Quantitative microbial risk assessment (QMRA) of <i>Escherichia coli</i> in water supplied to selected schools in Limpopo Province, South Africa

ABSTRACT In many developing countries, access to safe, potable water by school children is limited, yet water is an irreplaceable resource that is crucial to children's well-being and learning performance. This seasonal study assessed the microbial contamination vulnerability of groundwater sources in 20 primary schools across two municipalities of Limpopo Province, South Africa. Sixty random samples were collected and analysed for faecal indicator organisms using the membrane filtration method. Further, the quantitative microbial risk assessment (QMRA) model was employed to estimate the annual risk of infection and illness among the children. The results revealed that Escherichia coli levels varied between 0 and 65 CFU/100 mL and between 0 and &amp;gt;100 CFU/100 mL, in the dry and wet seasons, respectively. Across all sites, in both seasons, total coliforms were detected. Hence, 100 and 42.11% of boreholes failed to comply with the WHO and South African National recommended limits for total coliforms and E. coli. In some of the samples (20–30%), unacceptable annual risk exceeding 10−4 was recorded. Estimation of QMRA indices suggests that some of the groundwater from the investigated sites is a hazard.