Anthropogenic activities in the watershed and the type surrounding rock determine the suitability for domestic and agricultural uses of borehole water in the Far North Region (Cameroon)

Groundwater is the primary source of drinking water in sub-Saharan Africa, yet its quality and contamination sources often receive little attention, despite the region’s vulnerability to waterborne diseases and food insecurity. This study aimed at determining the suitability of groundwater for domestic and agricultural uses and the contributing factors in the Far North Region of Cameroon. Water samples were collected from 47 boreholes across the study area from January to April 2023. The heterotrophic aerobic and mesophilic bacteria (HAMB) and fecal contamination indicators were isolated and counted on agar using plating and membrane filtration techniques. Some physicochemical parameters such as pH, electrical conductivity, temperature, total dissolved solids, salinity, and concentrations of Cl ⁻ , Ca ²⁺ , Mg ²⁺ , NO ₃ ⁻ , SO ₄ ²⁻ , Fe ²⁺ , Na ⁺ , K ⁺ , alkalinity, oxidability, total hardness, and suspended solids (SS) were measured. The sodium adsorption ratio (SAR), potential salinity (PS), Kelly ratio (KR), and magnesium hazard (MH) indices were calculated to assess the suitability of the water for agricultural use. Results showed that 66.67% of the boreholes were contaminated with total coliforms, E. coli , and fecal enterococci, indicating fecal contamination and unsuitability for human consumption. The groundwater in the granitic areas exhibited high mineralization, with electrical conductivity reaching 2620 µS/cm, mainly due to the water-rock interaction; releasing large quantities of calcium, magnesium, fluoride, sodium, and potassium ions. The results suggest that chemical and biological contamination of groundwater occurs through the hydrolytic release of ions contained in the rocky substrate and through anthropogenic activities.