Sewage and contaminants in Cape Town sea

Professor Leslie Petrik, Department of Chemistry, University of the Western Cape

The City of Cape Town discharges a large volume of untreated or partially treated sewage effluent into the ocean via outlets located around the Cape Peninsula. This sewage contains a high degree of contaminants, including chemicals, pesticides, perfumes and disinfectants, which up until recently could not be accurately measured.

Many contaminants are able to pass through wastewater treatment systems without adequate removal, as well as through systems used in desalination plants, or through treatment systems for wastewater reuse. To make matters worse, 80% of wastewater treatment plants are only marginally functioning, a situation that deteriorated further with the concentrations of effluent caused by water use restrictions during the Cape’s recent drought.

Risks to humans

Uncertainty over the magnitude of risk of human exposure to these contaminants means it is necessary to measure their levels in the ocean, as well as in potential sources of potable “reclaimed” water, such as desalinated sea water.

Senior scientists from the University of the Western Cape, the University of Cape Town and Stellenbosch University, in partnership with others from the University of Stavanger and the International Research Institute of Stavanger in Norway, are conducting a substantial study of the seasonal behaviour of the effluent outfall plumes around Cape Town and the current outfall flow rate impacts, neither of which have previously been studied. The areas being studied are Table Bay, the Atlantic seaboard and False Bay.

There is also a clear need for democratic participation in decision-making on the issue, for urban planners to be on board and for the public to become more aware of the consumer choices they make in respect of the purchasing and disposing of harmful chemicals and pharmaceuticals, which have direct effects on long-term wellbeing of humans and marine species.

Subscribe to the M&G

These are unprecedented times, and the role of media to tell and record the story of South Africa as it develops is more important than ever.

The Mail & Guardian is a proud news publisher with roots stretching back 35 years, and we’ve survived right from day one thanks to the support of readers who value fiercely independent journalism that is beholden to no-one. To help us continue for another 35 future years with the same proud values, please consider taking out a subscription.

Related stories


Subscribers only

ANC’s rotten apples on the chopping block

Now that the NEC has finalised its step-aside guidelines for those facing corruption charges, a swathe of officials will struggle to cling to their positions

The race elephant lurking in the DA’s ‘laboratory’

Tony Leon’s comments calling Mmusi Maimane an ‘experiment’ have lifted the lid on what disgruntled black leaders describe as insidious racism and a refusal to hold racists to account

More top stories

More ethnically diverse bone marrow donors needed to save lives

The myth that regenerative stem cells are body parts has led to donor reluctance

Khaya Sithole: The real weapons of mass destruction

Ratings agencies and derivatives caused the housing bubble, but where does the next financial crisis lurk?

Analysts expecting another attack ‘in the next few months’ in...

The extremist insurgency in Mozambique has been an ongoing threat since 2017. SADC needs to act now, say analysts

SIU probes how master of the high court fleeces the...

While the SIU delves into dozens of allegations of fraud, corruption and misconduct against officials at the master of the high court, many families have been left destitute after the death of their loved ones.

press releases

Loading latest Press Releases…