Assessment of Groundwater Quality and Contamination Sources in Ado-Ekiti, Ekiti State

This study assesses the quality of groundwater accessed through boreholes and hand-dug wells in Ado-Ekiti, the capital of Ekiti State, South West Nigeria, and identifies the primary contamination sources affecting this resource. Groundwater is the dominant drinking water source for much of Ado-Ekiti's population given unreliable piped water supply, and its quality is threatened by pit latrine seepage, fertiliser leaching, solid waste disposal practices, and potential legacy contamination from defunct industrial facilities. Thirty groundwater samples were collected from a stratified spatial distribution of boreholes and hand-dug wells across seven residential wards. Parameters analysed include pH, total dissolved solids, electrical conductivity, nitrate, iron, manganese, fluoride, faecal coliform, and E. coli. Results were compared against World Health Organisation drinking water guideline values and Nigerian Standards for Drinking Water Quality. Results show that nitrate concentrations exceed the WHO guideline of 50 milligrams per litre in eleven samples, predominantly from shallow hand-dug wells in densely settled areas with high pit latrine density. Faecal coliform is detected in seventeen of thirty samples, including eight borehole samples, indicating widespread microbiological contamination. Iron and manganese exceed guideline values in samples from laterite-overburden areas, consistent with natural geogenic enrichment. Fluoride concentrations are within acceptable limits across the study area. Well depth is a significant predictor of contamination severity, with hand-dug wells showing consistently higher contamination than boreholes. Recommendations include transition of high-density communities from pit latrines to septic tank systems and mandatory chlorination of community borehole water before distribution. Keywords: groundwater quality, contamination, Ado-Ekiti, nitrate, microbiological safety.