Update: 19 August 2025, 10pm
The City of Cape Town has responded to a recent University of Cape Town study claiming that Hout Bay’s marine environment is being threatened by pharmaceutical and personal care products (PPCPs).
The research, which detected chemical compounds in mussels far from the marine outfall and river mouth, raised questions over wastewater management, pollution monitoring and potential human health risks.
Eddie Andrews, the City’s Deputy Mayor and Mayoral Committee Member for Spatial Planning and Environment, emphasised that the issue of removing contaminants of emerging concern (CECs) is a global challenge.
‘Wastewater treatment works globally do not generally effectively remove contaminants of emerging concern from sewage, irrespective of the level of treatment,’ he said, adding that advanced technologies exist but are costly and not always practical at scale.
Andrews highlighted that even Cape Town’s most modern treatment works cannot completely remove trace pharmaceuticals. The City has conducted feasibility studies on replacing existing marine outfall pipelines with new treatment works, but no final decision on timing has been made.
He also questioned the methodology of the UCT study, saying it did not assess volumes of PPCPs discharged and relied solely on mussel tissue samples. ‘This study cannot draw conclusions as to the source of the contaminants or the extent of the impact zone of the marine outfall,’ Andrews said.
Zahid Badroodien, the Mayoral Committee Member for Water and Sanitation, confirmed the City’s ongoing commitment to upgrading wastewater systems.
‘The Hout Bay marine outfall currently operates within its design parameters and complies with national discharge regulations,’ he said, while acknowledging that emerging contaminants are a global challenge.
The City stressed its transparency and public engagement through Permit Advisory Forums (PAFs), where independent environmental monitoring data is shared and discussed. The next PAF is scheduled for 22 August 2025, with the latest monitoring results to be presented.
Infrastructure issues in Hout Bay remain a concern, particularly in informal settlements like Imizamo Yethu. Factors such as unplanned densification, illegal sewer connections, stormwater cross-connections, and misuse of the sewer network contribute to overflows.
The City has implemented short-term interventions, including proactive cleaning, education campaigns, leak detection, and upgrades to pump stations. Medium- and long-term plans include possible pipe enlargements, inline treatment studies, and master plan upgrades expected in future financial years.
While acknowledging the presence of CECs in mussels, the City noted that current evidence does not indicate significant risk to humans or the environment. Andrews pointed out that globally, pharmaceutical accumulation in marine life is widespread and that establishing safe levels is still an evolving science.
‘At a dry weight concentration of 43 nanograms per gram of mussel tissue, it would take the tissue of around 3 million mussels to equal a single Panado,’ he said, suggesting that the study’s conclusions were speculative.
The City reaffirmed its commitment to reducing sewer spills and improving water quality, highlighting a R1.25 billion investment in sanitation infrastructure this year, with R355 million for pipe replacements and R241 million for pump station upgrades.
Regular monitoring of coastal waters and rivers continues, with public warnings issued around stormwater outflows and river mouths following rainfall events.
‘We remain committed to science-based decision-making and inclusive public engagement,’ Andrews said. ‘The Hout Bay marine outfall is not being disregarded, and we will act on reliable data as it becomes available.’
A new University of Cape Town (UCT) study has revealed that Hout Bay’s marine environment is seriously threatened by pharmaceutical and personal care product compounds (PPCPs) that persist and bio-accumulate in marine life, even kilometres away from pollution sources, Cape {town} Etc reports.
The findings, published in Environments, raise questions about sewage management, environmental monitoring and public health in one of Cape Town’s most iconic coastal areas.
The research team, led by UCT’s postdoctoral research fellow Dr Cecilia Ojemaye, detected a range of PPCPs in mussel tissue samples collected at significant distances from the marine outfall and the Hout Bay River mouth.
These compounds, residues from common medications and personal care products, enter the marine environment through human excretion, wastewater discharge and improper disposal.
‘The presence of these compounds in mussels is a red flag,’ said Dr Ojemaye. ‘Mussels are sentinel organisms, they filter the water and accumulate pollutants, which means they are telling us a story about the health of the entire marine ecosystem.’
The study indicated that the pollution plume from Hout Bay’s sewage discharges extends far beyond the immediate outfall area, contradicting previous assumptions that contaminants disperse quickly and harmlessly.
Instantaneous modelling of bacterial indicators, such as enterococci, has been used in the past to justify the safety of marine outfalls, but researchers say this approach fails to capture the long-term build-up of persistent chemicals.
‘This is not a case of “dilution is the solution to pollution”. These contaminants don’t just disappear, they spread settle, and accumulate in marine life, creating an extensive and ongoing impact zone,’ said Ojemaye.
Hout Bay’s sewage system has long been a source of contention between residents, the municipality and environmental groups. Historical municipal decisions, including the choice of a marine outfall over land-based treatment, have been unpopular with local communities.
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‘The City (of Cape Town) has not provided Imizamo Yethu with adequate sanitation infrastructure for decades, leading to exceptionally high faecal content in the Disa River,’ said co-author of the study, Professor Lesley Green, a professor of earth politics and director of Environmental Humanities South at UCT.
Green urged Cape Town to take a lead from the Minister of Environmental Affairs, who ‘committed the country to protect marine biodiversity when he signed the UN Oceans 2025 pledge in Paris in June this year.’
The study claims that the marine outfall services about half of Hout Bay’s population, making it a significant source of chemical and microbial contamination. While the Hout Bay River also carries pollutants into the bay, the design and operation of the outfall itself contribute heavily to the problem.
Researchers warn that the situation poses both ecological and potential human health risks, especially if contaminated mussels and other shellfish are consumed. The bay lies within a marine protected area, making the findings particularly concerning for conservation efforts.
Beyond environmental damage, the team’s research points to wider public health implications, including the possible spread of antimicrobial resistance through contaminated marine environments.
‘We urgently need to understand whether faecal coliforms in Hout Bay are carrying antimicrobial resistance genes. If so, this could have consequences for human health that extend far beyond our coastlines,’ said Ojemaye.
The study calls for a multi-pronged response, including investment in upgraded wastewater treatment, reduction of harmful chemical usage and stronger regulations on pollutant discharge.
‘This is especially critical in light of emerging challenges like the COVID-19 pandemic, which saw increased chemical usage, and South Africa’s ongoing energy crisis, which impacts wastewater management,’ said Ojemaye.
Researchers argue that replacing marine outfalls with land-based treatment facilities should be a priority. Such systems can not only remove pollutants more effectively but also produce renewable energy and recover valuable resources from wastewater.
‘Hout Bay’s pollution problem is not unique, but it is urgent,’ said Professor Green.‘This is an opportunity for innovation and collaboration. With the right technologies and political will, we can turn wastewater from a hazard into a resource.’
The research team stresses that while further studies are needed to map the pollution zone’s full extent and understand the risks of consuming contaminated seafood, immediate mitigation measures should begin without delay.
Green said, ‘This is not just about science, it’s about protecting livelihoods, ecosystems and the health of our communities. If we wait until the damage is irreversible, it will be too late.’
‘The study is a wake-up call for Cape Town, urging both policymakers and the public to face an uncomfortable truth: the city’s marine environment is absorbing the cost of inadequate wastewater management. Without urgent intervention, the toxic tide will keep rising.’
The City was contacted for comment but has yet to respond.
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