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Cited by 377Child Nutrition and Water AccessViral gastroenteritis research and epidemiologyWater Resource Management and Quality

Effectiveness of interventions to improve drinking water, sanitation, and handwashing with soap on risk of diarrhoeal disease in children in low-income and middle-income settings: a systematic review and meta-analysis

Open access
Wolf, Jennyfer, Hubbard, Sydney, Brauer, Michael, Ambelu, Argaw, Arnold, Benjamin F, Bain, Robert, Bauza, Valerie, Brown, Joe +13 more·2022·The Lancet
DOI 10.1016/s0140-6736(22)00937-0PMC PMC9251635
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Abstract

BACKGROUND: Estimates of the effectiveness of water, sanitation, and hygiene (WASH) interventions that provide high levels of service on childhood diarrhoea are scarce. We aimed to provide up-to-date estimates on the burden of disease attributable to WASH and on the effects of different types of WASH interventions on childhood diarrhoea in low-income and middle-income countries (LMICs). METHODS: In this systematic review and meta-analysis, we updated previous reviews following their search strategy by searching MEDLINE, Embase, Scopus, Cochrane Library, and BIOSIS Citation Index for studies of basic WASH interventions and of WASH interventions providing a high level of service, published between Jan 1, 2016, and May 25, 2021. We included randomised and non-randomised controlled trials conducted at household or community level that matched exposure categories of the so-called service ladder approach of the Sustainable Development Goal (SDG) for WASH. Two reviewers independently extracted study-level data and assessed risk of bias using a modified Newcastle-Ottawa Scale and certainty of evidence using a modified Grading of Recommendations, Assessment, Development, and Evaluation approach. We analysed extracted relative risks (RRs) and 95% CIs using random-effects meta-analyses and meta-regression models. This study is registered with PROSPERO, CRD42016043164. FINDINGS: 19 837 records were identified from the search, of which 124 studies were included, providing 83 water (62 616 children), 20 sanitation (40 799 children), and 41 hygiene (98 416 children) comparisons. Compared with untreated water from an unimproved source, risk of diarrhoea was reduced by up to 50% with water treated at point of use (POU): filtration (n=23 studies; RR 0·50 [95% CI 0·41-0·60]), solar treatment (n=13; 0·63 [0·50-0·80]), and chlorination (n=25; 0·66 [0·56-0·77]). Compared with an unimproved source, provision of an improved drinking water supply on premises with higher water quality reduced diarrhoea risk by 52% (n=2; 0·48 [0·26-0·87]). Overall, sanitation interventions reduced diarrhoea risk by 24% (0·76 [0·61-0·94]). Compared with unimproved sanitation, providing sewer connection reduced diarrhoea risk by 47% (n=5; 0·53 [0·30-0·93]). Promotion of handwashing with soap reduced diarrhoea risk by 30% (0·70 [0·64-0·76]). INTERPRETATION: WASH interventions reduced risk of diarrhoea in children in LMICs. Interventions supplying either water filtered at POU, higher water quality from an improved source on premises, or basic sanitation services with sewer connection were associated with increased reductions. Our results support higher service levels called for under SDG 6. Notably, no studies evaluated interventions that delivered access to safely managed WASH services, the level of service to which universal coverage by 2030 is committed under the SDG. FUNDING: WHO, Foreign, Commonwealth & Development Office, and National Institute of Environmental Health Sciences.

AI snapshot

Written from the paper’s full text.

TL;DR

This systematic review and meta-analysis found that water, sanitation, and hygiene interventions reduced childhood diarrhoea risk in low-income and middle-income countries, with larger reductions for point-of-use filtration, higher-quality water on premises, and sewer connection. No included study delivered safely managed WASH services.

Key findings

  • Across 124 studies, there were 83 water comparisons (62,616 children), 20 sanitation comparisons (40,799 children), and 41 hygiene comparisons (98,416 children). Compared with untreated water from an unimproved source, diarrhoea risk was reduced by point-of-use filtration (n=23; RR 0·50 [95% CI 0·41–0·60]), solar treatment (n=13; 0·63 [0·50–0·80]), and chlorination (n=25; 0·66 [0·56–0·77]); improved drinking water on premises with higher water quality reduced risk by 52% (n=2; 0·48 [0·26–0·87]).
  • Overall sanitation interventions reduced diarrhoea risk by 24% (RR 0·76 [95% CI 0·61–0·94]); compared with unimproved or limited sanitation, sewer connection reduced risk by 47% (n=5; 0·53 [0·30–0·93]) and basic sanitation without sewer connection by 21% (0·79 [0·61–1·03]).
  • Promotion of handwashing with soap reduced diarrhoea risk by 30% (RR 0·70 [95% CI 0·64–0·76]).
  • No studies evaluated interventions delivering safely managed WASH services, and only five (4%) of 124 included studies reported results by sex.

