Physicochemical Assessment of Drinking Water Qualities in Ogbomoso North and South Local Government Areas of Oyo State Nigeria

Abstract

Water samples collected from twenty-four public groundwater facilities (22 boreholes and 2 wells) and twenty-six public treated water taps located in different quarters of Ogbomoso North and Ogbomoso South Local Government Areas, Oyo State, Nigeria were analysed for their physical and chemical characteristics between May and July 2006. Parameters determined to assess the level of wholesomeness of water from the water facilities included calcium hardness, magnesium hardness, Ca²⁺, Mg²⁺, Cl^- and SO₄^2- ions. Others were electrical conductivity, pH, colour, turbidity, alkalinity, acidity and dissolved solids. Heavy metal contents of the samples were also determined using standard procedures. Ranges of values obtained for groundwater were: Electrical Conductivity 16.88-1725 µS/cm, PH 6.0 – 8.8, total hardness 20.0 – 264 mg/l, Sulphate 2.28 - 3.77 mg/l, chloride 20.0 – 205 mg/l, alkalinity 26.0–524 mg/l, DO ND - 8.5 mg/l. For tap water, the results were pH 5.72-8.4, total hardness 26-130 mg/l, Cl^- 12-51.5 mg/l, residual chlorine 0.15-2.00 mg/l, turbidity 2.10-2.47 NTU. Some of the samples had appreciable amount of Pb²⁺ and Zn²⁺, but Cd²⁺ was not detected in any of the samples. Values obtained generally fell within the WHO’s permissible limits.

Keywords: Groundwater, boreholes, tap water, physicochemical, heavy metals, Nigeria