One river running through South Africa’s richest province is so polluted it is killing people
Once a shimmering centerpiece of the area, Centurion Lake in Gauteng has become, in the words of some local residents, “a pungent ghost town that nobody wants to go near.”
Standing on the banks of what was once a bustling tourist attraction, with vibrant restaurants and shops, the overwhelming smell of raw sewage now dominates the scene.
Lake Centurion is now so filled with sediment and pollution that it no longer functions as a proper lake. Incoming water from the Hennops River is heavily contaminated with sewage, plastic, and toxins.
The Hennops River, spanning just under 100 kilometres from its source in Kempton Park to its confluence with the Crocodile River near Hartbeespoort Dam, plays a vital role in the region’s ecosystem.
It begins at the meeting point of the relatively clean Sesmylspruit and the severely polluted Kaalspruit/Olifantspruit.
What happens at these headwaters critically impacts the downstream systems, including the Crocodile River and Hartbeespoort Dam.
Water expert Professor Anthony Turton told BusinessTech that Hennops pollution has been a persistent problem, driven by industrial runoff, long-standing sewage discharge, and poor wastewater management, issues dating back before 1994.
As a result, adjacent properties like Centurion Mall have suffered falling real estate values and tenant losses.
To date, the river continues to carry its pollution toward Hartbeespoort Dam, amid controversial claims of radionuclide contamination near Pelindaba, which authorities have denied.
Illegal sand mining, especially upstream, has exacerbated sediment buildup, contributing to the lake’s degradation and reflecting a broader national problem.
On top of this, densely populated surrounding areas like Tembisa, Ivory Park, and Olifantsfontein lack essential services such as sanitation, waste removal, and stormwater control.
As a result, the Hennops is continuously burdened with raw sewage, industrial effluent, and litter.
State of the river
A major pressure point is the Olifantsfontein Wastewater Treatment Works (WWTW). Designed to handle 110 million litres per day, it is routinely overwhelmed, sometimes processing nearly double its capacity.
This results in tens of millions of litres of untreated or poorly treated effluent flowing into the river daily.
“The simple truth is that WWTWs are slowly rendering the drinking water of the country unusable,” said Turton.
Additionally, the process of sedimentation was accelerated after illegal sand mining operations gained a foothold in the areas that feed the Olifantsfontein Wastewater Works.
“This is now a material factor in the dysfunction of the Ekurhuleni Water Care Company plant, along with fats, oil and grease, and of all things, clogging of the machinery,” wrote Turton for the Daily Maverick.
The river’s degradation is further accelerated by:
- Illegal dumping of industrial waste and rubble,
- Poorly managed stormwater systems and illegal waste sites,
- Erosion caused by sand mining and vegetation loss,
- High E.coli counts, often in the millions (vs. the safe limit of 200 mg/l), from the pollution and agricultural runoff,
- High conductivity levels indicate chemical pollution,
Invasive plants, unmanaged flooding, and a lack of large-scale community involvement have also undermined rehabilitation efforts.
Very broadly, these issues have made the Hennops River now one of the most polluted waterways in Gauteng.
A recent study by Thabiso Letseka from the University of the Witwatersrand’s Faculty of Science confirmed many fears about the dangers of the river, finding it critically polluted and unfit for drinking, irrigation, or recreation.
Using chemical, microbiological, microplastic, and ecotoxicological analyses, the researcher discovered dangerously low dissolved oxygen levels, pointing to sewage contamination from ageing infrastructure and overloaded treatment plants.
E. coli was consistently high across all sites, indicating widespread faecal pollution. Microplastics, mainly textile fibres, and pharmaceutical residues were also present.
“The Hennops river continues to be in a vulnerable state as a result of the ongoing pollution and is incapable of sustaining the lives of aquatic biota, and the consequences are increasingly becoming dire,” wrote Letseka.
Current interventions, such as litter traps and insect-based water hyacinth control, are helping, but Letseka warned that they only address symptoms.
“Most of the focus should be upstream to stop the pollution from the source.” Without intervention, more wildlife may perish, especially during dry months.
In early 2025, parts of the river turned green due to algal blooms following regional flooding. The Council for Scientific and Industrial Research (CSIR) has explained that cyanobacteria is a group of blue-green algae that occur in “highly visible blooms mainly in aquatic ecosystems that can be toxic to fish and other species and pose serious human health risks”.
The phenomenon, known as eutrophication, is described by the CSIR as “nutrient enrichment that may lead to an increase in harmful algae in an aquatic system”, often resulting from agricultural runoff and wastewater discharges.
The South African Human Rights Commission (SAHRC) found that local mismanagement of wastewater treatment plants has been key in the severe pollution of rivers like the Hennops, threatening ecosystems, health, and livelihoods.
Despite decades of complaints and directives, the SAHRC said that the government has failed to act, violating constitutional rights to a safe environment and proper water services.
“Without sounding dramatic, South Africa is slowly committing ecocide – national suicide by poisoning its own drinking and crop production water,” Turton previously told BusinessTech.
Grassroot interventions
Several non-profit organisations are working to rehabilitate the Hennops River through large-scale clean-ups, education, restoration, and partnerships.
