Groundwater contamination in sub-Saharan Africa: Implications for groundwater protection in developing countries

Abstract

Abstract Rural and peri-urban communities in the developing world typically rely on boreholes and wells for drinking water, since freshwater on the land surface is heavily polluted and groundwater is perceived to be safe. Nonetheless, in these areas wastewater is managed onsite, often close to the groundwater abstractions points. Unbeknownst to most members of these local communities, this poses an unprecedented threat to their health, since chemicals and pathogens are leaking from onsite systems to groundwater. Polluted groundwater could also act as an environmental reservoir for bacteria and viruses, including new and emerging infectious diseases. In this study, groundwater from rural and peri-urban South Africa was assessed in terms of drinking water quality. Indicators of faecal pollution were identified across the examined boreholes, with E. coli and nitrates concentrations as high as 195 cfu 100mL-1 and 104 mg L-1, respectively, suggesting that onsite wastewater systems have grossly impacted groundwater quality. Elevated concentrations of fluoride and chloride (as high as 8.6 and 392 mg L-1, respectively) were also identified, suggesting that local geological setting also affects groundwater quality. Overall, groundwater was found in need of treatment before consumption, which is currently not the case. To inform local communities and the water industry about the problem, a simple classification model was developed. This could help assess water quality, identify the nature of pollution, suggest the type of treatment required, and prioritise the need for water and wastewater infrastructure investment in the developing world. It can also inform local communities about the impact of their current wastewater management practices on water resources and the pressing need to upgrade them.