Water SA

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

P. Mark Graham — 2025-05-21

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 ML·day-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).

Health assessment and restoration options for the degraded Swartkops Estuary, South Africa

J.B. Adams — 2025-05-21

The Global Biodiversity Framework and UN Decade of Ecosystem Restoration have focused attention on the need for health assessments and restoration options for estuaries. This study focused on the Swartkops Estuary because of its biodiversity and socio-economic importance that are threatened by pressures from surrounding development and human activities. The ‘Present Ecological State’ (PES) was assessed using an estuarine health index to determine the health score of the estuary compared to historical reference conditions, using both abiotic and biotic indices. Results showed that nutrient-rich freshwater from upstream wastewater treatment works and stormwater canals has increased freshwater inflow to the estuary by 41% compared to natural, leading to eutrophication and persistent harmful algal blooms. Development and disturbance have transformed the estuary functional zone, impacting on macrophyte and bird abundances. Invertebrate bait organisms and linefish species are overexploited. As a result, the health of the Swartkops Estuary has continued its downward trajectory from 53% of its natural state in 2015 to 47% at present. This study is the first to identify potential remediation measures aimed at improving the current ecological health of the estuary. These include the removal of wastewater inputs and the restoration of salt marsh habitat, which would improve the ecological status from a largely modified to moderately modified condition. This study highlights how difficult it is to restore an estuary once deteriorated, while emphasising the need for an implemented estuary management plan with well-defined management, conservation, and restoration goals.

Reduction of pollution levels in the Chatty River, Gqeberha, South Africa, through sustainable drainage systems: Bethelsdorp sub-catchment case study

Anabel Matalanga — 2025-05-21

Chatty River, located in Gqeberha, South Africa, is the largest tributary feeding into the Swartkops Estuary, and a major source of pollution. Its catchment is mainly occupied by low-income residential areas resulting in polluted stormwater runoff from litter and raw sewage discharge. This study employed both experimental and modelling approaches to assess pollution sources and mitigation options. Water quality sampling was conducted across various sub-catchments draining into the Chatty River, and subsequently Swartkops Estuary, to evaluate the physical, nutrient, and microbiological characteristics, revealing eutrophic and hypertrophic conditions and high gastrointestinal health risks to residents. Additionally, hydrological and hydraulic modelling were performed using PCSWMM (Personal Computer Stormwater Management Model) for the Bethelsdorp River sub-catchment. Various scenarios were developed to test the retrofitting of sustainable drainage system (SuDS) interventions for improving water quality. The model scenarios include: the ‘As-Is’ model representing the current situation; the ‘Pre-Development’ model representing the state before the influence of anthropogenic activities, and various retrofitted SuDS intervention models, including the reduction of pollutant concentration through the rehabilitation of historic wetland areas, a constructed wetland, a retention pond, and various infiltration practices. Rehabilitating the wetlands offered the highest impact in terms of water quality improvement, with a mean pollutant reduction of 30%. However, a combination of all the interventions had the highest pollutant removal when functioning efficiently, of 72% and 80% for dissolved inorganic phosphorus (DIP) and total suspended solids (TSS), respectively. Forming a treatment train was seen as the most effective strategy to adequately improve water quality in the catchment to meet the standards presented by various guidelines.

Characterisation and water resource assessment of Shashani sand river, Matabeleland South, Zimbabwe

Tinashe Shumba — 2025-05-21

Sand rivers are a common water source throughout the dry regions of the world. However, there is limited literature with regards to their storage capacity and potential water supply. The objective of this study was to characterise the Shashani sand river and assess its potential for water supply, by. estimating aquifer volume and recharge. Sand depth was determined by mechanical probing, and surface area of the river by remote sensing, enabling calculation of aquifer volume. Storage capacity was estimated by multiplying the volume by the porosity, and climatic data used to determine potential recharge into the Shashani sand river, for typical dry, wet and normal years. The Soil Conservation Service (SCS) curve number method was used to determine runoff into Shashani River. The volume of the aquifer was estimated at 23 900 000 m³ . The potential recharge from Shashani sand river before abstraction and water losses was 843 831 880 m3 for a wet year, 227 662 070 m³ for a dry year and 550 450 900 m³ for a normal year. The study showed that Shashani sand river has a very high water storage capacity and has the potential to supply water to farmers for domestic use and irrigation of community gardens throughout the year. Findings from this study are useful to water authorities for water budgeting and agricultural planning. Further studies are required to investigate the sustainable abstraction rate. This study will inform the procedures used in the characterisation of sand rivers for agricultural usage; the approach used is lower in cost than others used in the characterisation of resources in the region. The chosen methodology can be applied in the quantification of other sand rivers globally.

