

URL 1995-i

MethodsRandomized controlled trial


Participants1120 children < 5 years (265 and 289 allocated to the water quality intervention arms, 297 to an education only arm, and 269 to the control arm) from 680 families from three demographic regions


Interventions1. Locally fabricated ceramic filters (265 children or 23.6%)
2. Primary drinking supply (269 children)


Outcomes1. Incidence of diarrhoea
2. Nutritional status (weight/age)


NotesLocation: 3 demographic regions of Guatemala

Length: 12 months

Publication status: unpublished

URL 1995-ii

MethodsSee URL 1995-i


ParticipantsSee URL 1995-i


Interventions1. Locally fabricated ceramic filters + hygiene education
2. Primary drinking supply (as above)


OutcomesSee URL 1995-i


NotesSee URL 1995-i

Xiao 1997

MethodsQuasi-randomized controlled trial


Participants4649 persons of all ages


Interventions1. Improved water supply + sanitation + hygiene education (2363 people)
2. Primary drinking supply (2286 people)


Outcomes1. Incidence of diarrhoea


NotesLocation: 2 villages in rural China

Length: 3 years

Publication status: journal

 
Characteristics of excluded studies [ordered by study ID]

StudyReason for exclusion

Asaolu 2002Study not RCT or quasi-RCT; outcome measures not include diarrhoea

Azurin 1974Outcome measures not include diarrhoea

Bahl 1976Study not RCT or quasi-RCT

Bersh 1985Study not RCT or quasi-RCT

Chongsuvivatwong 94Study not RCT or quasi-RCT

Colwell 2003Outcome measures not include diarrhoea

Conroy 2001Outcome measures not include diarrhoea

Deb 1986Outcome measures not include diarrhoea

Esrey 1991bStudy not RCT or quasi-RCT

Fewtrell 1994Study not RCT or quasi-RCT; outcome measures not include diarrhoea

Fewtrell 1997Study not RCT or quasi-RCT; outcome measures not include diarrhoea

Ghannoum 1981Study not RCT or quasi-RCT; outcome measures not include diarrhoea

Hellard 2001Outcome measures not include diarrhoea

Hoque 1996Study not RCT or quasi-RCT

Iijima 2001Study not RCT or quasi-RCT

Jensen 2002Outcome measures not include diarrhoea

Khan 1984Outcome measures not include diarrhoea

Macy 1998Study not RCT or quasi-RCT; intervention not an improvement in water quality; outcome measures not include diarrhoea

Maeusezahl 2003Study not RCT or quasi-RCT

McCabe 1957Intervention not an improvement in water quality

Mertens 1990Study not RCT or quasi-RCT; intervention not an improvement in water quality; outcome measures not include diarrhoea

Nanan 2003Study not RCT or quasi-RCT

Payment 1991aStudy not RCT or quasi-RCT
Outcome measures not include diarrhoea

Payment 1991bOutcome measures not include diarrhoea

Pinfold 1990Intervention not an improvement in water quality; outcome measures not include diarrhoea

Rubenstein 1969Study not RCT or quasi-RCT

Sathe 1996Study not RCT or quasi-RCT

Shiffman 1978Study not RCT or quasi-RCT

Shum 1971Study not RCT or quasi-RCT; intervention not an improvement in water quality; outcome measures not include diarrhoea

Sorvillo 1994Outcome measures not include diarrhoea

Tonglet 1992Study not RCT or quasi-RCT

Trivedi 1971Study not RCT or quasi-RCT

VanDerslice 1995Study not RCT or quasi-RCT; intervention not an improvement in water quality

Varghese 2002Study not RCT or quasi-RCT

 
Characteristics of studies awaiting assessment [ordered by study ID]
Clasen 2005

Methods

Participants

Interventions

Outcomes

Notes

Colford 2005a

Methods

Participants

Interventions

Outcomes

Notes

Colford 2005b

Methods

Participants

Interventions

Outcomes

Notes

Rose 2006

Methods

Participants

Interventions

Outcomes

Notes

 
Comparison 1. Water quality intervention versus control: point and type of intervention (rate ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages10Rate ratio (Random, 95% CI)Subtotals only

