An assessment of the impact of industrial effluent on the heavy metal concentrations and microbiological quality of borehole water in Challawa Industrial Layout, Kano Metropolis, Nigeria

Groundwater remains the primary source of drinking water in Kano metropolis, Nigeria, but increasing industrialization poses serious risks to its quality. The study aims to assess the impact of industrial influent on the concentrations of heavy metals and the microbiological quality of borehole water in Challawa Industrial Layout, in Kano. Borehole water samples were purposively collected from effluent (EL) and non-effluent (NEL) locations during the wet and dry seasons of 2023. Standard methods, as used by the American Public Health Association (APHA) were adopted for sample collection and analysis of heavy metals (Cd, Cr, Pb, As, Zn, Cu, Fe, Mn, Hg) using Atomic Absorption Spectrophotometry, while the microbiological parameters of Total Coliform Count (TCC) and Escherichia coli were determined by membrane filtration. Results revealed significant spatial and seasonal variations in water quality. For EL, heavy metals Cd (0.002–0.15 mg/L), Cr (0.15–6.86 mg/L), Pb (0.01–0.45 mg/L), and As (0.01–0.15 mg/L) exceeded WHO and NSDWQ permissible limits, particularly during the dry season due to reduced dilution. Elevated Zn, Cu, and Mn concentrations were also linked to seepages and infiltration of industrial effluents. Microbial analysis showed TCC and E. coli levels far above acceptable standards in both locations, with wet-season values peaking at 164 cfu/100 ml and 140 cfu/100 ml, respectively, largely due to runoff and infiltration from sewage and septic systems. The findings demonstrate that borehole water in the area is severely contaminated by both heavy metals and microbiological loads, rendering it unsafe for direct consumption. Regular monitoring, treatment, and enforcement of effluent discharge regulations are strongly recommended to safeguard public health.