Methods

  • The authors updated previous reviews by searching MEDLINE, Embase, Scopus, Cochrane Library, and BIOSIS Citation Index for studies published between Jan 1, 2016, and May 25, 2021, covering literature from Jan 1, 1970, with prior reviews; eligible designs were randomised and non-randomised controlled trials at household or community level matching SDG WASH service-ladder exposure categories.
  • Two reviewers independently extracted study-level data and assessed risk of bias using a modified Newcastle-Ottawa Scale and certainty of evidence using a modified GRADE approach.
  • They analysed extracted relative risks and 95% CIs using random-effects meta-analyses and meta-regression models in Stata version 14.2; the study is registered with PROSPERO, CRD42016043164.

Limitations

  • The paper states that it did not systematically search grey literature, and notes potential exposure misclassification, low compliance, response bias, high heterogeneity across studies, limitations related to study-level analysis, and possible confounding because WASH components and intervention approaches depend on study context.
  • The paper states that evidence certainty ranged from moderate to very low, mainly because of non-randomised study designs, risk of bias, and imprecision; it also notes that GRADE was developed for health-care interventions and that complex public health interventions such as WASH are difficult to randomise or mask.
  • Evident from the text: no studies delivered safely managed WASH services; evidence for higher-level services was scarce (e.g., only two studies for improved on-premises higher water quality, one for continuous supply, and five sewer-connection studies), and sex-disaggregated reporting was available in only five of 124 studies.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1016/s0140-6736(22)00937-0

Cites

97 of 97 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 71 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    Compared with untreated water from an unimproved source, POU chlorination reduced diarrhoea risk (n=25; RR 0.66 [95% CI 0.56-0.77]).

    “and chlorination (n=25; 0·66 [0·56–0·77]; table 1)”
    Quote in the paperSubstantial claim
  • Findingown data

    No effect was found for other covariates (p>0.10).

    “No effect was found for other covariates (p>0·10; appendix 2 pp 13–14).”
    Quote in the paperNot a substantial claim
  • Findingnone given

    Although a substantial body of evidence is available from interventions of basic WASH services, evidence from interventions providing higher levels of WASH services remains scarce.

    “Although a substantial body of evidence is available from interventions of basic WASH services (eg, simple improved drinking water or sanitation, or point-of-use drinking water treatment), evidence from interventions providing higher levels of WASH services remains scarce.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: Previous analyses have often not considered intervention types extending beyond basic WASH services, such as drinking water delivered on premises, of high quality, or continuously available, or sanitation that safely disposes excreta or removes and safely treats it offsite.
  • Findingown data

    Compared with untreated water from an unimproved source, diarrhoea risk was reduced by 52% (n=2; RR 0.48 [95% CI 0.26-0.87]) with provision of an improved drinking water supply on premises with higher water quality.

    “Compared with untreated water from an unimproved source, diarrhoea risk was reduced by 52% (n=2; 0·48 [0·26–0·87]) with provision of an improved drinking water supply on premises with higher water quality”
    Quote in the paperSubstantial claim
  • Findingown data

    The meta-regression model explained 17% of the between-study variance of sanitation studies.

    “The meta-regression model explained 17% of the between-study variance of sanitation studies.”
    Quote in the paperNot a substantial claim
  • May combine two claims. 36
  • Classified as probably not a substantial claim. 33

  • May combine two claims.

    Findingown data

    Improved sanitation (p=0.35) and rural setting (p=0.37) were not associated with risk of diarrhoeal disease.

    “Further examined covariates, including improved sanitation (p=0·35) and rural setting (p=0·37), were not associated with risk of diarrhoeal disease; appendix 2 p 13).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The total study population included 62,616 children in the drinking water analysis, 40,799 children in the sanitation analysis, and 98,416 children in the hygiene analysis.

    “The total study population included 62 616 children in the drinking water analysis, 40 799 children in the sanitation analysis, and 98 416 children in the hygiene analysis.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The meta-regression model explained 11% of the between-study variance of drinking water studies.

    “The meta-regression model explained 11% of the between-study variance of drinking water studies.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    21,290 records were identified from the search, of which 15,634 were screened and 83 assessed for eligibility.

    “21 290 records were identified from the search, of which 15 634 were screened and 83 assessed for eligibility (figure 3).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    23 new studies were added to the previous meta-analyses, including 12 new comparisons for the water analysis, seven for the sanitation analysis, and ten for the hygiene analysis.

    “23 new studies were added to the previous meta-analyses, including 12 new comparisons for the water analysis, seven for the sanitation analysis, and ten for the hygiene analysis.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    This systematic review contains evidence from 124 WASH interventions.

    “This systematic review contains evidence from 124 WASH interventions.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Only four studies of drinking water reported results by sex; thus, the estimates are not disaggregated by sex.