    1.1 Source or household treatment
10Rate ratio (Random, 95% CI)0.73 [0.63, 0.85]

    1.2 Source treatment
4Rate ratio (Random, 95% CI)0.87 [0.74, 1.02]

    1.3 Household treatment
6Rate ratio (Random, 95% CI)0.56 [0.42, 0.74]

    1.4 Household treatment: chlorination
4Rate ratio (Random, 95% CI)0.61 [0.46, 0.81]

    1.5 Household treatment: filtration
2Rate ratio (Random, 95% CI)0.37 [0.15, 0.92]

 2 Diarrhoea: children < 5 years6Rate ratio (Random, 95% CI)Subtotals only

    2.1 Source or household treatment
6Rate ratio (Random, 95% CI)0.78 [0.65, 0.94]

    2.2 Source treatment
3Rate ratio (Random, 95% CI)0.93 [0.82, 1.05]

    2.3 Household treatment
3Rate ratio (Random, 95% CI)0.42 [0.19, 0.95]

    2.4 Household treatment: chlorination
2Rate ratio (Random, 95% CI)0.53 [0.23, 1.23]

    2.5 Household treatment: filtration
1Rate ratio (Random, 95% CI)0.21 [0.07, 0.61]

 
Comparison 2. Water quality intervention versus control: point of intervention (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages7Risk ratio (Random, 95% CI)Subtotals only

    1.1 Source or household treatment
7Risk ratio (Random, 95% CI)0.45 [0.33, 0.62]

    1.2 Source treatment
1Risk ratio (Random, 95% CI)0.45 [0.43, 0.47]

    1.3 Household treatment
6Risk ratio (Random, 95% CI)0.43 [0.27, 0.70]

    1.4 Household treatment: chlorination
3Risk ratio (Random, 95% CI)0.34 [0.17, 0.68]

    1.5 Household treatment: filtration
2Risk ratio (Random, 95% CI)0.41 [0.21, 0.79]

    1.6 Household treatment: improved storage
1Risk ratio (Random, 95% CI)0.79 [0.61, 1.03]

 2 Diarrhoea: children < 5 years5Risk ratio (Random, 95% CI)Subtotals only

    2.1 Source or household treatment
5Risk ratio (Random, 95% CI)0.54 [0.43, 0.69]

    2.2 Household treatment
5Risk ratio (Random, 95% CI)0.54 [0.43, 0.69]

    2.3 Household treatment: chlorination
2Risk ratio (Random, 95% CI)0.48 [0.33, 0.68]

    2.4 Household treatment: filtration
2Risk ratio (Random, 95% CI)0.41 [0.21, 0.79]

    2.5 Household treatment: improved storage
1Risk ratio (Random, 95% CI)0.69 [0.47, 1.01]

 
Comparison 3. Water quality intervention versus control: point and type of intervention (longitudinal prevalence ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages11Long. prev. ratio (Random, 95% CI)Subtotals only

    1.1 Source or household treatment
11Long. prev. ratio (Random, 95% CI)0.56 [0.27, 1.16]

    1.2 Source treatment
1Long. prev. ratio (Random, 95% CI)0.56 [0.37, 0.84]

    1.3 Household treatment
10Long. prev. ratio (Random, 95% CI)0.56 [0.25, 1.23]

    1.4 Household treatment: chlorination
5Long. prev. ratio (Random, 95% CI)0.82 [0.60, 1.11]

    1.5 Household treatment: flocculation and disinfection
5Long. prev. ratio (Random, 95% CI)0.40 [0.14, 1.16]

 2 Diarrhoea: children < 5 years12Long. prev. ratio (Random, 95% CI)Subtotals only

    2.1 Source or household treatment
11Long. prev. ratio (Random, 95% CI)0.61 [0.29, 1.26]

    2.2 Source treatment
1Long. prev. ratio (Random, 95% CI)0.63 [0.49, 0.81]

    2.3 Household treatment
10Long. prev. ratio (Random, 95% CI)0.60 [0.27, 1.36]

    2.4 Household treatment: chlorination
5Long. prev. ratio (Random, 95% CI)0.91 [0.82, 1.02]

    2.5 Household treatment: flocculation and disinfection
5Long. prev. ratio (Random, 95% CI)0.42 [0.13, 1.37]

 
Comparison 4. Water quality intervention versus control: point and type of intervention (odds ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages9Odds ratio (Random, 95% CI)Subtotals only

