Failing sewage plants continue to pollute False Bay

While the City of Cape Town is looking at ways to stop pumping untreated sewage off the Atlantic seaboard, its largest sewage treatment works, situated near Strandfontein, is polluting False Bay by failing to treat sewage properly. 

The Cape Flats wastewater treatment works treats at least 114-million litres of sewage per day, according to the 2022 Green Drop Report released by the department of water & sanitation.

Yet, data on the department’s integrated regulatory information system (IRIS), to which all municipalities have to post monthly effluent test results from their sewage treatment works, shows the Cape Flats unit has failed to treat sewage to minimum standards for the past six years. It releases this effluent into the bay at Sonwabe Beach through a channel that runs beneath Baden Powell Drive.

The effluent is supposed to comply with minimum standards set by the department before being released into the environment. These include microbiological compliance (the amount of faecal bacteria such as E coli) and chemical compliance (chemical oxygen demand, presence of orthophosphates, nitrates, nitrites, and ammonia). The average microbiological compliance at the Cape Flats unit for 2023 was 0%, with a chemical compliance of 43%. The sewage works scored 2% for microbiological compliance in 2022, and had 0% compliance in 2021 and 2020. Its highest microbiological compliance score in the past six years was 20% in 2018. The highest chemical compliance score over the same period was 43% in 2023.

With a 200-million litre-a-day capacity, the Cape Flats unit is by far the largest sewage works in Cape Town, but it is not the only one that is failing. Data on IRIS shows that in 2023, 15 of Cape Town’s 23 sewage treatment works failed to meet microbiological or chemical compliance, or both. This does not include the marine outfalls at Green Point, Sea Point, and Hout Bay which do not treat the more than 32-million litres of sewage they pump into the sea daily. The 2024 monthly compliance results for Cape Town’s sewage treatment works do not appear to have been loaded onto IRIS yet.

Thus, read in conjunction with the latest Green Drop Report, during 2023 more than 382-million litres of partially treated or untreated sewage were released every day into the rivers, estuaries, and oceans in and around Cape Town.

Of this, 216-million litres flowed into False Bay every day, released either directly into the ocean, or via rivers such as the Eerste River. The rest flowed into the Atlantic on the western seaboard.

Coastal water quality

The available coastal water quality reports published by the City show results from weekly samples at 14 popular recreational areas in False Bay taken between October 3 and January 30. These were analysed by an independent laboratory as part of a 12-month research programme. The results show high levels of enterococci (a bacteria indicating sewage pollution) at various False Bay sites on numerous occasions.

Separately, the City’s scientific services tests water quality at 99 coastal sites every two weeks (45 sites on the Atlantic coast and 54 sites in False Bay), but in March 2023, Siseko Mbandezi, then acting mayoral committee member for water & sanitation, stated that the City’s laboratory was unable to test for enterococci since at least November 2022 “due to delays and quality challenges experienced with chemicals and consumables received”.

This appears to have begun to be resolved in November 2023 when the City started presenting enterococci results again, but enterococci data for many sites are still not available. Scientific services have, however, continued to test for E coli as a faecal pollution indicator, although World Health Organisation (WHO) guidelines cast doubt on E coli being a meaningful indicator for coastal water quality.

As a result of scientific services’ year-long gap in enterococci analysis, combined with the independent research programme at 30 recreational sites from which samples are tested at an independent laboratory, along with the Blue Flag programme’s monthly testing at 11 selected beaches, the City’s presentation of its water quality results on its website has changed a number of times over the past three months.

Previously, the City presented a 365-day rolling average for water quality at all 99 testing sites dating back to 2018, with sites graded as “poor”, “sufficient”, “good”, or “excellent”. The last such set of graded results downloaded by GroundUp in November 2023 shows chronically “poor” water quality at all 27 testing False Bay sites situated between Mnandi Beach and Gordon’s Bay. Strandfontein beach has been “sufficient” since 2019, except for being rated “poor” in 2022.

As studies have shown the predominant current in False Bay is clockwise, effluent released from the Cape Flats unit might be expected to move eastwards along the coast from Strandfontein toward Mnandi and on toward Gordon’s Bay. In line with this, the Cape Flats treatment works is mentioned as a likely pollution source in the City’s 2020 Know Your Coast report.

Forever chemicals

In addition to faecal bacteria and other disease-causing pathogens, sewage contains pharmaceutical compounds such as antibiotics, pain killers, antiretrovirals, domestic disinfectants, and a group of synthetic compounds know as per- and polyfluoroalkyl substances (PFAS). These substances   break down very slowly, if at all. Pharmaceuticals, disinfectants, and PFAS are not removed from sewage even in the best-functioning treatment plants.

Studies by University of the Western Cape senior professor Leslie Petrik and Cecilia Yejide Ojemaye have found that many of these compounds are accumulating in the flesh of fish sourced from Kalk Bay harbour. Their study, published in 2019, states: “these chemicals have a high health risk to the pelagic fish, aquatic organisms and to humans who consume them”.

A further study by Petrik and Ojemaye published in 2021, found that these persistent chemical compounds are present in seawater and sediment in False Bay, and accumulate up the food chain to seaweed, with higher concentrations found in limpets, mussels, sea urchins, sea snails, and starfish. The most common compound was the widely prescribed anti-inflammatory drug, diclofenac, as well as the antibiotic, sulfamethoxazole, raising fears of it contributing to antibiotic resistance in associated faecal bacteria released in sewage effluent.

City’s response

Mayoral committee member for water & sanitation Zahid Badroodien said the City is “ramping up its investment” in sewage treatment works “ to address a number of challenges relating to infrastructure, capacity challenges, and treatment processes”.

Badroodien said R1.8bn is estimated to be spent on extensions and upgrades at wastewater treatment works over the 2023/2024 financial year, increasing to R3bn for the 2024/25 financial year.

He said at the Cape Flats unit in particular, challenges related to the treatment process are being addressed to improve the quality of the effluent. Regarding the other sewage treatment works that release effluent into False Bay, the Macassar unit will have “a significant overhaul” and be upgraded from its 34-million litre-a-day capacity to 70-million litres-a-day.  But Badroodien said it is in an Eskom electricity supply area and affected by load-shedding. He said Eskom denied a request for it to be excluded from load-shedding.

Although the Gordon’s Bay unit functions relatively well, it is in an Eskom supply area and “load-shedding does cause some issues,” Badroodien said. Similarly, a request to exclude it from load-shedding was refused by Eskom. He said the Bellville unit, from which effluent flows into False Bay via the Eerste River, is in the final phase of a refurbishment and treatment process upgrade.

However, no mention was made of plans for the problematic Mitchells Plain wastewater treatment works, which achieved just 36% for chemical compliance in 2023, releasing at least 26-million litres of partially treated sewage into False Bay a day. Similarly, Scottsdene wastewater treatment works was not mentioned. It last achieved a microbiological compliance of 39% and chemical compliance of 32%, releasing 8-million litres of partially treated sewage a day into Bottelary River, which flows to False Bay via the Kuils and then Eerste rivers.

Similarly, Simon’s Town wastewater treatment works, although operating at only 24% of its 5-million litre-a-day,  achieved just 42% for chemical compliance in 2023, releasing 1.2-million litres of partially treated effluent directly into the bay daily.

But other sewage treatment works are also receiving upgrades and refurbishments. These are Athlone, Potsdam, Wesfleur, and Wildevoelvlei (at Kommetjie). These all release effluent either directly or indirectly into the Atlantic ocean on the western seaboard.

GroundUP/