    “Only four studies of drinking water (three POU filter studies36, 37, 38 and one POU chlorine study39) reported results by sex; thus, our estimates are not disaggregated by sex (appendix 1 pp 5–7).”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [36] Aiken BA Stauber CE Ortiz GM Sobsey MD An assessment of continued use and health impact of the concrete biosand filter in Bonao, Dominican Republic Am J Trop Med Hyg 85 2011 309 317 21813853 PMC3144831 source

      Not checked in the free run.

    • cites [37] Brown J Improving household drinking water quality: use of ceramic water filters in Cambodia https://www.wsp.org/sites/wsp/files/publications/926200724252_eap_cambodia_filter.pdf August, 2007

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

    • cites [38] Brown J Sobsey MD Loomis D Local drinking water filters reduce diarrheal disease in Cambodia: a randomized, controlled trial of the ceramic water purifier Am J Trop Med Hyg 79 2008 394 400 18784232 source

      Not checked in the free run.

    • cites [39] Harshfield E Lantagne D Turbes A Null C Evaluating the sustained health impact of household chlorination of drinking water in rural Haiti Am J Trop Med Hyg 87 2012 786 795 22987657 PMC3516252 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingown data

    In total, 124 studies were included, with 83 drinking water comparisons (78 separate studies), 20 sanitation comparisons (19 separate studies), and 41 hygiene comparisons (41 separate studies).

    “In total, 124 studies were included in this systematic review, with 83 drinking water comparisons (78 separate studies), 20 sanitation comparisons (19 separate studies), and 41 hygiene comparisons (41 separate studies).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    Scarce evidence was available for the exposure category of drinking water of higher quality supplied on premises, so addition of new evidence substantially changed estimates.

    “Scarce evidence was available for this exposure category; thus, addition of new evidence substantially changed estimates.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Findingnone given

    Around half of the handwashing interventions focused on handwashing promotion with or without soap provision, whereas the other half involved broader hygiene education, such as on food and kitchen hygiene or on safe drinking water and sanitation.

    “Around half of the handwashing interventions focused on handwashing promotion with or without soap provision, whereas the other half of interventions involved broader hygiene education, such as on food and kitchen hygiene or on safe drinking water and sanitation.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Pooled RRs were remarkably close when comparing household or community versus institutional setting, low-income and middle-income versus high-income settings, or different hygiene interventions.

    “Nevertheless, pooled RRs were remarkably close comparing household or community versus institutional setting, low-income, and middle-income versus high-income settings, or different hygiene interventions.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingcitation

    In these interventions, drinking water was not free from microbial contamination and was still stored at household level after intervention implementation.

    “In these interventions, drinking water was not free from microbial contamination24, 95 and was still stored at household level85 after intervention implementation.”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [24] Hunter PR Ramírez Toro GI Minnigh HA Impact on diarrhoeal illness of a community educational intervention to improve drinking water quality in rural communities in Puerto Rico BMC Public Health 10 2010 219 20426831 PMC2876105 source

      Not checked in the free run.

    • cites [95] Pickering AJ Crider Y Sultana S Effect of in-line drinking water chlorination at the point of collection on child diarrhoea in urban Bangladesh: a double-blind, cluster-randomised controlled trial Lancet Glob Health 7 2019 e1247 e1256 31402005 source

      Not checked in the free run.

    • cites [85] Ercumen A Arnold BF Kumpel E Upgrading a piped water supply from intermittent to continuous delivery and association with waterborne illness: a matched cohort study in urban India PLoS Med 12 2015 e1001892 PMC4624240 26505897 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    No sanitation studies reported results by sex.

    “No sanitation studies reported results by sex.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingcitation

    Only one handwashing intervention reported results by sex.

    “Only one handwashing intervention reported results by sex.78”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [78] Roberts L Jorm L Patel M Smith W Douglas RM McGilchrist C Effect of infection control measures on the frequency of diarrheal episodes in child care: a randomized, controlled trial Pediatrics 105 2000 743 746 10742314 source

      Not checked in the free run.

  • May combine two claims.

    Findingown data

    Only two studies were identified for the transition from improved water source on premises to improved source, on premises, and higher water quality, and one study for the transition to improved source, on premises, and continuous supply.

    “We identified only two studies for the transition from improved water source on premises to improved source, on premises, and higher water quality,24, 95 and one study for the transition from improved water source on premises to improved source, on premises, and continuous supply.85”
    Quote in the paperSubstantial claim0 of 3 sources checked
    • cites [24] Hunter PR Ramírez Toro GI Minnigh HA Impact on diarrhoeal illness of a community educational intervention to improve drinking water quality in rural communities in Puerto Rico BMC Public Health 10 2010 219 20426831 PMC2876105 source

      Not checked in the free run.

    • cites [95] Pickering AJ Crider Y Sultana S Effect of in-line drinking water chlorination at the point of collection on child diarrhoea in urban Bangladesh: a double-blind, cluster-randomised controlled trial Lancet Glob Health 7 2019 e1247 e1256 31402005 source

      Not checked in the free run.

