The City of Cape Town’s R5,2 billion upgrade of the Potsdam Wastewater Treatment Works has reached 80% completion, with new treatment technology set to boost capacity, improve water quality and support the health of the Milnerton Lagoon.

Cape Town Mayor Geordin Hill-Lewis has welcomed progress on the City’s flagship R5,2 billion upgrade of the Potsdam Wastewater Treatment Works, with the installation of new treatment technology marking a significant milestone in the project.

The mayor visited the site on Wednesday 14 October, accompanied by Zahid Badroodien, Mayco member for water and sanitation, to mark the installation of new membrane bioreactor (MBR) filters capable of treating 65 million litres of wastewater per day.

The upgraded technology forms part of a broader project to more than double the plant’s treatment capacity, increasing it from 47 million litres to 100 million litres per day to accommodate Cape Town’s growing population.

Hill-Lewis said the project was progressing well, with the new reactor expected to be commissioned later this year and the full plant upgrade scheduled for completion next year.

“I was pleased to see the excellent progress on the City’s R5,2bn upgrade to Potsdam. The new reactor is on track for commissioning later this year ahead of full plant upgrade completion next year,” he said.

Improving the health of Milnerton Lagoon

The upgrade is also expected to contribute to improved environmental health, particularly at the Milnerton Lagoon, where water quality has been a longstanding concern.

Hill-Lewis said the improvements already being seen during the upgrade were encouraging and formed part of the City’s commitment to investing in sanitation infrastructure and protecting Cape Town’s waterways.

“I’m also encouraged to see how the ongoing upgrade is already contributing to improved environmental health at the Milnerton Lagoon,” he said.

The mayor added that the City had invested more than R7 billion in wastewater treatment upgrades during its current term. These investments include the ongoing upgrades at Potsdam and Macassar wastewater treatment plants, as well as the completed upgrade of the Zandvliet plant, which serves Khayelitsha and surrounding areas.

More treated water available for reuse

Badroodien said reaching the 80% completion milestone was an important achievement for the city, with the project expected to strengthen wastewater treatment capacity while creating opportunities to reduce the use of drinking water for purposes that do not require it.

“Reaching the 80% completion milestone on this major infrastructure project is an important achievement for Cape Town,” he said.

He added that the upgrade would help protect rivers and other natural environments while increasing the availability of treated effluent for businesses, farmers and recreational facilities.

The improved supply of treated effluent will allow suitable users to access reclaimed water for applications such as irrigation and industrial processes, reducing reliance on drinking water for non-potable purposes.

Key infrastructure already operational

Several components of the Potsdam upgrade have already been completed and are operational.

The new ultrafiltration plant has completed its 12-month period, which ended in June this year. The facility uses micro-screening, ultrafiltration membranes and ultraviolet disinfection to improve the quality of treated wastewater discharged into the environment and support the production of higher-quality water for reuse.

Construction of the treated effluent pump station has also been completed, allowing users in Milnerton, Century City and surrounding areas to access treated effluent for irrigation and industrial applications.

The new dewatering plant has been operational since June 2025 and is helping to reduce solids in the treatment process, contributing to improved biological stability and effluent quality.

Meanwhile, commissioning of the new inlet works and raw sewage pump station is under way, with commissioning of the membrane bioreactor treatment facilities set to follow.

Supporting a growing city

Once completed, the Potsdam upgrade will significantly increase the City’s ability to treat wastewater as Cape Town continues to grow.

The investment is intended to strengthen sanitation services, improve the quality of treated wastewater released into the environment and expand opportunities for water reuse.

With the project now 80% complete, the City says the remaining work will bring it closer to delivering a larger, upgraded treatment facility designed to meet future demand while supporting the health of local waterways.

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