The prospects for rainwater harvesting at the University of Cape Town

Tšepiso Lepota — 2025-05-21

The viability of rainwater harvesting (RWH) as a fit-for-purpose water source for supply at the University of Cape Town (UCT) was investigated to reduce dependence on municipal water treated to unnecessarily high standards for purposes like toilet-flushing. Representative buildings on the UCT Upper and Middle Campuses, a parking area, and the tennis court on Upper Campus were identified as potential catchment areas. The ‘Yield after spillage’ (YAS) algorithm was used to identify the relationship between water demand and supply for various flush frequencies and storage sizes. The cost savings from harvested rainwater were estimated using the City of Cape Town (CoCT) 2021/2022 tariffs for Level 1 and Emergency Response water restrictions. A 20-year discount period and a 4% interest rate were used to determine the capital recovery amounts of the cost of ownership of the RWH systems. A multi-criteria analysis (MCA) tool that considered 3 weighting scenarios of the harvestable rainfall and economic viability was used to identify the most viable RWH systems. It was found that student residences could potentially reap the greatest benefits from installing RWH systems. Approximately 4 900 kL·yr−1 and 4 000 kL·yr−1 of rainwater can be harvested from Woolsack and Fuller Hall, respectively, if 100 kL tanks are provided, depending on the toilet flush frequency. The tennis court was identified as the most viable catchment for RWH. Approximately 7 500 kL·yr−1 of rainwater could be harvested if 1 000 kL tanks are provided when the rainwater from the tennis court catchment is supplied to all Upper Campus buildings. It was also concluded that UCT is in a relatively good location for RWH due to its rainfall pattern as compared with those enjoyed by other universities across South Africa.

Mitigation of opportunistic pathogens in hot water systems: a review focused on premise plumbing in South Africa

S.J. Moodley — 2025-05-21

Water reticulation systems (i.e., premise plumbing) serve as a reservoir for opportunistic premise plumbing pathogens (OPPPs) to survive within these premise systems. OPPPs can be transmitted to individuals mainly via inhalation of aerosols from these water systems. These OPPPs can adapt, thrive and survive under a range of different conditions, which include high temperatures and low oxygen levels during stagnation, conditions often associated with household plumbing systems, including hot water systems (HWS). Hospitals are of specific concern as infections caused by OPPPs predominantly affect individuals who have underlying illnesses or health conditions. The current South African National Standard (SANS) 241 for drinking water does not provide information regarding testing for the presence of OPPPs, while the SANS 893 and 893-1 standards only provide a guideline for Legionella in water systems. The presence of OPPPs within HWS and premise plumbing is a concern, and a need exists to establish remediation and mitigation measures to control the presence of OPPPs in buildings. This review addresses risk analysis, evaluation and measures, which include the control of geyser temperatures and training of plumbers, as well as sampling and detection of OPPPs. This should limit the number of infections amongst individuals and will thus lessen the financial burden on health care systems and the economy.

Investigating antimony leaching from polyethylene terephthalate (PET) bottles: characterization with SEM–EDX and ICP–OES

Yassin T.H. Mehdar — 2025-05-21

Polyethylene terephthalate (PET) is currently the most widely used type of plastic. PET plastic benefits include that it is lightweight, safe, cheap, and recyclable. Drinking water is an important route for human exposure to contaminants. One method of exposure is through leaching of antimony (Sb) from polyethylene terephthalate PET plastic. Antimony is a toxic element which causes harmful symptoms such as respiratory irritation, dysphagia, vomiting and eye and mucous membrane irritation. Leaching of antimony from three commercially available PET plastics was investigated in this study. The potential leaching of Sb was observed under different pH values, temperatures, and storage times. In this study, elemental mapping using scanning electron microscopy–energy dispersive x-ray spectroscopy (SEM–EDX) and inductively coupled plasma– optical emission spectrometry (ICP–OES) were employed to determine the weight percentages of antimony (Sb) on the inner surfaces of the PET plastic. The results revealed the presence of Sb in PET material, with significantly higher concentrations in PET 3, measured at 0.844 μg/L. Temperature and pH were investigated as factors influencing Sb leaching over time. The concentrations of Sb in bottled water ranged from 0.02 to 2.14 μg/L at different temperatures (25, 40, 50, or 60°C) and from 0.02 to 1.9 μg/L at pH values (6.5, 7, or 7.5) over 200 days. The maximum Sb concentrations reaching 2.14 μg/L at 60°C after 200 days, exceeded the Japanese limit of 2.00 μg/L. These findings highlight the potential health risks associated with Sb leaching from PET bottles, particularly under elevated temperature and low pH conditions.

Influence of trenches and soil water detection instruments on EM38-MK2 sensor readings

J.A. Edeh — 2025-05-21

Electromagnetic induction (EMI) sensors, such as the EM38-MK2, measure soil apparent electrical conductivity (ECa). The ECa values are then calibrated with soil water content, often determined by metalcontaining instruments. Such instruments and soil trenches may interfere with ECa measurements. This study established whether multi-sensor capacitance probes (small copper rings), neutron water meter access tubes (galvanized steel) and soil trenches interfere with ECa measurements by EM38-MK2 sensors. The EM38-MK2 sensor was moved towards and away from the potential interfering obstruction in a horizontal or vertical mode without re-zeroing the device. The soil trenches had no significant influence on the measurement of ECa. On the other hand, both the capacitance probes and the access tubes influenced the ECa measurement of the EM38-MK2 sensor when it was operated closer than 1 m from the two devices. Measurements of ECa were either less stable (only in the vertical mode) or lower. However, the magnitude of reduction in ECa was so small that it would likely not have any practical influence. Nevertheless, in field surveys with the EM38-MK2 sensor, a distance of at least 1 m should be kept from either the capacitance probes or galvanized-steel access tubes to avoid interferences. When encountering such devices during field surveys, it should be safe to continue measurements without additional re-zeroing of the sensor.