Effects of adding household water filters to Rwanda's Community-Based Environmental Health Promotion Programme: a cluster-randomized controlled trial in Rwamagana district

Unsafe drinking water remains a major cause of mortality and morbidity. While Rwanda's Community-Based Environmental Health Promotion Programme (CBEHPP) promotes boiling and safe storage, previous research found these efforts to be ineffective in reducing fecal contamination of drinking water. We conducted a cluster randomized controlled trial to determine if adding a household water filter with safe storage to the CBEHPP would improve drinking water quality and reduce child diarrhea. We enrolled 1,199 households with a pregnant person or child under 5 across 60 randomly selected villages in Rwamagana district. CBEHPP implementers distributed and promoted water purifiers to a random half of villages. We conducted two unannounced follow-up visits over 13–16 months after the intervention delivery. The intervention reduced the proportions of households with detectable E. coli in drinking water samples (primary outcome) by 20% (PR 0.80, 95% CI 0.74–0.87, p < 0.001) and with moderate and higher fecal contamination (≥10 CFU/100 mL) by 35% (PR 0.65, 95% CI 0.57–0.74, p < 0.001). The proportion of children under 5 experiencing diarrhea in the last week was reduced by 49% (aPR 0.51, 95% CI 0.35–0.73, p < 0.001). Our findings identify an effective intervention for improving water quality and child health that can be added to the CBEHPP.