Potsdam Wastewater Treatment Works (WWTW) in Milnerton, currently one of the Western Cape’s largest infrastructure projects at a cost of R5.2 billion, has reached 60% completion. Construction began in April 2023 and is progressing on schedule. It is expected to be completed in late 2027.
Once complete, the upgrade will double Potsdam’s treatment capacity from 47 million litres to 100 million litres of wastewater per day, catering for the needs of a growing city. It will also improve the quality of treated effluent released into the Diep River, which feeds the Milnerton Lagoon, and expand the supply of high-quality treated effluent for reuse by businesses, farmers and recreational facilities.
Key progress to date:
Ultrafiltration plant
As of June 2025, Potsdam entered a 12-month trial operating period. New processes (including micro-screening, ultrafiltration membranes, and ultraviolet disinfection) are in effect and being tested for enhancing treated effluent quality before discharge into the environment and supply to end-users.
Treated effluent pump station
Construction is complete and will soon be operational following final pressure testing and pipeline connections. Once active, end users in Milnerton, Century City and surrounds will be able to access supply for irrigation or industrial uses.
Dewatering plant
In operation since May 2025, with full trial operations set for October 2026. The facility is already improving biological stability and effluent quality, with noticeable reductions in solids in the treatment process.
‘We are future-proofing our city by investing in infrastructure at a rate far outpacing any other metro. In fact, over the next three years, we will invest R16.4 bn in Water and Sanitation. Furthermore, Cape Town is investing more than Joburg and Durban combined. Successfully completing two-thirds of a multi-billion Rand wastewater infrastructure upgrade project on schedule is a major milestone for Cape Town. It shows our commitment to delivering the end result on time and to high-quality standards, ensuring that critical infrastructure serves residents for decades to come,’ said Councillor Zahid Badroodien, Mayoral Committee Member for Water and Sanitation.
The present-day challenges at Potsdam WWTW, such as inflows exceeding the current design capacity, as well as sand ingress due to sewer collapses, will be addressed by the upgrades.
Major components still under construction include the new inlet works, membrane bioreactor (MBR) treatment module, raw sewage pump station and process control facility; all scheduled for completion by the end of 2027.
‘Restoring the health of the Milnerton Lagoon and improving the quality of water flowing into the catchment is a top priority for the City,’ said Councillor Badroodien.