For example, founded in 2019, Hennops Revival has led over 700 clean-ups, removing an estimated 4.5 million kilograms of waste.
These efforts have created over 8,000 work opportunities and mobilised volunteers for more than 24,000 hours.
The group also uses stormwater nets, enzyme treatments to reduce faecal pollution, and school programs to promote environmental awareness.
Sister organisation Deep Water Movement extends this mission across South Africa, empowering communities with education, waste exchange hubs, and pollution prevention initiatives.
Another group, Fresh (Fountain River Environmental Sanctuary Hennops), founded by Willem Snyman, focuses on long-term ecological rehabilitation, including support for wastewater treatment, wetland creation, and anti-dumping efforts.
Among other interventions, for over a decade, Fresh has employed teams from Tembisa to work upstream along the Kaalspruit, erecting traps that tons of rubbish and preventing thousands of tons of litter from washing further down to the Hennops.
Speaking about longtime resident Coert Steynberg, who had passed away following consumption of water from the Hennops River in late 2024, Snyman said that “the river has gone from such a vast life-giving force to something that is taking lives now.”
Snyman said that heavy pollution has wiped out most aquatic life in the Hennops River, making contact with the water unsafe.
Sewage contamination has also affected groundwater in the area, with E. coli levels having reached in their millions.
This severe pollution poses a major health risk, especially since the water flows into Hartbeespoort Dam, which irrigates crops feeding millions.
Ways forward
In June 2024, the City of Tshwane and the Department of Water and Sanitation signed a memorandum of understanding.
Among the priorities it promised was tackling pollution in the Hennops River, and there have been clean up campaigns.
As pollution in South Africa’s rivers worsens, advocacy group WaterCAN is calling for urgent accountability and reform.
WaterCAN executive director Dr Ferrial Adam said that endemic municipal mismanagement and lack of accountability have exacerbated the crisis.
“There is not enough enforcement to arrest all polluters, people dumping… and hold them accountable,” Adam told BusinessTech.
“The cry that they do not have money makes me so angry because it is not about no money, it is more about mismanagement, poor/incorrect priorities. For nonsense, they can find the money in an instant.”
WaterCAN wants individuals, including mayors and municipal managers, to be prosecuted for ongoing pollution and failure to enforce environmental laws.
It opposes blanket charges against municipalities, advocating instead for personal legal responsibility.
The organisation is also building a nationwide citizen science network to monitor water quality and plans to pursue litigation to force compliance.
But Adam says lasting recovery requires functional municipalities, ring-fenced budgets for water and sanitation, and action against corruption, including tackling the so-called “water tank mafia.”
Public education and urgent infrastructure repairs are equally crucial. Without them, WaterCAN warns, meaningful change remains out of reach.
Water expert Professor Anthony Turton supports the group’s stance. While he notes that “wastewater policies in South Africa are mostly OK,” he stresses that “none are being enforced.”
“Regardless of the ruling party, it’s the Three D’s—deny, deflect, and demonise,” he said.
“The most viable solution is the use of SPVs to ringfence finance, and PPP models to manage dysfunctional sewage works,” said Turton.
He believes the upper Hennops is ideal for piloting tradable water credits, where measurable improvements in water quality generate credits that can be traded as assets. “This generates revenue but also gives regulators direct control.”
Large investment and insurance firms in the area could use their CSI budgets to support this.
While some South African officials are “enthusiastic” about the idea, they want a working example first. “The Hennops will become the proof of concept,” Turton insists.
He said that municipal, provincial, and national authorities are not doing enough to maintain and regulate wastewater treatment systems.
“The municipalities are all in distress. ERWAT could play a major role, but is also distressed. Everyone passes the buck,” said Turton.
“The NGOs do a great job, but they are seen as a risk to vested interests such as illegal sand mining, so they are sabotaged. It would be good to support the NGOs, as that have deep knowledge of the system.”
While structural fixes will take time, Turton calls for urgent collaboration. “The upper Hennops has all the right sorts of players already there. It just needs political will and a champion to pioneer the concept.”
Hennops Revival also recommends actions for the Hennops River catchment, including improving infrastructure and waste management, strengthening stormwater and pollution control, promoting community involvement, and reducing plastic use while conserving water.
On 26 May 2025, the Tshwane, Johannesburg, and Ekurhuleni metros announced that they had formed a joint task team to rehabilitate the polluted Kaalspruit Catchment.
They said that this collaborative effort will align plans, secure funding, and involve the Gauteng Department of Environment to tackle urbanisation-driven pollution and restore the health of the water system.
“Since 2019, a dedicated task team has worked consistently to reduce flooding risks, remove debris, and engage local stakeholders in improving the Hennops River and Centurion Lake,” said city spokesperson Lindela Mashigo.
“To suggest that local government is apathetic or disengaged misrepresents ongoing initiatives and community partnerships already in place.”
The spokesperson added that collaboration with civil society is vital but must respect environmental laws.
The City said acted within NEMA and Water Act frameworks, and compliance should not be seen as obstruction, adding that they are open to constructive engagement.
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