This study has evaluated the hydrogeochemistry of some parts of the aquifer underlying and near Abakaliki City, Nigeria, to better understand the local groundwater quality conditions. Twelve representative groundwater samples from water boreholes (wells) in the study area were analyzed for their hydrogeochemical properties: pH, electrical conductivity (EC), turbidity, total dissolved solids (TDS), total hardness, chemical oxygen demand, Ca2+, Mg2+, Na+, K+, , , Cl−, , and . The aquifer is situated in the fractured shales of Abakaliki Formation. The dominant ions in most samples are Ca2+, Mg2+, , and Cl−. Furthermore, strong positive correlations exist between EC-TDS, Na+-TDS, , and . Piper trilinear diagrams were used to classify the hydrogeochemical facies, which included Ca-Mg-Cl and Ca-Mg-Na-Cl-SO4 water types. Ratios of Na-Cl ranged from 0.12 to 0.73, with a mean of 0.55, which is consistent with those of fresh water. The results of this study indicate that the groundwater local to the Abakaliki City poses no threat to human consumption, health, or the environment because the concentrations of physicochemical parameters that can be used to evaluate drinking water quality are within the World Health Organization standard specification.