    1.1 Source or household treatment
9Odds ratio (Random, 95% CI)0.68 [0.59, 0.79]

    1.2 Household treatment
9Odds ratio (Random, 95% CI)0.68 [0.59, 0.79]

    1.3 Household treatment: chlorination
3Odds ratio (Random, 95% CI)0.77 [0.58, 1.02]

    1.4 Household treatment: filtration
2Odds ratio (Random, 95% CI)0.35 [0.23, 0.53]

    1.5 Household treatment: solar disinfection
2Odds ratio (Random, 95% CI)0.69 [0.63, 0.74]

    1.6 Household treatment: flocculation and disinfection
2Odds ratio (Random, 95% CI)0.77 [0.65, 0.90]

 2 Diarrhoea: children < 5 years6Odds ratio (Random, 95% CI)Subtotals only

    2.1 Source or household treatment
6Odds ratio (Random, 95% CI)0.70 [0.50, 0.99]

    2.2 Household treatment
6Odds ratio (Random, 95% CI)0.70 [0.50, 0.99]

    2.3 Household treatment: chlorination
2Odds ratio (Random, 95% CI)0.90 [0.65, 1.25]

    2.4 Household treatment: filtration
2Odds ratio (Random, 95% CI)0.32 [0.11, 0.90]

    2.5 Household treatment: flocculation and disinfection
2Odds ratio (Random, 95% CI)0.86 [0.57, 1.29]

 
Comparison 5. Water quality intervention versus control: point and type of intervention (means ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages1Means ratio (Random, 95% CI)Totals not selected

    1.1 Source or household treatment
1Means ratio (Random, 95% CI)Not estimable

    1.2 Household treatment
1Means ratio (Random, 95% CI)Not estimable

    1.3 Household treatment: chlorination
1Means ratio (Random, 95% CI)Not estimable

 2 Diarrhoea: children < 5 years1Means ratio (Random, 95% CI)Totals not selected

    2.1 Source or household treatment
1Means ratio (Random, 95% CI)Not estimable

    2.2 Household treatment
1Means ratio (Random, 95% CI)Not estimable

    2.3 Household treatment: chlorination
1Means ratio (Random, 95% CI)Not estimable

 
Comparison 6. Water quantity intervention versus control: by compliance with intervention (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages4Risk ratio (Random, 95% CI)Subtotals only

    1.1 < 50%
1Risk ratio (Random, 95% CI)0.44 [0.28, 0.69]

    1.2 50% or >
3Risk ratio (Random, 95% CI)0.28 [0.14, 0.57]

 
Comparison 7. Water quality intervention versus control: by compliance with intervention (odds ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages7Odds ratio (Random, 95% CI)Subtotals only

    1.1 < 50%
4Odds ratio (Random, 95% CI)0.80 [0.71, 0.89]

    1.2 50% or >
3Odds ratio (Random, 95% CI)0.40 [0.28, 0.57]

 
Comparison 8. Water quality intervention versus control: by ambient water quality (rate ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages4Rate ratio (Random, 95% CI)Subtotals only

    1.1 0 colony-forming units (CFU)
1Rate ratio (Random, 95% CI)0.54 [0.28, 1.06]

    1.2 10 to 99 CFU
3Rate ratio (Random, 95% CI)0.79 [0.65, 0.95]

 
Comparison 9. Water quality intervention versus control: by ambient water quality (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages4Risk ratio (Random, 95% CI)Subtotals only

    1.1 10 to 99 colony-forming units (CFU)
2Risk ratio (Random, 95% CI)0.36 [0.07, 1.81]

    1.2 > 99 CFU
2Risk ratio (Random, 95% CI)0.41 [0.21, 0.79]

 
Comparison 10. Water quality intervention versus control: by ambient water quality (longitudinal prevalence ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages5Long. prev. ratio (Random, 95% CI)Subtotals only

    1.1 10 to 99 colony-forming units (CFU)
2Long. prev. ratio (Random, 95% CI)0.80 [0.69, 0.93]

    1.2 > 99 CFU
3Long. prev. ratio (Random, 95% CI)1.07 [0.88, 1.29]

 
Comparison 11. Water quality intervention versus control: by ambient water quality (odds ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages22Odds ratio (Random, 95% CI)Subtotals only

    1.1 0 colony-forming units (CFU)
1Odds ratio (Random, 95% CI)0.54 [0.28, 1.06]

    1.2 10 to 99 CFU
14Odds ratio (Random, 95% CI)0.70 [0.60, 0.80]

