Survey and Identification of Biological Contaminants in Sources of Drinking Water in Biu Metropolis, Biu Local Government Area, Borno State, Nigeria

Safe drinking water remains a public health priority in developing nations where untreated sources are commonly used. This study assessed the physicochemical and biological quality of drinking water from borehole, sachet, surface, and well water sources in Biu Local Government Area, Borno State. A total of 120 water samples were collected between April and September 2026 and analysed using standard methods. Physicochemical parameters differed significantly among sources (p < 0.05), with sachet water recording the lowest conductivity (278.48 μS/cm) and TDS (195.43 mg/L), while surface water had the highest (731.04 μS/cm and 469.76 mg/L, respectively). Bacterial and fungal contaminants were detected across all sources. Borehole water contained the greatest number of presumptively identified bacterial types (20), while well water contained the fewest (14). Fungal genera including Aspergillus, Penicillium, Fusarium, Candida, Rhizopus, and Cryptococcus were detected, with sachet water containing the highest number of fungal types (13). Identifications were presumptive; confirmatory molecular methods and quantitative microbial enumeration were not performed. The findings indicate that water sources in the study area harbour bacterial and fungal contaminants of potential public health concern. Routine monitoring of physicochemical, bacteriological, and fungal parameters is recommended for all drinking-water sources in the study area.