Eight years after the height of the drought, City may finally get a desalination plant

Cape Town is contemplating a R5 billion desalination plant, slated to produce up to 70 million litres of water daily. This component of the City’s New Water Programme is pitched as a climate-resilient solution to future droughts. Yet, the project has drawn skepticism from water and conservation experts, who argue that the environmental and financial costs may outweigh the benefits.

The proposed plant in Paarden Eiland would employ reverse osmosis (RO) technology to extract potable water from seawater, complemented by UV oxidation to address local contamination risks. Zahid Badroodien, the City’s Mayoral Committee Member for Water and Sanitation, describes the initiative as “state-of-the-art,” and touts the department’s paid experts as proof.

However, critics question the feasibility of the venture, pointing to Cape Town’s polluted coastal waters and the economic inefficiencies of desalination. Leslie Petrik, an emeritus professor at the University of the Western Cape, has warned in interviews with various publications that desalination is far costlier than alternatives such as wastewater recycling or groundwater extraction. Producing potable water via desalination costs R9 per kilolitre—nearly double the cost of reusing treated wastewater.

Her 2017 study on the available opportunities highlighted the problems with bacterial load and toxic chemical load in the water, reflecting her recent comments on the City’s century-long refusal to stop dumping untreated sewage into the bay. Petrik also highlighted significant environmental risks. The plant’s proximity to Cape Town’s polluted harbour and contaminated rivers, such as the Black and Diep, raises concerns over water quality. Moreover, brine—the concentrated saline byproduct of the desalination process—could exacerbate marine pollution if discharged back into the ocean, harming ecosystems and further tainting the intake water.

From the study:

“Apart from the high microbial load being discharged into the ocean daily, the complexity and toxicity of chemicals that are being disposed into the City’s sewage are imposing a growing chemical pollution risk to the nearshore coastal environment, and thus to the desalination plant’s intake water. Given the diversity of contaminants shown to be ubiquitously present in the intake water in such close proximity to the marine outfall in Green Point, it is probable that the water recovered from desalination may still be contaminated with traces of complex pollutants after the reverse osmosis process, as Patterton’s study also showed. This probability represents a public health issue. Drinking water supplied by the seawater desalination plants should be regularly screened for its toxicity”

Patrick Dowling of the Wildlife Environment Society of South Africa (Wessa) echoes these concerns, cautioning that increased salinity levels could disrupt marine life, including fish larvae and plankton. He describes the plant’s projected output—just over 10 litres per person per day—as modest compared to its steep R5 billion price tag.

Kevin Winter of the University of Cape Town’s Future Water Institute urges the City to prioritize more cost-effective measures, such as improving wastewater treatment, harvesting rainwater, and managing invasive plant species. “Desalination should be a last resort,” Winter asserts, emphasizing the high energy demands and operational costs of RO systems. He suggests postponing large-scale investments until the technology evolves in efficiency and affordability.

And this is not simply an academic matter. In 2019, Quality Filtration Systems (QFS), owner of the V&A Waterfront desalination plant, terminated its contract with the City of Cape Town and promised to sue for breach of contract and damages QFS claims the City misrepresented the quality of seawater in its tender, leading to higher-than-expected costs for treating and desalinating water. The plant had already been dormant for months due to contaminated seawater. Mediation between the two parties concluded on 8 April 2019 without resolution.

The City’s demonstrated hostility to scientific critics of their environmental policies reflects similar unethical and dishonest approaches to environmental impact research elsewhere in DA jurisdiction, such as in Drakenstein, where a R20 million EIA for toxic air pollution stemming from the proposed waste to energy plant, and in Cape Town, the aforementioned scientists have received endless bashing from City employees and hangers-on of the governing party for their criticism of the administration’s complacency over seawater pollution.

Still, some see the project as unavoidable. Anthony Turton, a water resource management expert, argues that Cape Town’s growing population and economic aspirations demand a stable water supply.

Naturally, the DA insists on incentivising the maximum possible influx, driving up housing prices in a desperate attempt to prevent the necessity for budgetary austerity, leaving the end of the housing bubble as a problem for future administrations.

The City defends its desalination plans as a prudent investment in climate resilience. Badroodien emphasizes that extensive feasibility studies and public consultations will guide the project’s design, ensuring adherence to global best practices. While acknowledging the challenges, he argues that the cost of inaction—severe water shortages and economic disruption—could be far greater.

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