    1.3 > 99 CFU
7Odds ratio (Random, 95% CI)0.69 [0.49, 0.96]

 
Comparison 12. Water quality intervention versus control: by sufficiency of water quantity (long. prev. ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages5Long. prev. ratio (Random, 95% CI)Subtotals only

    1.1 Sufficient
1Long. prev. ratio (Random, 95% CI)0.62 [0.47, 0.82]

    1.2 Insufficient
4Long. prev. ratio (Random, 95% CI)0.53 [0.15, 1.96]

 
Comparison 13. Water quality intervention versus control: by water supply level (rate ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages9Rate ratio (Random, 95% CI)Subtotals only

    1.1 Improved water supply
3Rate ratio (Random, 95% CI)0.75 [0.56, 1.00]

    1.2 Unimproved water supply
6Rate ratio (Random, 95% CI)0.75 [0.63, 0.89]

 
Comparison 14. Water quality intervention versus control: by water supply level (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages6Risk ratio (Random, 95% CI)Subtotals only

    1.1 Improved water supply
3Risk ratio (Random, 95% CI)0.60 [0.36, 0.99]

    1.2 Unimproved water supply
3Risk ratio (Random, 95% CI)0.36 [0.20, 0.64]

 
Comparison 15. Water quality intervention versus control: by water supply level (longitudinal prevalence ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages11Long. prev. ratio (Random, 95% CI)Subtotals only

    1.1 Improved water supply
4Long. prev. ratio (Random, 95% CI)0.39 [0.28, 0.55]

    1.2 Unimproved water supply
7Long. prev. ratio (Random, 95% CI)0.62 [0.23, 1.67]

 
Comparison 16. Water quality intervention versus control: by water supply level (odds ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages9Odds ratio (Random, 95% CI)Subtotals only

    1.1 Improved water supply
1Odds ratio (Random, 95% CI)0.47 [0.24, 0.92]

    1.2 Unimproved water supply
8Odds ratio (Random, 95% CI)0.69 [0.59, 0.80]

 
Comparison 17. Water quality intervention versus control: by sanitation level (rate ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages7Rate ratio (Random, 95% CI)Subtotals only

    1.1 Improved sanitation
4Rate ratio (Random, 95% CI)0.56 [0.38, 0.83]

    1.2 Unimproved sanitation
3Rate ratio (Random, 95% CI)0.80 [0.64, 1.00]

 
Comparison 18. Water quality intervention versus control: by sanitation level (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages4Risk ratio (Random, 95% CI)Subtotals only

    1.1 Improved sanitation
3Risk ratio (Random, 95% CI)0.48 [0.31, 0.75]

    1.2 Unimproved sanitation
1Risk ratio (Random, 95% CI)0.44 [0.28, 0.69]

 
Comparison 19. Water quality intervention versus control: by sanitation level (longitudinal prevalence ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages7Long. prev. ratio (Random, 95% CI)Subtotals only

    1.1 Improved sanitation
4Long. prev. ratio (Random, 95% CI)0.39 [0.28, 0.55]

    1.2 Unimproved sanitation
3Long. prev. ratio (Random, 95% CI)0.43 [0.09, 2.09]

 
Comparison 20. Water quality intervention versus control: simple and compound interventions (rate ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages10Risk ratio (Random, 95% CI)Subtotals only

    1.1 Water quality only
3Risk ratio (Random, 95% CI)0.55 [0.26, 1.17]

    1.2 Water quality + hygiene promotion
3Risk ratio (Random, 95% CI)0.85 [0.70, 1.03]

    1.3 Water quality + vessel
4Risk ratio (Random, 95% CI)0.61 [0.46, 0.81]

    1.4 Water quality + sanitation
1Risk ratio (Random, 95% CI)0.75 [0.70, 0.80]

    1.5 Water quality + improved water supply
2Risk ratio (Random, 95% CI)0.77 [0.71, 0.84]

 
Comparison 21. Water quality intervention versus control: simple and compound interventions (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages6Risk ratio (Random, 95% CI)Subtotals only

