Groundwater quality evaluation and public health implications of its use in Obudu, southeastern Nigeria

Groundwater within the Obudu area is increasingly affected by geogenic contaminants arising from mineral dissolution processes that influence water chemistry and may impact public health. Arising from this anticipated challenge, careful analysis of the groundwater chemistry was performed to examine its quality and the public health concerns resulting from its domestic use. Twenty groundwater samples were analyzed for cations, anions, and physicochemical parameters to assess their potability and associated health risk. The hydrogeochemical results indicate a dominant Na⁺-K⁺-HCO₃⁻ and minor Ca²⁺-Mg²⁺-HCO₃⁻ water types, suggesting fresh groundwater controlled by feldspar and carbonate dissolution under short residence time conditions. Groundwater risk assessment reveals that 75% of the groundwater pose a high ingestion risk primarily due to chloride enrichment, while adults are more vulnerable to non-carcinogenic effects associated with chronic chloride intake. Children show higher susceptibility to fluoride-related health risks. Although the groundwater quality remains within acceptable limits, treatment is necessary to remove naturally occurring contaminants before consumption. This study provides the first integrated hydrogeochemical and human health risk assessment of groundwater in the Obudu basement complex, highlighting chloride-driven ingestion risks and fluoride exposure in children. It offers a novel, evidence-based framework for predicting groundwater behaviour and inform sustainable water management strategies for similar crystalline basement terrains across sub-Saharan Africa.