The state of wastewater management in South Africa: data gaps, missing wastewater, and Green Drop reporting

Untreated or poorly treated wastewater is a major contributor to freshwater pollution. In South Africa, the Green Drop (GD) assessments report the national status of wastewater management. However, GD reporting was halted between 2013 and 2022. We aimed to determine the consequences of the lengthy cessation in GD monitoring, isolate issues not highlighted in GD reporting, and interrogate the current status of wastewater management in South Africa. The GD reports showcase the dire state of South Africa’s wastewater treatment works (WWTW). However, we found that the biggest problem not emphasised in GD reporting is ineffective management of sewage reticulation (i.e., collection and distribution), with evidence that large amounts of wastewater are going missing (i.e., not reaching WWTW for treatment). There was a decrease in the daily volume of wastewater treated (DVT) across South Africa between 2013 and 2021, despite the population increasing by ~5.52 million (10%) during that period. We highlight the severity of this issue through a case study on the city of Pietermaritzburg: we estimated a ~19.66 MLꞏday⁻1 deficit between predicted and measured DVT at the Pietermaritzburg Darvill WWTW in 2022, with the deficit correlating to high Escherichia coli concentrations (indicative of raw sewage pollution) in the rivers within the Pietermaritzburg area. If reticulation failures are not addressed, then even if the dismal performance of WWTW in South Africa is remedied, wastewater pollution impacts will persist. The wastewater crisis is creating water scarcity, increasing the difficulty of using and re-using water resources, and poses a substantial health risk. Addressing the crisis requires adequate data. Though the current GD assessments are essential to identifying problematic WWTW, serious data gaps remain that necessitate improved monitoring, potentially augmented by citizen science. Mitigating the wastewater crisis is critical to safeguarding freshwater ecosystems, securing safe and resilient water supplies, and achieving the Sustainable Development Goals (SDGs).