A growing population and a limited capacity
The City of Cape Town is investing billions of rand in upgrading the Potsdam Wastewater Treatment Works. The question residents should be asking is whether this upgrade will be sufficient to meet the growing demand for sewage treatment in the Greater Table View area.
Potsdam serves a large drainage area covering 53 suburbs and areas identified by the City. These include:
Acacia Park, Annandale Farm, Atlantis Gardens, Big Bay, Blaauwberg Strand, Blouberg Rise, Blouberg Sands, Bloubergrant, Bothasig, Brooklyn, Burgundy Estate, Century City, Dunoon, Edgemead, Flamingo Vlei, Glenwood, Joe Slovo Park, Kaapzicht, Killarney Gardens, Kleinbosch, Lagoon Beach, Marconi Beam, Milnerton, Milnerton Ridge, Montague, Montague Gardens, Monte Vista, N1-City, Parklands, Phoenix, Plattekloof Glen, Plattekloof Partial, Racing Park, Richmond Park, Richwood, Rivergate, Royal Ascot, Rugby, Sanddrift, Sandown, Summer Greens, Sunningdale, Sunridge, Sunset Beach, Sunset Links, Table View, The Stables, Tijgerhof, Tygerdal, Welgelegen, West Beach, West Riding and Ysterplaat.
For the purpose of considering future demand, a working estimate of approximately 500,000 people around 2020, rising to about 544,000 by 2030, has been used. These are estimates for discussion, not an official population count or forecast for the exact Potsdam catchment. The City should publish the actual population served and its projected growth.
The proposed Potsdam upgrade is intended to increase treatment capacity from 47 million litres per day (ML/day) to 100 ML/day. The City reported in October 2026 that the R5.2-billion project was about 80% complete, with commissioning of major components still under way.
But will 100 ML/day be enough?
What does the population mean for sewage demand?
A simple calculation illustrates the concern.
If the estimated 2030 population is 544,000 and each person generates an average of 160 litres of wastewater per day, the result is:
- 544,000 people × 160 litres = 87.04 ML/day.
- Add an illustrative 15% allowance = approximately 100.1 ML/day.
This is not an official City forecast. Actual flows depend on water consumption, commercial and industrial activity, infiltration into damaged sewers and other factors. The 15% allowance is also a modelling assumption, not a claim that this additional volume will necessarily enter the system.
Nevertheless, the calculation raises an important question. Under these assumptions, the projected demand would be virtually equal to the plant’s planned capacity of 100 ML/day.
That leaves little apparent room for unexpected increases in demand or operating problems. The City needs to provide its own current flow figures, population projections and engineering design calculations so that the public can assess the position accurately.
In an ideal world, nothing would go wrong
In an ideal world, every pump station would operate properly, every sewer would remain intact, there would be no blockages or collapses, and the treatment plant would operate at its intended capacity every day.
But that is not the real world.
The City has itself reported problems involving sewer collapses, sand entering the system, overflows and infrastructure requiring upgrades. A treatment plant cannot solve every problem in a wastewater network. Sewage must first travel through the sewer system and pump stations before it can be treated.
A failure at a critical pump station can cause sewage to back up or overflow before it reaches Potsdam. Equally, improvements to the network may allow more sewage to reach the plant, placing additional pressure on treatment capacity.
The City has reported work and planned upgrades at several pump stations, including Du Noon, Koeberg Road, Phoenix, Sanddrift East, Table View East and Table View West. The projects have different completion dates, and the City’s published timelines have changed as projects have progressed.
This matters because the wastewater system must work as a whole. Completing the treatment plant does not mean the surrounding infrastructure will automatically be ready to deliver sewage to it reliably.
High-density development adds to the concern
At the same time, the City continues to promote higher-density development and increased housing opportunities. Higher density may be necessary to accommodate a growing population, but it also increases pressure on water, sewerage, roads and other municipal services.
The City has previously acknowledged that wastewater treatment constraints can restrict development and has explored temporary packaged treatment plants in affected areas.
The question is not whether Cape Town should develop. The question is whether the supporting infrastructure will be ready before the additional demand arrives.
Approving development without a clear, funded and coordinated wastewater capacity plan risks creating a situation in which residents experience sewer overflows and environmental damage while the City tries to catch up.
The Milnerton Lagoon’s water quality has already been a major concern. Any further pressure on the wastewater system must therefore be taken seriously.
Will the network be ready in time?
The City has published different dates for aspects of the Potsdam upgrade and associated infrastructure. Its more recent updates indicate that major plant components are being commissioned, while some pump-station upgrades remain scheduled for later years, including projects extending towards 2030.
The City must clarify the difference between the date when the new treatment capacity becomes operational and the date when the entire wastewater system will be fully upgraded.
If critical pump stations or sewer infrastructure are delayed, the expected benefits of the Potsdam upgrade could also be delayed or reduced. The public needs to know what contingency arrangements are in place should these projects fall behind schedule.
Questions the City must answer
The City of Cape Town should provide clear answers to the following:
- What is the current population actually served by Potsdam, and what is the official population forecast for 2030?
- What is the plant’s actual average and peak daily inflow, and how much spare treatment capacity remains?
- What additional wastewater demand will already approved and proposed high-density developments generate?
- When will each critical pump station and sewer upgrade be completed and fully operational?
What measures will prevent sewage overflows if a pump station fails or an upgrade is delayed?
Will the full wastewater network be able to support the planned 100 ML/day treatment capacity when Potsdam reaches its intended operating level?
These are reasonable questions for residents, ratepayers and prospective property owners. They should not have to wait for another environmental crisis before receiving answers.
Planning ahead, not reacting afterwards
The Potsdam upgrade is necessary and welcome. But a R5.2-billion investment must be judged by more than the size of the project or the percentage of construction completed.
The real test is whether the plant, sewer network and pump stations can collectively handle present demand, future population growth and the additional load created by development.
The preliminary calculation presented here is not proof that Potsdam will be full by 2030. It is a warning that the City’s own planned capacity deserves to be tested against realistic population and wastewater forecasts.
Greater Table View needs a wastewater infrastructure plan that looks ahead, not one that waits for failures before taking action.
The City should publish the figures, explain the timelines and demonstrate that treatment capacity and the infrastructure feeding the plant will be ready to meet the demand it is actively encouraging.
By: Des Palm
Community Advisory Panel: Greater Table View
A CAPE of GOOD HOPE NPC INITIATIVE
