ABSTRACT
This study investigated the impact of close proximity of boreholes from septic tanks on groundwater quality. Water samples were collected for three months (April to June, 2018), from four (4) household boreholes in Egor L.G.A, in Benin City, Edo State, and composite sampling was carried out for the stations. UNIBEN Water board was used as a control station for the study. The water samples were analyzed for both physicochemical and bacteriological properties which include; pH, temperature, conductivity, suspended solid, turbidity, alkalinity, chloride, phosphate, sulphate, nitrate, ammonium, DO, BOD, Total coliform bacteria and Faecal coliform counts. Locations and distances of boreholes from septic tanks were determined using Global Positioning System (GPS) device and a surveyor tape. The results indicated a pH ranging from (4.75-5.43) for all the stations, E/C of (20-43.33μS/cm), temperature (25.27-28.20°C), turbidity (0.0-6.67NTU), S/S (0.0-3.83mg/l), alkalinity (3.33-6.0mg/l), chloride (10.59-16.47 mg/l), phosphate (0.09-0.15 mg/l), sulphate (1.33-3.83 mg/l), nitrate (2.28-2.86 mg/l), ammonium (2.75-3.49 mg/l), DO (5.62-7.30 mg/l), BOD (2.45-2.93 mg/l). Results were compared with WHO and NSDWQ drinking water quality standards. Bacteria count in all stations indicated the presence of Total coliform count (43.33-4408.33cfu/100ml), E. coli (0.0cfu/100ml), Strept. Faecalis (0.0cfu/100ml). It was noted from correlation analysis that bacteria load in the water increased with decreasing distance of borehole from septic tank. It was concluded that there was possible contamination of the borehole water from septic tanks due to the close proximity to the boreholes, as the distance between the boreholes and septic tanks in all stations fell short of the minimum recommended distance of 30m by WHO. From the bacteriological result, the water from all the stations is not potable; hence it raises serious public health concerns to the residents of these areas. The study recommends treatment of borehole water before consumption; regular monitoring of drinking water source and also, Government should fund further studies on groundwater quality control and factors that may lead to water contamination within the study area and beyond.