    • cites [85] Ercumen A Arnold BF Kumpel E Upgrading a piped water supply from intermittent to continuous delivery and association with waterborne illness: a matched cohort study in urban India PLoS Med 12 2015 e1001892 PMC4624240 26505897 source

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    Safe and reliable drinking water, sanitation that separates excreta from human contact, and handwashing with soap at key times have positive effects on health and social and economic wellbeing.

    “Safe and reliable drinking water, sanitation that separates excreta from human contact, and handwashing with soap at key times, such as after potential faecal contact and before eating or preparing food, have positive effects on health and social and economic wellbeing.1, 2, 3, 4, 5”
    Quote in the paperSubstantial claim0 of 5 sources checked
    • cites [1] Clasen TF Alexander KT Sinclair D Interventions to improve water quality for preventing diarrhoea Cochrane Database Syst Rev 10 2015 CD004794 PMC4625648 26488938

      Not checked in the free run.

    • cites [2] Ejemot-Nwadiaro RI Ehiri JE Arikpo D Meremikwu MM Critchley JA Hand-washing promotion for preventing diarrhoea Cochrane Database Syst Rev 12 2021 CD004265 PMC8094449 33539552

      Not checked in the free run.

    • cites [3] Freeman MC Garn JV Sclar GD The impact of sanitation on infectious disease and nutritional status: a systematic review and meta-analysis Int J Hyg Environ Health 220 2017 928 949 28602619 source

      Not checked in the free run.

    • cites [4] Sclar GD Penakalapati G Caruso BA Exploring the relationship between sanitation and mental and social well-being: a systematic review and qualitative synthesis Soc Sci Med 217 2018 121 134 30316053 source

      Not checked in the free run.

    • cites [5] Wolf J Hunter PR Freeman MC Impact of drinking water, sanitation and handwashing with soap on childhood diarrhoeal disease: updated meta-analysis and meta-regression Trop Med Int Health 23 2018 508 525 29537671 source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Premisereasoning

    For the work of the Lancet Commission on WASH and health, updated estimates of disease burden attributable to WASH are needed, which require up-to-date estimates for the effect of different WASH exposures on risk of diarrhoea.

    “For the work of the Commission, updated estimates of disease burden attributable to WASH are needed, which require up-to-date estimates for the effect of different WASH exposures on risk of diarrhoea.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    The funders of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.

    “The funders of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Three large, high-quality WASH trials have led to discussion and questions about the health effects of basic WASH interventions.

    “These results include those from three large, high-quality WASH trials, which led to discussion and questions about the health effects of basic WASH interventions (eg, provision of improved latrines or POU treatment of drinking water).16”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16] Cumming O Arnold BF Ban R The implications of three major new trials for the effect of water, sanitation and hygiene on childhood diarrhea and stunting: a consensus statement BMC Med 17 2019 173 31462230 PMC6712663 source

      Not checked in the free run.

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductcitation

    Risk of bias in individual studies was assessed using a modified Newcastle-Ottawa Scale considering seven areas of bias, with each study assigned a score of up to nine.

    “Risk of bias in individual studies was assessed by use of a modified Newcastle-Ottawa Scale,28 considering seven areas of bias: selection bias, response bias, follow-up bias, misclassification bias, assessment of bias in outcome, measurement of bias in outcome, and bias in analysis. Each study was assigned a score of up to nine, with a higher score indicating a smaller risk of bias (appendix 1 pp”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [28] Wells G Shea B O'Connell D The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    A systematic review focusing on the effects of sewerage on incidence of diarrhoea included intervention and non-intervention studies, and searched the literature from Jan 1, 1966, to Feb 28, 2010.

    “A systematic review focusing on the effects of sewerage on incidence of diarrhoea included intervention and non-intervention studies, and searched the literature from Jan 1, 1966, to Feb 28, 2010.14”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] Norman G Pedley S Takkouche B Effects of sewerage on diarrhoea and enteric infections: a systematic review and meta-analysis Lancet Infect Dis 10 2010 536 544 20620115 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The UN's Sustainable Development Goals include dedicated WASH targets (SDGs 6.1 and 6.2) that explicitly emphasise equity, address hygiene, and call for higher levels of drinking water and sanitation services for all, and are linked to all other SDGs.

    “The UN's Sustainable Development Goals (SDGs) include dedicated WASH targets (SDGs 6.1 and 6.2), which explicitly emphasise equity, address hygiene, and call for higher levels of drinking water and sanitation services for all,7 and are linked to all other SDGs.8”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [7] UN Transforming our world: the 2030 Agenda for Sustainable Development 2015 United Nations New York, NY

      Not checked in the free run.

    • cites [8] UN Water Water and sanitation interlinkages across the 2030 Agenda for Sustainable Development 2016 United Nations Water Geneva

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductcitation

    The body of evidence was assessed by intervention type using a modified GRADE approach, with five criteria used to potentially downgrade the initial rating.

