Custodes Futurifor the advancement of humanity

Environmental factor, barrier 5 of 9

Water and sanitation

Unsafe water and sanitation affect billions of people and kill children.

Evidence

  • Safely managed water. The 2025 WHO/UNICEF Joint Monitoring Programme report found 2.1 billion people lack safely managed drinking water, including 106 million who drink untreated surface water.
  • Sanitation. About 3.4 billion people lack safely managed sanitation, including 354 million who practice open defecation.
  • Time. Water collection falls mostly on women and girls, and many in sub-Saharan Africa and Central and Southern Asia spend over 30 minutes a day on it.
  • Deaths. WHO estimated that unsafe water, sanitation, and hygiene caused at least 1.4 million deaths in 2019, including 395,000 children under 5 (7.6% of all deaths at that age), mostly from diarrhea and respiratory infections.

Why it matters: These child deaths remove potential future contributors, including possible pioneers, before any ability can develop.

Proposed and experimental methods

Methods that are proposed, under trial, approved in some places, or tried and then failed. Each shows a stage label and an evidence rating. A stage label shows how far a method has progressed, not whether it works. The stage labels are explained on the environmental factor page.

  • Chlorination at the water point (Approved but not scaled, B). Chlorine dispensers at wells and springs, or chlorine added in the pipe, so households treat water without effort. A meta-analysis of randomized trials (18 of 52 with child mortality data) estimated 24% to 27% lower odds of death under age 5 (odds ratio 0.76), at an estimated 28 to 72 U.S. dollars per disability-adjusted life year averted (Kremer et al., 2023). It is a working paper, the effect is larger than experts expected from diarrhea reduction alone, and GiveWell's own analysis used a smaller effect.
  • Community-led total sanitation (Large trial, B). Village meetings that shame open defecation and push households to build their own toilets, without subsidies. In a cluster randomized trial of 121 villages in Mali, private latrine access nearly doubled (65% versus 35%) and children were taller (height-for-age z score 0.18 higher), but diarrhea did not fall (Pickering et al., 2015).
  • Not shown to help: Household water, sanitation, and handwashing packages (Large trial, A). Three large cluster randomized trials gave rural households chlorine, improved latrines, and handwashing stations. In Kenya none of the interventions reduced diarrhea or improved growth (Null et al., 2018), in Bangladesh diarrhea fell but growth did not improve (Luby et al., 2018), and in Zimbabwe the package had no effect on stunting, anemia, or diarrhea (Humphrey et al., 2019). The authors suggest more thorough community-wide approaches may be needed.

Sources cited on this page

  1. WHO: Burden of disease from unsafe water, sanitation and hygiene, 2019 update (2023) B Moderate
  2. Kremer, M., Luby, S. P., Maertens, R., Tan, B., & Więcek, W. (2023). Water treatment and child mortality: A meta-analysis and cost-effectiveness analysis (NBER Working Paper No. 30835). National Bureau of Economic Research. link B Moderate
  3. Null, C., Stewart, C. P., Pickering, A. J., Dentz, H. N., Arnold, B. F., Arnold, C. D., et al. (2018). Effects of water quality, sanitation, handwashing, and nutritional interventions on diarrhoea and child growth in rural Kenya: A cluster-randomised controlled trial. Lancet Global Health, 6(3), e316-e329. link A Strong
  4. Pickering, A. J., Djebbari, H., Lopez, C., Coulibaly, M., & Alzua, M. L. (2015). Effect of a community-led sanitation intervention on child diarrhoea and child growth in rural Mali: A cluster-randomised controlled trial. Lancet Global Health, 3(11), e701-e711. link B Moderate
  5. South, E. C., Hohl, B. C., Kondo, M. C., MacDonald, J. M., & Branas, C. C. (2018). Effect of greening vacant land on mental health of community-dwelling adults: A cluster randomized trial. JAMA Network Open, 1(3), e180298. link B Moderate

Every source for this factor is listed on the environmental factor page.