Post-supply microbial deterioration of household-stored drinking water in Kinshasa, Democratic Republic of the Congo

Abstract

Safe drinking water is essential for public health, yet post-supply deterioration during household storage remains a widespread challenge in developing countries. This study anticipated that domestic storage practices in Kinshasa may compromise water quality, exposing consumers to health risks. We therefore evaluated microbial water deterioration during household storage. Prior to microbiological study, a retrospective questionnaire was administered to 180 households in nine quarters of Lemba municipality in Kinshasa to document household practices. Based on this survey, municipally treated tap water and borehole water were stored in drums grouped in 2-experimental categories: drums sealed over 15 days and drums opened twice daily. Microbial analyses were longitudinally performed, evaluating six microbial indicators: Escherichia coli, total coliforms, fecal coliforms, Pseudomonas aeruginosa (P. aeruginosa), Enterococcus, and yeasts. Survey data revealed 60% of respondents relied on tap water; 62% reported storing water for at least 1–3 days due to scarcity and irregular supply; and 58% kept containers sealed regardless of the storage period, while 40% mentioned opening them daily or several times a day for water collection. Microbial enumeration indicated that borehole water was initially contaminated with 5/6 microbial groups, whereas tap water was contaminated only with 2/6 microorganisms. Microbial loads were consistently higher in frequently opened containers compared to sealed ones, suggesting possible re-contamination. However, yeasts and P. aeruginosa counts significantly increased in sealed containers for both water types, suggesting intrinsic microbial regrowth. These findings highlight the vulnerability of household-stored water to microbial degradation, underscoring the need for interventions to safeguard water quality.