This paper provides a formal systematic review and meta-analysis examining the evidence of the effectiveness of interventions intended to reduce illness through improvements in drinking water, sanitation facilities and hygiene practices. The comprehensive literature search and bibliographic review shows that in developing countries, water quality interventions, specifically point-of-use treatment, reduced diarrhea illness levels, but this effect was mainly seen with the provision of household connections and use of water without household storage. Hygiene interventions, especially those promoting hand-washing, were effective. Only limited data were available for sanitation interventions, but these suggested effectiveness in reducing diarrhea. Multifactorial interventions consisting of water supply, sanitation and hygiene education acted to reduce diarrhea but were not more effective than individual interventions