    “We assessed the body of evidence by intervention type using a modified Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach.29 We then used the five GRADE criteria to potentially downgrade the initial rating: risk of bias in individual studies, inconsistency (I2 >90%), indirectness, imprecision, and publication bias (appendix 2 pp 22–23).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [29] Schünemann HJ Brozek J Guyatt G Oxman AD GRADE handbook: introduction to GRADE handbook https://gdt.gradepro.org/app/handbook/handbook.html#h.w6r7mtvq3mjz 2013

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    In 2020, 2.0 billion people did not have access to safely managed drinking water services, 3.6 billion did not have access to safely managed sanitation services, and 2.3 billion did not have access to handwashing facilities with soap and water at home.

    “According to the WHO–UNICEF Joint Monitoring Programme for Water Supply, Sanitation and Hygiene, in 2020, 2·0 billion people did not have access to safely managed drinking water services, 3·6 billion did not have access to safely managed sanitation services, and 2·3 billion did not have access to handwashing facilities with soap and water at home.9”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [9] WHO UNICEF Progress on household drinking water, sanitation and hygiene 2000–2020: five years into the SDGs 2021 World Health Organization and the United Nations Children's Fund Geneva

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    Two reviewers screened study titles, abstracts, and full texts; these reviewers were not involved in any included studies; conflicts were resolved through consensus with a third reviewer.

    “Two reviewers (JW and SH) screened study titles, abstracts, and full texts. These two reviewers were not involved in any of the included studies as a result of this new search. Any conflicts between the reviewers were resolved through consensus with a third reviewer (SB).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

    Premisecitation

    Frequently updated exposure-response relationships from systematic reviews are needed for annual reporting of progress towards SDG 3 and specifically target 3.9.2 on WASH-related mortality.

    “Frequently updated exposure–response relationships from systematic reviews are also needed for annual reporting of progress towards SDG 3 to ensure health and wellbeing for all, and specifically for target 3.9.2 on WASH-related mortality.17”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [17] WHO SDG 3.9.2 WASH deaths. The Global Health Observatory https://www.who.int/data/gho/data/indicators/indicator-details/GHO/sdg-3-9-2-wash-deaths 2022

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductcitation

    This systematic review and meta-analysis followed PRISMA guidelines.

    “This systematic review and meta-analysis followed Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines.33”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [33] Page MJ McKenzie JE Bossuyt PM The PRISMA 2020 statement: an updated guideline for reporting systematic reviews BMJ 372 2021 n71 33782057 PMC8005924

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    The same two reviewers independently extracted data and assessed risk of bias, and conflicts were resolved by discussion.

    “The same two reviewers independently extracted data and assessed risk of bias. Any conflicts between reviewers over data extraction and bias assessment were resolved by discussion.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Previous systematic reviews on WASH interventions and diarrhoea provided effect estimates for basic sanitation interventions or point-of-use water treatment.

    “Previous systematic reviews on WASH interventions and diarrhoea provided effect estimates for basic sanitation interventions3 or point-of-use (POU) water treatment.1”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [3] Freeman MC Garn JV Sclar GD The impact of sanitation on infectious disease and nutritional status: a systematic review and meta-analysis Int J Hyg Environ Health 220 2017 928 949 28602619 source

      Not checked in the free run.

    • cites [1] Clasen TF Alexander KT Sinclair D Interventions to improve water quality for preventing diarrhoea Cochrane Database Syst Rev 10 2015 CD004794 PMC4625648 26488938

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    A systematic review on different types of WASH interventions searched the literature up to early 2016 and found only one study reporting provision of higher-quality piped water and two studies of continuous water supply.

    “A systematic review on different types of WASH interventions searched the literature up to early 2016 and found only one study reporting provision of higher-quality piped water and two studies of continuous water supply.5”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [5] Wolf J Hunter PR Freeman MC Impact of drinking water, sanitation and handwashing with soap on childhood diarrhoeal disease: updated meta-analysis and meta-regression Trop Med Int Health 23 2018 508 525 29537671 source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductreasoning

    Basic sanitation services without sewer connection were graded as moderate certainty evidence and basic sanitation services with sewer connection were graded as very low certainty evidence mainly due to non-randomised study designs and high risk of bias in services with sewer connection.

    “Basic sanitation services without sewer connection were graded as moderate certainty evidence and basic sanitation services with sewer connection were graded as very low certainty evidence mainly due to the non-randomised study designs and high risk of bias in services with sewer connection (appendix 2 pp 22–24).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Estimates of WASH-related disease burden are not disaggregated by sex, despite calls and guidelines to do so in public health and in the WASH sector.

    “These estimates are not disaggregated by sex, despite calls and guidelines to do so in public health11, 12 and in the WASH sector.13”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [11] Hawkes S Haseen F Aounallah-Skhiri H Measurement and meaning: reporting sex in health research Lancet 393 2019 497 499 30739669 source

      Not checked in the free run.

