Physicochemical and bacteriological assessment of groundwater quality in Etsako east local government area of Edo state, Nigeria

Abstract

One of the environmental determinants of health is the quality of drinking water. Good quality water is devoid of impurities and pathogenic microbes. Water samples from 12 boreholes at two locations in Etsako East Local Government Area (LGA) were analyzed to evaluate their quality. The physicochemical parameters were measured using standard methods and Total Heterotrophic Bacterial Count (THBC) was performed using nutrient agar. The Total Coliform Count (TCC) was performed using the multiple tube technique also called the most probable number (MPN). The physicochemical properties of all the borehole water samples analyzed were within the WHO permissible limits except pH, which was acidic in Agenebode region. The heavy metal concentrations did not conform to the WHO recommended standards, e.g., in Agenebode, Lead was 0.62±0.00 mg/L and Cadmium 0.01±0.00 mg/L and in Okpella it was 0.43±0.00 mg/L and 0.02±0.00 mg/L, respectively. The bacteriological parameters such as total coliform counts and total heterotrophic bacteria counts in Agenebode (277±406.57 MPN/100mL), (34.67 × 10³±23.67 CFU/mL) and Okpella (786.67±583.19 MPN/100mL), (41.50 × 10³±24.09 CFU/mL), respectively, also exceeded the WHO permissible limits. In one of the locations (Agenebode) a total of four bacterial groups were isolated from the water samples, i.e., Staphylococcus spp., Neisseria spp., Streptococcus spp., and E. coli, while in the other location (Okpella) a total of five bacteria were isolated from the water samples, i.e., Staphylococcus spp., Klebsiella spp., Enterococcus spp., Enterobacter spp., Yersinia spp. The heavy metals contamination and high bacteria load of the water samples render them unfit for human consumption.