Researchers at the Emory Rollins School of Public Health, in collaboration with the WHO, UNICEF, and others recently published (July, 2022) a systematic review and meta-analysis on effectiveness of WASH interventions.

This meta-analysis provided up-to-date estimates on the burden of diseases attributed to WASH. The two previous systematic reviews were published in 2014 and 2018. This new systematic-review included 124 studies (83 observations for water, 20 for sanitation and 41 for hygiene).

The main quantitative findings are summarized below:
When compared with unimproved water source, the reduction in risk of diarrhoea were:

  • 52% for improved drinking water on premises with higher water quality
  • 50% for water filtered at Point-of-Use (POU)
  • 21% for basic sanitation without sewer connection
  • 47% for basic sanitation with sewer connection
  • 30% for hygiene interventions.

Sex-disaggregated data is very limited in WASH context, only 4% of the included studies. (In my opinion, this is a huge data gap).

Highlights, impressions and suggestions from this meta-analysis:

  1. Drinking water of higher quality and water filtered at POU are effective (up to around 50%) in reducing diarrheal risk.
  2. Basic sanitation services without sewer connection were associated with a moderate reduction in risk of diarrhoea.
  3. Sewered sanitation has a greater effect on health than on-site sanitation. (there are several explanations for this suggestion)
  4. The risk reduction of diarrhoeal disease from handwashing interventions is impressive.

It is an open access paper.

What do you think about their findings? Surprising?

Journal reference:

Wolf, J., et al. (2022) Effectiveness of interventions to improve... (More)