Assessing microbial and nutrient contamination in urban groundwater: health risk implications for waterborne diseases in Harare, Zimbabwe

Harare faces recurring waterborne diseases linked to poor groundwater quality. Yet, there is limited evidence on the extent of contamination, and the magnitude of health risks. The study assessed groundwater quality to identify potential health risks. Water samples were collected from 48 boreholes in eight districts. Quantitative microbial risk assessment was used to estimate health risks. Average turbidity was ≥1 NTU (nephelometric turbidity unit) posing water safety concerns. The maximum nitrate levels of 145 mg/L and 71 mg/L in North West and South districts exceeded the guideline, posing potential health risks to consumers. The maximum ammonia level of 43 mg/L in East district exceeded the acceptability thresholds. Chlorine residual was below 0.2 mg/L for effective disinfection. E. coli was detected in 75% of the districts, and its health risk exceeded the benchmark of 1 × 10−6 disability-adjusted life years (DALYs). There is need for establishing community managed disinfection systems and improving waste management practices to improve groundwater quality and safety.