Water quality assessment of various drinking water sources in some urban centres in Enugu, Nigeria: estimating the human health and ecological risk

The water qualities of the table, municipal and groundwater sources in some parts of Enugu State, Nigeria, were examined to determine their suitability for drinking. A total of 12 physicochemical properties (PCPs) and 9 heavy metal (HM) concentrations, distributions, source analysis, health, and ecological risks were evaluated. The water samples were collected in triplicate from 28 sampling locations from December 2021 to February 2022. The HMs were quantified using Flame Atomic Absorption Spectroscopy and titrimetric analysis. The mean HM values ranged within 0.0286 +/- 0.0324-13.6067 +/- 35.582, 0.0268 +/- 0.0370-2.7450 +/- 1.8666, and 0.0097 +/- 0.0157-0.7718 +/- 0.5080 mg/L in table, municipal and groundwater, respectively. Mean concentrations of Fe, Cd, Pb, and Ni were above recommended WHO/NIS standards in all water samples. For PCPs, the mean turbidity values for table and groundwater and all mean pH values of groundwater were above safe limits. The Hazard Quotient (HQ) and the Hazard Index (HI) for oral exposures in adults and children to HM were < 1. However, all HQ and HI for Cd dermal exposure in children for all drinking water sources were > 1. Source analysis and ecological risk assessments confirmed that HM pollution was of both geogenic and anthropogenic origins. Ecological assessments also revealed that pollution levels ranged from low risk of Ni concentrations in table water to very severe risk for Cd levels in groundwater.