Cape Town has a dirty secret

Cape Town, often lauded as a premier global destination, harbors a “dirty secret” beneath its pristine marketing image: the continuous discharge of raw sewage and a complex cocktail of chemicals into its marine environment. 

Newsday recently reported that a complaint against the City of Cape Town (CoCT) has been submitted to the Department of Water and Sanitation (DWS) following repeated sewage spills, raising serious concerns about public health, marine life, and the city’s tourism future.

Cape Town’s sewage treatment isn’t coping: scientists are worried about what the city is telling the public, laid bare the dire situation.

Authored by Professor Leslie Petrik, Dr Cecilia Yejide Ojemaye, Prof Lesley Green, Dr Jo Barnes, Dr Nikiwe Solomon, and Dr Vanessa Farr, it noted that “the city discharges more than 40 megalitres of raw sewage directly into the Atlantic Ocean every day.”

“In addition, large volumes of poorly treated sewage and runoff from shack settlements enter rivers and from there into both the Atlantic and the Indian Oceans.”

Another study by Petrik and Ojemaye noted that there are three “marine outfall pipelines” that pump untreated sewage directly from toilets and drains into the ocean via underwater pipelines.

“These results, which echo findings of our previous studies in two other Cape Town marine environments, Camps Bay and Sea Point, point to major flaws in the city’s wastewater treatment plants,” said Petrik.

“Urgent action is needed to address these issues and limit the many different chemical compounds and pollutants poured into marine environments.”

According to Petrik, a leading expert on water contamination from the University of Western Cape, the problem extends beyond poor maintenance, which plagues many municipalities across the country. 

In an interview with BizNews, Petrik explained that Cape Town has a “unique situation where we are actually pumping the sewage, and let me emphasise raw sewage, from Salt River all the way to Hout Bay into our marine environment through three marine outfalls”. 

These outfalls emit raw sewage between 900 m and 1.2 km offshore. 

While designed for diffusion and dilution, “the weather doesn’t always play along and very often the wind or the tides or just the currents move the plume of sewage right onto the shore,” said Petrik.

This discharge is not intermittent; it occurs “24/7 365 days of the year ad infinitum,” said the Professor.

She said that the practice is a “legacy decision” rooted in “short-term thinking” by municipal officers who view it as “expedient to pump it out to sea.”

Despite its impact on “our touristic beaches the most,” the marine outfalls are “last on their list of priorities” for the City of Cape Town, which claims they represent only “about 5% of the total sewage,” said Petrik.

The monitoring problem

A significant challenge in managing this issue is the city’s approach to monitoring, say experts. 

Petrik criticises Cape Town for using “instantaneous plume modeling,” which “basically takes an instant in time as if there’s one plume of sewage and then they model what happens to that little puff of sewage and of course it seems to disappear.”

This contrasts with the continuous modeling used by Norwegian colleagues, who track sewage plumes for as long as they run. 

According to Petrik, the city’s testing is limited due to “very outdated” guidelines, meaning they “don’t test for the full suite of bacteria and viruses and parasites” or “the full suite of chemicals that we’re releasing.”

The CoCT told Newsday it has “extensive and arguably the most detailed marine environmental monitoring programme in the country over the last 10 years.”

This includes dispersion modelling, sediment analysis, marine species tissue sampling, biodiversity surveys, and water and pollutant testing.

According to the City, this programme has found that “no significant environmental and marine impacts have been detected or measured” beyond an initial mixing zone.

Petrik’s studies

Petrik, a nanochemist, has dedicated her work to tracing the journey of these chemicals, from start to endpoint.

She points out that sources include gardening centers that sell pesticides, pharmacies selling medication, and various soaps, detergents, and shampoos used daily by citizens. 

Crucially, current wastewater treatment plants (WWTPs) are technologically outdated, developed “about 50 or 60 years ago when these compounds didn’t even exist”. 

As a result, these compounds pass straight through the treatment plant because they cannot take them out. 

Her research has found “these persistent contaminants in almost every marine organism that we’ve tested.”

“From sea urchins, starfish, muscles, seaweed, top shells, fish…and lately, we’ve been looking at penguins, and we’re finding these compounds in everything – not just one compound, but a plethora of these compounds. ” 

The health and ecological consequences are dire. “Every disease-causing organism from the whole area from Salt River to Hout Bay is going out with that sewage,” yet “the disease organisms are not actually being measured”. 

This includes “serious microbial hazards…viral hazards and…parasites”. Petrik states, “if you hit the tide or the current at the wrong time you will be swimming in effluent”. 

Ecologically, it is difficult to find unaffected marine life as this practice has continued for over a century, but “many sites are now denuded of certain organisms”. 

The issue extends nationwide, with a “huge governance and maintenance issue across the country” and widespread “chemical pollution in South Africa”. 

While Cape Town’s drinking water quality is “still in pretty good” according to the blue drop report, other areas have water that is “absolutely not potable anymore.”

Petrik’s recent study even shows that “persistent contaminants are getting through into our drinking water in very, very low quantities, but they are there” in Cape Town.

Cape Town response

The City of Cape Town (CoCT) told Newsday that it does not claim there is no pollution beyond 500 m of marine outfalls. Rather, pollution is permitted within designated mixing zones, where it is expected to dilute to safe levels at the boundary.

The city said that decade of extensive monitoring, including modelling, sediment and tissue analysis, biodiversity surveys, and chemical testing, “beyond the initial allowable mixing zone no significant environmental and marine impacts have been detected or measured.”

The city said that a lot of the problem comes from urban rivers, impacted by informal waste, stormwater, and domestic animals waste.

To address infrastructure, the City has allocated R1.5 billion in its 2025/2026 Water and Sanitation budget to replace aging sewer infrastructure.

MMC for Water and Sanitation Zahid Badroodien told Newsday that R355 million is earmarked specifically for sewer network replacement across the city.

The City said that it reports a “steady improvement in the water quality” and the return of aquatic life.

Going forward

Fixing Cape Town’s “dirty secret” will demand a fundamental shift in public behavior, major financial commitment, and sustained political determination.

The first step, experts say, is to upgrade existing wastewater treatment plants. While the city claims there are currently no ways to treat certain waste streams, plans are underway for a 4A reuse plant.

The real obstacle, however, is cost: many municipalities simply do not want to invest in treating effluent to potable standards.

Some municipal efforts are moving forward, but tackling marine outfalls may not happen until around 2050. 

In the meantime, Petrik advises residents to reduce their own chemical use at home, avoid unnecessary medication, and limit antibiotics wherever possible. 

For those wanting cleaner waters now, she suggests swimming along the far South Peninsula.

The CoCT did not respond to other questions from Newsday.