Determination of Total Hardness and Mineral Composition of Borehole Water in Gombe State, North East Nigeria

Water hardness attributable to dissolved calcium and magnesium ions is a common quality parameter of concern in groundwater-dependent communities across northern Nigeria, with implications for both domestic use and human health. This study determines total hardness, calcium, magnesium, sodium, potassium, and fluoride concentrations in borehole water samples from twelve communities in Gombe State, North East Nigeria. Water samples were collected in clean polyethylene bottles, preserved appropriately, and analysed within 48 hours. Total hardness was measured by the EDTA titrimetric method, while individual mineral ions were quantified by atomic absorption spectrophotometry and ion chromatography. Results reveal that total hardness values range from 100 to 680 milligrams per litre as calcium carbonate, with five communities showing values above the WHO guideline of 500 milligrams per litre. Elevated calcium and magnesium concentrations are consistent with geological substrates of Cretaceous sedimentary rocks common in the region. Sodium concentrations were generally within acceptable limits. Fluoride was detected at levels ranging from 0.3 to 2.1 milligrams per litre, with one community exceeding the WHO guideline of 1.5 milligrams per litre. The study maps the spatial distribution of hardness across sampled communities and recommends water softening units for severely hard-water communities, as well as targeted fluoride monitoring for affected areas. Keywords: total hardness, borehole water, Gombe State, mineral composition, groundwater quality