Assessment of Escherichia coli Contamination in Informal Water Sources in Kibera, Nairobi: Prevalence, Drivers, and Implications for Public Health

Abstract

Access to clean and safe drinking water remains a major challenge in informal settlements such as Kibera in Nairobi, due to inadequate infrastructure, poor sanitation and reliance on unregulated water sources. This study assessed the prevalence of Escherichia coli (E. coli) contamination in water sources across 12 villages in Kibera and identified associated risk factors. A total of 72 water samples were collected and analyzed using the membrane filtration method. Overall, 29.2% of the samples were contaminated with E. coli, with the highest contamination rates observed in Soweto (66.7%) and Soweto West (50%). Water delivered by trucks (75.0%) and boreholes (36.0%) had higher contamination levels than public supply systems (21.0%). Samples exposed to pollution from sewage (33.0%), public toilets (50.0%), and dusty rooftops (100%) also showed elevated contamination. Additionally, untreated water sources had significantly higher E. coli levels (63.6%) compared to chlorinated samples (14.9%) (p < 0.0001). These findings highlight the critical influence of water source type, pollution exposure, and treatment practices on microbial water quality. Comprehensive interventions including infrastructure upgrades, regular water quality monitoring, improved sanitation, and promotion of effective household water treatment are recommended.