Geochemical Assessment of Groundwater Quality in Enugu State, South East Nigeria

Groundwater constitutes a primary source of potable water for millions of residents across Enugu State, yet systematic geochemical evaluation of its quality remains limited. This study assesses the geochemical characteristics of groundwater in selected communities of Enugu State, South East Nigeria, with focus on major ions, trace elements, and physicochemical parameters. Water samples were collected from boreholes and hand-dug wells in three local government areas using standard sampling protocols. Analyses were conducted for pH, electrical conductivity, total dissolved solids, nitrate, iron, manganese, and heavy metals including lead and chromium. The water quality index was computed to determine potability, and results were interpreted against World Health Organisation and Nigerian Standard for Drinking Water Quality guidelines. Piper diagrams and Gibbs plots were employed to identify hydrochemical facies and the dominant geochemical processes controlling water chemistry. Preliminary field observations suggest elevated iron and manganese concentrations in communities overlying the Eze-Aku Formation, potentially linked to weathering of ferruginous shales. Agricultural practices and open defecation further compound contamination risk in peri-urban zones. Findings are expected to provide a baseline dataset for environmental management agencies and inform groundwater abstraction decisions in the study area. This research contributes to the growing body of literature on geogenic and anthropogenic influences on groundwater chemistry in Nigerian basement and sedimentary terrain. Keywords: groundwater quality, geochemistry, Enugu State, water quality index, hydrochemical facies.