Evaluation of composite groundwater quality for consumption in Harare, Zimbabwe

Poor water quality has been linked to health risks in Harare, Zimbabwe. This study was conducted to evaluate the composite groundwater quality for consumption. The objectives of the study were to evaluate the suitability of groundwater for consumption, determine the influence of different water quality parameters on the final water quality index and identify health risks associated with nitrate and E. coli. Water samples were collected (2021 to 2023) from selected boreholes in 8 districts. The Canadian Council of Ministers of the Environment water quality index was used to categorize the composite water quality and determine the parameters which failed to meet the World Health Organization (WHO) guidelines of 2017. The quantitative hazard quotient and microbial risk assessments were used to assess the health risk from nitrate and E. coli exposure in drinking water. The study confirmed that 75% of the districts had poor water quality index category mainly due to average turbidity, E. coli and chlorine residuals which failed to meet the WHO guidelines. The study also found that children were vulnerable to nitrate contamination health risks as the hazard quotient exceeded 1 in 25% of the districts. The estimated disease burden from E. coli exceeded the WHO benchmark of 1 × 10⁻⁶ DALYs in 75% of the districts, showing a significant health risk to waterborne diseases. The study highlights the need for water quality improvements in Harare with specific interventions such as low-cost household treatment as the short-term solution, while improving sanitation and waste management practices could be the long-term solutions to improve water quality for consumption to protect public health.