Assessment of Heavy Metal and Fecal Contamination in Domestic Well Water in Gumel Metropolis, Nigeria: Public Health Implications

Access to safe drinking water remains a critical public health challenge in many semi-arid regions of Nigeria.  This study evaluated the bacteriological, physicochemical, and heavy metal quality of well water in Gumel Metropolis, Jigawa State, to assess its safety and potential health risks.  Twenty-four well water samples were collected from four villages (Garin Gambo, Zuge, Maikarya, and Mele) over three months and analyzed using standard methods.  The results revealed significant contamination.  Physicochemical analysis showed that pH and temperature were within World Health Organisation (WHO) limits, but conductivity (up to 1332.67 µS/cm) and turbidity (up to 11.87 NTU) exceeded WHO guidelines, indicating ionic and sedimentary pollution.  Bacteriologically, all samples were contaminated with total coliforms, with Most Probable Number (MPN) values reaching 723.33 MPN/100mL.  Biochemical characterization confirmed the presence of pathogenic Escherichia coli and Klebsiella pneumoniae, indicating faecal pollution and a high risk of waterborne disease.  Heavy metal analysis revealed alarming concentrations of Cadmium (0.28–0.53 mg/L), Lead (up to 0.04 mg/L), and Chromium (up to 0.33 mg/L), exceeding WHO standards by factors of 93–176, 4, and 6.6, respectively.  The computed Heavy Metal Pollution Index (HPI) was critically high, ranging from 623 to 1156, far surpassing the critical threshold of 100.  Statistical analysis using ANOVA showed no significant spatial variation (p > 0.05) for most parameters, indicating widespread pollution, whereas Pearson's correlation showed a significant negative relationship between zinc and MPN (r = -0.727, p < 0.05).  The study concludes that well water in Gumel Metropolis is severely contaminated with heavy metals and pathogenic bacteria, posing serious health risks.