Evaluation of Groundwater Quality for Domestic Use in Federal Capital Territory, Nigeria

Abstract

This research evaluated the quality of groundwater for domestic uses among the three major lithological units (older granite, migmatite-gneiss complex and metasediment) of the Federal Capital Territory (FCT), Nigeria. The research adopted an experimental research design whereby a total of thirty (30) groundwater samples (from boreholes and wells) were collected using stratified sampling at a rate of five samples per lithological unit for two seasons (wet and dry). Results of analysis for the wet and dry seasons, respectively were as follows: pH (3.51-6.58 & 4.2-6.62), temperature (15-22.80C & 17-21.80C), Electrical conductivity (13.4-1669S/cm & 20.5-1442.9S/cm), Turbidity (0.63-32.6 mg/L & 0.6-30.8 mg/L), Dissolved Oxygen (7.87-11.10 mg/L & 6.41-9.41 mg/L), Nitrate (1.0-71.5 mg/L & 0.8-68 mg/L), Total dissolved solids (24.5-622.9 mg/L & 13.8-592 mg/L), Total Alkalinity (71.1-178 mg/L & 71.8-179.2 mg/L), Total hardness (20.2-668.6 mg/L & 15.9-659.1 mg/L), Calcium (14-298 mg/L & 13-282 mg/L), Magnesium (1.5-8.01 mg/L & 1.0-10.0 mg/L), Copper (0.08-0.42 mg/L & 0.04-0.36 mg/L), Iron (0.1-0.32 mg/L & 0.16-0.36 mg/L), Bicarbonate (7.48-306.2 mg/L & 8.8-300.6 mg/L).
Except for pH, which recorded below the World Health Organization and Nigeria Standards for Drinking Water Quality of 6.5-8.5 in all the samples, all parameters in the study areas fall within acceptable limits for both standards, although two samples (HDW1 and HDW2) recorded high nitrate and iron concentrations in both seasons.
Hypothesis test show no significant difference between the groundwater quality for the two seasons (p=0.117718>0.05) and strong positive correlation between the seasons' data sets (r=0.999632). The study concludes that the water quality for the two seasons classified using the CCME Water Quality Index (WQI) are marginal (55.45 for wet season and 55.46 for dry season), the FCT ground water remains constantly under the threat of contamination and needs to be treated before use. Further ongoing monitoring and assessment of groundwater in the region are necessary due to changing quality from constant anthropogenic activities.