Abstract

In Benin City, Edo State, Nigeria groundwater supplies domestic water in many homes but the city’s urbanization and inadequate sanitation is a significant challenge to the quality of the groundwater and its public health safety. The study was used to determine the suitability of the groundwater from forty (40) privately owned boreholes for drinking and domestic use based on their physicochemical and microbiological quality parameters. Physicochemical parameters (pH, turbidity, total dissolved solids, electrical conductivity, nitrate, chloride, iron, zinc, copper, lead and cadmium) and microbiological indicators (total coliforms and Escherichia coli) were analyzed by standard APHA methods. Groundwater quality and the hydrogeochemical relationships were evaluated using descriptive statistics, Pearson’s correlation analysis and the Weighted Arithmetic Water Quality Index (WQI). Most of the physicochemical parameters were within the World Health Organization (WHO) and Standards Organization of Nigeria (SON) guideline values. Mean values were 7.00 ± 0.28 for pH, 0.48 ± 0.18 NTU for turbidity, 129.2 ± 10.7 mg L⁻¹ for total dissolved solids, 258.5 ± 21.3 µS cm⁻¹ for electrical conductivity, and 5.77 ± 2.35 mg L⁻¹ for nitrate. Lead was present at trace levels, and cadmium was not detected, except in low concentrations, in the trace metals. Total coliforms were detected in some boreholes and Escherichia coli in one sample, indicating localized faecal contamination. Although the groundwater exhibited good physicochemical quality (WQI = 28.93), localized microbial contamination demonstrates that chemical compliance alone does not ensure microbiological safety. Routine microbial surveillance, sanitary protection of boreholes, and integrated groundwater management are therefore essential for safeguarding public health.

Keywords: Groundwater quality, Borehole water, Physicochemical characteristics, Microbial contamination, Public health, Benin City