    1.1 Water quality only
2Risk ratio (Random, 95% CI)0.52 [0.32, 0.86]

    1.2 Water quality + hygiene promotion
3Risk ratio (Random, 95% CI)0.29 [0.14, 0.59]

    1.3 Water quality + vessel
2Risk ratio (Random, 95% CI)0.36 [0.07, 1.81]

    1.4 Water quality + sanitation
1Risk ratio (Random, 95% CI)0.44 [0.28, 0.69]

    1.5 Water quality + improved water supply
1Risk ratio (Random, 95% CI)0.44 [0.28, 0.69]

 
Comparison 22. Water quality intervention versus control: simple and compound interventions (longitudinal prevalence ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages11Long. prev. ratio (Random, 95% CI)Subtotals only

    1.1 Water quality only
3Long. prev. ratio (Random, 95% CI)1.07 [0.88, 1.29]

    1.2 Water quality + hygiene promotion
4Long. prev. ratio (Random, 95% CI)0.71 [0.59, 0.86]

    1.3 Water quality + vessel
3Long. prev. ratio (Random, 95% CI)0.26 [0.10, 0.69]

    1.4 Water quality + sanitation
1Long. prev. ratio (Random, 95% CI)0.56 [0.37, 0.84]

    1.5 Water quality + improved water supply
1Long. prev. ratio (Random, 95% CI)0.56 [0.37, 0.84]

 
Comparison 23. Water quality intervention versus control: simple and compound interventions (odds ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: all ages13Odds ratio (Random, 95% CI)Subtotals only

    1.1 Water quality only
6Odds ratio (Random, 95% CI)0.64 [0.53, 0.77]

    1.2 Water quality + hygiene promotion
1Odds ratio (Random, 95% CI)0.52 [0.30, 0.90]

    1.3 Water quality + vessel
3Odds ratio (Random, 95% CI)0.77 [0.58, 1.03]

    1.4 Water quality + sanitation
3Odds ratio (Random, 95% CI)0.60 [0.43, 0.84]

    1.5 Water quality + improved water supply
4Odds ratio (Random, 95% CI)0.70 [0.59, 0.84]

 
Comparison 24. Water quality intervention versus control for RCTs: by methodological quality (rate ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: by allocation sequence4Rate ratio (Random, 95% CI)Subtotals only

    1.1 Adequate
2Rate ratio (Random, 95% CI)0.37 [0.15, 0.92]

    1.2 Unclear
2Rate ratio (Random, 95% CI)0.73 [0.61, 0.87]

 2 Diarrhoea: by allocation concealment8Rate ratio (Random, 95% CI)Subtotals only

    2.1 Adequate
4Rate ratio (Random, 95% CI)0.65 [0.49, 0.86]

    2.2 Inadequate
4Rate ratio (Random, 95% CI)0.79 [0.63, 0.99]

 3 Diarrhoea: by follow up18Rate ratio (Random, 95% CI)Subtotals only

    3.1 Adequate
4Rate ratio (Random, 95% CI)0.65 [0.49, 0.86]

    3.2 Unclear
3Rate ratio (Random, 95% CI)0.28 [0.14, 0.57]

    3.3 Inadequate
11Rate ratio (Random, 95% CI)0.81 [0.73, 0.89]

 4 Diarrhoea: by blinding4Rate ratio (Random, 95% CI)Subtotals only

    4.1 Double blind
1Rate ratio (Random, 95% CI)0.54 [0.28, 1.06]

    4.2 Open
3Rate ratio (Random, 95% CI)0.66 [0.47, 0.92]

 
Comparison 25. Water quality intervention versus control for RCTs: by methodological quality (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: by allocation sequence4Risk ratio (Random, 95% CI)Subtotals only

    1.1 Adequate
3Risk ratio (Random, 95% CI)0.28 [0.14, 0.57]

    1.2 Inadequate
1Risk ratio (Random, 95% CI)0.79 [0.61, 1.03]

 2 Diarrhoea: by allocation concealment4Risk ratio (Random, 95% CI)Subtotals only

    2.1 Adequate
3Risk ratio (Random, 95% CI)0.28 [0.14, 0.57]

    2.2 Inadequate
1Risk ratio (Random, 95% CI)0.79 [0.61, 1.03]

 3 Diarrhoea: by follow up4Risk ratio (Random, 95% CI)Subtotals only

    3.1 Unclear
3Risk ratio (Random, 95% CI)0.28 [0.14, 0.57]

    3.2 Inadequate
1Risk ratio (Random, 95% CI)0.79 [0.61, 1.03]

 4 Diarrhoea: by blinding4Risk ratio (Random, 95% CI)Subtotals only

    4.1 Open
4Risk ratio (Random, 95% CI)0.39 [0.17, 0.90]

 
Comparison 26. Water quality intervention versus control for RCTs: by methodological quality (longitudinal prevalence ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: allocation sequence10Long. prev. ratio (Random, 95% CI)Subtotals only