    • cites [12] Heidari S Babor TF De Castro P Tort S Curno M Sex and Gender Equity in Research: rationale for the SAGER guidelines and recommended use Res Integr Peer Rev 1 2016 2 29451543 PMC5793986 source

      Not checked in the free run.

    • cites [13] Caruso BA Sinharoy SS Gender data gaps represent missed opportunities in WASH Lancet Glob Health 7 2019 e1617 31708141 source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    POU interventions were graded as moderate certainty evidence and all other water interventions as very low certainty evidence.

    “POU interventions were graded as moderate certainty evidence and all other water interventions as very low certainty evidence (appendix 2 pp 22–24).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductnone given

    This study is registered with PROSPERO, CRD42016043164.

    “This study is registered with PROSPERO, CRD42016043164.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given

    Two reviewers independently extracted study-level data and assessed risk of bias using a modified Newcastle-Ottawa Scale and certainty of evidence using a modified GRADE approach.

    “Two reviewers independently extracted study-level data and assessed risk of bias using a modified Newcastle-Ottawa Scale and certainty of evidence using a modified Grading of Recommendations, Assessment, Development, and Evaluation approach.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    Drinking water interventions, specifically drinking water of higher quality and water filtered at POU, reduced risk of diarrhoea up to around 50%.

    “Drinking water interventions, specifically drinking water of higher quality and water filtered at POU, reduced risk of diarrhoea up to around 50%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Public health interventions, such as WASH, are often complex, contain several interacting components, require multiple behaviours and target groups, and are often inherently difficult to randomise or mask, which makes them more likely to be rated as low or very low certainty evidence compared with interventions that can be better controlled, such as clinical interventions.

    “Public health interventions, such as WASH, are often complex and contain several interacting components, require multiple behaviours and target groups, and are often inherently difficult to randomise or mask, which makes them more likely to be rated as low or very low certainty evidence compared with interventions that can be better controlled, such as clinical interventions.104, 105”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [104] Movsisyan A Melendez-Torres GJ Montgomery P Outcomes in systematic reviews of complex interventions never reached “high” GRADE ratings when compared with those of simple interventions J Clin Epidemiol 78 2016 22 33 27038850 source

      Not checked in the free run.

    • cites [105] Murad MH Almasri J Alsawas M Farah W Grading the quality of evidence in complex interventions: a guide for evidence-based practitioners Evid Based Med 22 2017 20 22 27932400 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    We did not systematically search the grey literature, so we could have missed studies not published in peer-reviewed journals.

    “We did not systematically search the grey literature, so we could have missed studies that were not published in peer-reviewed journals.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Providing water on premises is important for overall wellbeing through benefits to quality of life, positive health effects, reduced labour and calorie expenditure, and a potential increase in water quantity for other activities.

    “Other research suggests that providing water on premises is important for overall wellbeing90 through benefits to quality of life, such as the ability to reallocate time previously used for water collection to income generation or leisure,91 positive health effects (eg, on musculoskeletal disorders),92 reduced labour and calorie expenditure,93 and a potential increase in water quantity for other”
    Quote in the paperNot a substantial claim0 of 4 sources checked
    • cites [90] Bisung E Elliott SJ Improvement in access to safe water, household water insecurity, and time savings: a cross-sectional retrospective study in Kenya Soc Sci Med 200 2018 1 8 29355826 source

      Not checked in the free run.

    • cites [91] Whittington D Cook J Valuing changes in time use in low- and middle-income countries J Benefit Cost Anal 10 suppl 1 2019 51 72 32983833 PMC7473062 source

      Not checked in the free run.

    • cites [92] Geere J-A Bartram J Bates L Carrying water may be a major contributor to disability from musculoskeletal disorders in low income countries: a cross-sectional survey in South Africa, Ghana and Vietnam J Glob Health 8 2018 010406 PMC5825974 29497503 source

      Not checked in the free run.

    • cites [93] Chew JF Corlin L Ona F Water source preferences and water quality perceptions among women in the eastern region, Ghana: a grounded theory study Int J Environ Res Public Health 16 2019 e3835 PMC6843409 31614511 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    A previous Cochrane review on drinking water interventions found similar RRs for water treatment at POU but did not provide pooled estimates for source-based water improvements, piped water to households, or higher water quality supplied on premises.

    “A previous Cochrane review on drinking water interventions, which was last updated in 2014 and had narrower inclusion criteria than in this review, found similar RRs for water treatment at POU but did not provide pooled estimates for source-based water improvements, piped water to households, or higher water quality supplied on premises.1”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] Clasen TF Alexander KT Sinclair D Interventions to improve water quality for preventing diarrhoea Cochrane Database Syst Rev 10 2015 CD004794 PMC4625648 26488938

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The GRADE approach was developed for rating the evidence of health-care interventions.

    “Of note, the GRADE approach was developed for rating the evidence of health-care interventions.29”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [29] Schünemann HJ Brozek J Guyatt G Oxman AD GRADE handbook: introduction to GRADE handbook https://gdt.gradepro.org/app/handbook/handbook.html#h.w6r7mtvq3mjz 2013

      Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  • May combine two claims.

