Integrated Hydrochemical and Epidemiological Assessment of Groundwater Contamination and Disease Burden in Kano Metropolis, Nigeria

Groundwater contamination remains a critical threat to human health and environmental sustainability in rapidly urbanizing African cities. This study provides an integrated hydrochemical, microbiological, geostatistical, and epidemiological assessment of groundwater quality degradation and disease burden in Kano Metropolis, Northern Nigeria. A total of 480 well water samples were collected across eight Local Government Areas (LGAs) and analysed for 18 physicochemical, heavy metal, and microbial parameters using APHA-certified protocols. Results showed widespread exceedances of WHO and NSDWQ drinking-water limits, with particularly high concentrations of nitrate (up to 145.4 mg/L), turbidity (7.9 NTU), electrical conductivity (1341.6 µS/cm), chromium (5.11 mg/L), lead (0.48 mg/L), and E. coli (206 cfu/100ml) during the wet season. MANOVA confirmed significant spatial and seasonal variations (p < 0.001), while PCA revealed two major components explaining 72.8% of total variance, driven by heavy metal pollution and microbial contamination. Hospital data (2011–2022) recorded 172,592 water-related disease cases, with children (< 18 years) disproportionately affected by gastroenteritis (68.9%), cholera (60.1%), and cyanosis (95%), while adults exhibited higher prevalence of kidney disease (92.5%), neurological disorders (87.4%), and cancer (85%). Strong correlations were observed between NO₃ and gastroenteritis (r = 0.76), EC–TDS (r = 0.94), and Cr–Pb (r = 0.82). Findings highlight the urgent need for decentralized water treatment, improved wastewater management, policy enforcement, and WASH interventions. The study contributes a comprehensive evidence base for water security planning and integrated urban environmental management in Nigeria.