    1.1 Adequate
9Long. prev. ratio (Random, 95% CI)0.51 [0.23, 1.14]

    1.2 Inadequate
1Long. prev. ratio (Random, 95% CI)1.07 [0.88, 1.30]

 2 Diarrhoea: by allocation concealment10Long. prev. ratio (Random, 95% CI)Subtotals only

    2.1 Adequate
9Long. prev. ratio (Random, 95% CI)0.51 [0.23, 1.14]

    2.2 Inadequate
1Long. prev. ratio (Random, 95% CI)1.07 [0.88, 1.30]

 3 Diarrhoea: by follow up9Long. prev. ratio (Random, 95% CI)Subtotals only

    3.1 Adequate
4Long. prev. ratio (Random, 95% CI)0.54 [0.43, 0.67]

    3.2 Inadequate
5Long. prev. ratio (Random, 95% CI)0.89 [0.76, 1.04]

 4 Diarrhoea: by blinding10Long. prev. ratio (Random, 95% CI)Subtotals only

    4.1 Double blind
3Long. prev. ratio (Random, 95% CI)1.07 [0.88, 1.29]

    4.2 Open
7Long. prev. ratio (Random, 95% CI)0.45 [0.18, 1.08]

 
Comparison 27. Water quality intervention versus control for RCTs: by methodological quality (odds ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: by allocation sequence9Odds ratio (Random, 95% CI)Subtotals only

    1.1 Adequate
7Odds ratio (Random, 95% CI)0.66 [0.52, 0.83]

    1.2 Inadequate
2Odds ratio (Random, 95% CI)0.69 [0.63, 0.74]

 2 Diarrhoea: by allocation concealment9Odds ratio (Random, 95% CI)Subtotals only

    2.1 Adequate
7Odds ratio (Random, 95% CI)0.66 [0.52, 0.83]

    2.2 Inadequate
2Odds ratio (Random, 95% CI)0.69 [0.63, 0.74]

 3 Diarrhoea: by follow up9Odds ratio (Random, 95% CI)Subtotals only

    3.1 Adequate
4Odds ratio (Random, 95% CI)0.48 [0.32, 0.71]

    3.2 Inadequate
5Odds ratio (Random, 95% CI)0.75 [0.68, 0.84]

 4 Diarrhoea: by blinding9Odds ratio (Random, 95% CI)Subtotals only

    4.1 Open
9Odds ratio (Random, 95% CI)0.68 [0.59, 0.79]

 
Comparison 28. Water quality intervention versus control for quasi-RCTs: by methodological quality (rate ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: by comparability of characteristics6Rate ratio (Random, 95% CI)Subtotals only

    1.1 Adequate
4Rate ratio (Random, 95% CI)0.67 [0.54, 0.83]

    1.2 Unclear
1Rate ratio (Random, 95% CI)1.0 [0.89, 1.12]

    1.3 Inadequate
1Rate ratio (Random, 95% CI)0.94 [0.73, 1.21]

 2 Diarrhoea: by contemporaneous of data collection11Rate ratio (Random, 95% CI)Subtotals only

    2.1 Adequate
10Rate ratio (Random, 95% CI)0.59 [0.46, 0.75]

    2.2 Unclear
1Rate ratio (Random, 95% CI)1.0 [0.89, 1.12]

 
Comparison 29. Water quality intervention versus control for quasi-RCTs: by methodological quality (risk ratios)

Outcome or subgroup titleNo. of studiesNo. of participantsStatistical methodEffect size

 1 Diarrhoea: by comparability of characteristics3Risk ratio (Random, 95% CI)Subtotals only

    1.1 Adequate
2Risk ratio (Random, 95% CI)0.45 [0.43, 0.47]

    1.2 Inadequate
1Risk ratio (Random, 95% CI)0.44 [0.28, 0.69]

 2 Diarrhoea: by contemporaneous of data collection11Risk ratio (Random, 95% CI)Subtotals only

    2.1 Adequate
10Risk ratio (Random, 95% CI)0.59 [0.46, 0.75]

    2.2 Unclear
1Risk ratio (Random, 95% CI)1.0 [0.89, 1.12]