    Study design and conductnone given

    There was potential for exposure misclassification, low compliance and response bias, and high heterogeneity across studies, as well as limitations related to the analysis at study level.

    “Additionally, there was a potential for exposure misclassification, low compliance and response bias, and high heterogeneity across studies, as well as limitations related to the analysis at study level.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    Much of sewered sanitation worldwide is not connected to adequate treatment of waste water, resulting in high environmental contamination with faeces and increased risks of diarrhoeal disease in adjacent communities.

    “Furthermore, much of sewered sanitation worldwide is not connected to adequate treatment of waste water, which results in high environmental contamination with faeces and subsequently increased risks of diarrhoeal disease in adjacent communities.102, 103”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [102] Baum R Luh J Bartram J Sanitation: a global estimate of sewerage connections without treatment and the resulting impact on MDG progress Environ Sci Technol 47 2013 1994 2000 23323809 source

      Not checked in the free run.

    • cites [103] Berendes DM Sumner TA Brown JM Safely managed sanitation for all means fecal sludge management for at least 1.8 billion people in low and middle income countries Environ Sci Technol 51 2017 3074 3083 28128924 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Intermittent piped water is a considerable issue in LMICs that affects both water quality and quantity, with hundreds of millions of people estimated to be affected.

    “Second, intermittent piped water is a considerable issue in LMICs that affects both water quality and quantity, with hundreds of millions of people estimated to be affected.80”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [80] Kumpel E Nelson KL Intermittent water supply: prevalence, practice, and microbial water quality Environ Sci Technol 50 2016 542 553 26670120 source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    GBD 2019 estimated substantially larger reductions in risk of diarrhoea with piped water compared with unimproved water (0·64 [0·56-0·73]), high-quality piped water compared with unimproved water (0·20 [0·09-0·49]), and compared with unimproved untreated water (0·09 [0·04-0·23]), and sewered sanitation or septic tanks compared with unimproved sanitation (0·31 [0·28-0·34]).

    “GBD 2019 estimated substantially larger reductions in risk of diarrhoea with piped water compared with unimproved water (0·64 [0·56–0·73]), high-quality piped water compared with unimproved water (0·20 [0·09–0·49]), and compared with unimproved untreated water (0·09 [0·04–0·23]), and sewered sanitation or septic tanks compared with unimproved sanitation (0·31 [0·28–0·34]; appendix 2 pp 24–27).106”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [106] GBD 2019 Risk Factors Collaborators Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019 Lancet 396 2020 1223 1249 33069327 PMC7566194

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Freeman and colleagues found an overall RR of 0·77 (95% CI 0·66-0·91) for the effect of sanitation interventions on risk of diarrhoea in children, which is close to our pooled estimate of all sanitation interventions.

    “Freeman and colleagues3 found an overall RR of 0·77 (95% CI 0·66–0·91) for the effect of sanitation interventions on risk of diarrhoea in children, which is close to our pooled estimate of all sanitation interventions.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Freeman MC Garn JV Sclar GD The impact of sanitation on infectious disease and nutritional status: a systematic review and meta-analysis Int J Hyg Environ Health 220 2017 928 949 28602619 source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    This meta-analysis presents effect estimates by intervention type and by the respective comparison WASH exposure level, instead of combining results of heterogeneous water, sanitation, and hygiene interventions and different comparison exposure levels.

    “This meta-analysis presents effect estimates by intervention type and by the respective comparison WASH exposure level, instead of combining results of heterogeneous water, sanitation, and hygiene interventions, and different comparison exposure levels.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    A Cochrane review on handwashing promotion found similar point estimates for reduction in risk of diarrhoea in communities across LMICs (0·71 [0·62-0·81]) and in day-care facilities and schools in high-income countries (0·70 [0·58-0·85]).

    “A Cochrane review on handwashing promotion and risk of diarrhoea found similar point estimates for the effects of handwashing promotion on reduction in risk of diarrhoea in communities across LMICs (0·71 [0·62–0·81]) and in day-care facilities and schools in high-income countries (0·70 [0·58–0·85]).2”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Ejemot-Nwadiaro RI Ehiri JE Arikpo D Meremikwu MM Critchley JA Hand-washing promotion for preventing diarrhoea Cochrane Database Syst Rev 12 2021 CD004265 PMC8094449 33539552

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    A systematic review found an overall RR of 0·70 (0·61-0·79) for all sewer studies and of 0·41 (0·27-0·61) when sanitation service level at baseline or in the comparison group was very poor.

    “A systematic review looking specifically at the association between sewer connection and risk of diarrhoea found an overall RR of 0·70 (0·61–0·79) for all sewer studies and of 0·41 (0·27–0·61) when sanitation service level at baseline or in the comparison group was very poor.14”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [14] Norman G Pedley S Takkouche B Effects of sewerage on diarrhoea and enteric infections: a systematic review and meta-analysis Lancet Infect Dis 10 2010 536 544 20620115 source

      Not checked in the free run.

