Microbiological and physicochemical evaluation of drinking water sources in rural communities of Offa local government area, Nigeria

Access to microbiologically safe drinking water remains a major public health challenge in many rural communities across sub-Saharan Africa. This study evaluated the physicochemical characteristics and microbial quality of drinking water sources across twenty communities in Offa Local Government Area, Kwara State, Nigeria. Water samples were collected from boreholes, hand-dug wells, and surface streams during the dry season and analyzed for pH, turbidity, total coliforms, and Escherichia coli using a chromogenic microbial detection kit. The pH values ranged from 6.2 to 7.9, indicating that most water sources fell within the recommended World Health Organization (WHO) guideline range for drinking water (6.5–8.5). However, turbidity levels varied substantially among source types, with boreholes exhibiting low turbidity (0.8–1.1 NTU) while stream sources recorded significantly higher values (11.9–12.9 NTU), exceeding the WHO recommended limit of 5 NTU. Microbiological analysis revealed widespread contamination across the study area. Total coliform counts ranged from 1 to 200 CFU/100 mL, while E. coli concentrations varied between 0 and 110 CFU/100 mL. Sixteen out of the twenty sampled communities failed to meet WHO microbial safety standards due to the presence of E. coli. Surface water sources demonstrated the highest contamination levels, whereas boreholes exhibited comparatively lower microbial loads and higher compliance rates. A positive relationship was observed between turbidity and bacterial contamination, indicating that elevated particulate matter may facilitate microbial persistence in water systems. These findings highlight the substantial health risks associated with untreated water sources in the study area and underscore the need for routine water quality monitoring, improved sanitation infrastructure, and sustainable water treatment interventions to safeguard community health.