49 of 49

  • The authors state this as an assumption.

    Handwashing interventions performed in day-care centres or day-care homes for children, and primary schools from high-income countries represent an increased potential for transmission of faecal pathogens.

    “because we assumed that these settings represented an increased potential for transmission of faecal pathogens.”

  • The paper relies on this without support.

    Previous analyses have often not considered intervention types extending beyond basic WASH services, such as drinking water delivered on premises, of high quality, or continuously available, or sanitation that safely disposes excreta or removes and safely treats it offsite.

    “However, these analyses have often not considered intervention types extending beyond basic WASH services, such as drinking water delivered on premises, of high quality, or that is continuously available, or sanitation that safely disposes excreta or removes and safely treats it offsite.”

  • The paper relies on this without support.

    In LMICs, the sanitary protection and effective treatment provided by both onsite and sewered sanitation systems are often of poor quality.

    “In LMICs, the sanitary protection and effective treatment provided by both onsite and sewered sanitation systems are often of poor quality.”

  • The authors state this as an assumption.

    Additional evidence on the provision of basic WASH services, such as POU water treatment, provision of basic sanitation services, and hygiene promotion, is unlikely to change the results of this analysis to a major extent.

    “We believe that additional evidence on the provision of basic WASH services, such as POU water treatment, provision of basic sanitation services, and hygiene promotion, is unlikely to change the results of this analysis to a major extent. This assumption is supported by the comparison with results from previous reviews.”
4 of 4

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Two explanations are promised, but three are listed

    Minor

    The discussion says there are two possible explanations, then labels the storage-related explanation "Third."

1 of 1

Cites

Flagged first, then by citations

10 of the 107 references couldn’t be matched to a known paper.

Research works printed but not linked: 2

  1. 2020, Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019, Lancet, 396, 1223, 10.1016/s0140-6736(20)30752-2 · DOI · Paper page
  2. Roberts, 2000, Effect of infection control measures on the frequency of diarrheal episodes in child care: a randomized, controlled trial, Pediatrics, 105, 743, 10.1542/peds.105.4.743 · DOI · Paper page

Cited by

Sorted by citations

Related

Authors
Wolf, J., Hubbard, S., Brauer, M., Ambelu, A., Arnold, B. F., Bain, R., Bauza, V., Brown, J., Caruso, B. A., Clasen, T., Colford, J. M., Freeman, M. C., Gordon, B., Johnston, R. B., Mertens, A., Prüss-Ustün, A., Ross, I., Stanaway, J., Zhao, J. T., Cumming, O., & Boisson, S.
Affiliations
  • World Health Organization (CH)
  • Emory University (US)
  • University of British Columbia (CA)
  • Jimma University (ET)
  • University of California, Berkeley (US)
  • United Nations Children's Fund (US)
  • University of North Carolina at Chapel Hill (US)
  • London School of Hygiene & Tropical Medicine (GB)
  • University of Washington (US)
Corresponding author
Wolf, Jennyfer
ORCID
Venue
The Lancet
Publisher
Elsevier BV
Published
2022-07
Volume
400
Issue
10345
Pages
48-59
ISSN
  • 0099-5355 (ISSN-L)
  • 0140-6736
DOI
10.1016/s0140-6736(22)00937-0
PMC
PMC9251635
OpenAlex
W4283761346
Semantic Scholar
ac0a013daa3e1a835fed62d0b9fd9ad754fa97fc
Cited by
377
References
107
Citations by year
2026: 103 · 2025: 110 · 2024: 89 · 2023: 66 · 2022: 8 · 2021: 1
FWCI
9.21
Type
journal article
Language
en
Update notices
Open access
Licence
Locations
  • The Lancet (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • LSHTM Research Online (London School of Hygiene and Tropical Medicine) (acceptedVersion)
  • eScholarship (California Digital Library) (submittedVersion, cc-by)
Funders
  • World Health Organization
  • Emory University
  • University of Bristol
  • Foreign, Commonwealth and Development Office
  • National Institutes of Health
  • National Institute of Environmental Health Sciences (5T32ES12870, T32ES012870)
Topics
  • Health Sciences › Nursing › Nutrition and Dietetics › Child Nutrition and Water Access
  • Health Sciences › Medicine › Infectious Diseases › Viral gastroenteritis research and epidemiology
  • Physical Sciences › Environmental Science › Water Science and Technology › Water Resource Management and Quality
Keywords
childhood diarrhea, drinking water, sanitation, handwashing with soap, water, sanitation and hygiene interventions, household water treatment, solar disinfection, chlorination, household water filtration, handwashing promotion, low- and middle-income countries, SDG 6
MeSH terms
Child, Diarrhea, Hand Disinfection, Humans, Sanitation, Soaps, Drinking Water

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-08.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-08.

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