Multi-year interventions to improve Milnerton Lagoon water quality, steadily progressing

04 November 2025

Extensive infrastructure upgrades, proactive maintenance and environmental monitoring continue to form part of the City’s long-term plan to restore the Milnerton Lagoon and surrounding catchment.

At a public meeting held on Wednesday, 29 October 2025, residents were briefed on the latest progress in the City of Cape Town’s multi-pronged programme to tackle pollution in the Milnerton Lagoon. The programme includes extensive sewer and pump station upgrades, improvements at the Potsdam Wastewater Treatment Works (WWTW), a strengthened proactive maintenance schedule and continued environmental monitoring, including air and water quality testing.
 
‘The City thanks residents for their ongoing engagement as we roll out these multi-year interventions. The reports presented show steady progress being made, which reflects our commitment to restoring the ecological health of the Milnerton Lagoon and the wider Diep River catchment,’ said Councillor Zahid Badroodien, Mayoral Committee Member for Water and Sanitation.

Ongoing upgrades and maintenance
The City’s Water and Sanitation Directorate continues to implement both short- and medium-term interventions to ensure the optimal functioning of the sewer network and pump stations in the catchment.
 
Sewer network maintenance
• Proactive sewer cleaning and jetting are done every three months, with over 12km of sewer lines cleaned between May and October 2025.
• Manhole integrity inspections and proactive maintenance are ongoing, helping to reduce blockages and overflows.
• Monthly sewer blockages have decreased in the Lower Diep and Rietvlei catchment from 4 270 in October 2024 to 3 460 in September 2025, indicating a sustained downward trend.
 
Proactive network rehabilitation projects
Recent sewer rehabilitation projects are extending the life of ageing infrastructure:
• Montague Gardens: 1 850m of sewer pipeline rehabilitated (R6,9 million)
• Milnerton: 545m rehabilitated along Omuramba Road and Racecourse Road (R3,9 million)
• Century City (planned 2025/26): 5,3km of pipe relining (R18,8 million)
• R27 (Bayside Mall): Repairs to a structurally deteriorated 165m sewer section are under way, with lining scheduled for early November 2025 to restore the pipe’s integrity. An investigation on the larger sewer network in the area is also under way and includes this section, which will inform the bigger capital project to be implemented as part of the future pipe replacement programmes in the area.

Pump station telemetry
All 112 reticulation pump stations across the Blaauwberg region are equipped with telemetry systems. Within the Potsdam catchment, 56 stations are continuously monitored for early fault detection.
 
Addressing pump station failures
An analysis of 160 pump station failures between October 2024 and September 2025 shows that the majority of overflows were caused by rags (34%), stormwater entering the sewer system (19%), and pump overheating linked to this excess inflow (19%).
 
• Koeberg Road experienced 45 failures, mainly due to stormwater ingress (51%) and rags (29%).
• West Beach recorded 25 failures, with rags responsible for 45% and stormwater ingress for 12% of incidents.
• Phoenix and Dunoon each experienced 10 failures, with rags causing eight and stormwater ingress causing two at both sites.
 
To address these recurring issues, the City has prioritised several upgrades to strengthen infrastructure and prevent future overflows:
 
• Koeberg Road PS: A new sand trap and screening facility was commissioned in September 2025 (R61 million). Since the sand trap has been commissioned, pump station overflows are contained within the sand trap. The next phase, a capacity upgrade, will begin in 2026 and is due for completion by December 2028 (R136 million).
• Dunoon PS: The screen upgrade and further reconfiguration and overflow pond improvements are targeted for June 2026.
• Phoenix PS: Preliminary design is under way, with construction planned to start in July 2027 and completion expected by June 2028 (R76,9 million).
• Sanddrift East PS: Upgrade completion is anticipated by December 2027 (R65 million).
• Table View East PS: The overflow pond has been reinstated and a basket screen installation is in progress. A full upgrade is scheduled for August 2030 (R78,7 million).
• Table View West PS: Scheduled for completion in June 2030 (R36,6 million).
• West Beach PS: While no upgrade is needed to this facility because its capacity is adequate, City teams continue to monitor and clear foreign objects that block this pump station as swiftly as possible. 
 
Major upgrades at Potsdam WWTW
The major Potsdam Wastewater Treatment Works (WWTW) upgrade, which started in April 2023 at R5,2 billion, has passed 60% completion and is currently on track for completion in 2027/28.
 
Sections of work currently under way:
• Ultrafiltration Works: All civil construction has been completed. The mechanical and electrical installations are finished, and the units are now in their Trial Operations Period (TOP). Staff training has begun, including sessions on the new ultraviolet (UV) disinfection system,  microscreens and ultrafiltration systems.
• Dewatering: The new dewatering plant has been completed and commissioned, featuring 16 presses (eight waste-activated sludge and eight primary sludge presses). The facility is currently in its pre-TOP including staff training.
• Inlet Works: Construction is progressing well, with major mechanical equipment installed and commissioning on schedule.
• Membrane Bioreactor (MBR) Section: Work is on track, with completion and commissioning planned for 2027/2028.
 
Once fully commissioned, the upgraded plant will deliver major improvements to effluent quality and environmental performance.
 
Air quality monitoring: hydrogen sulphide (H₂S)
Between 6 June and 19 October 2025, the temporary air quality monitoring station at Woodbridge Island detected brief odour events. However, none exceeded the World Health Organisation’s 24-hour average guideline. Plans are under way to relocate the station permanently and to make H₂S readings publicly accessible through the South African Air Quality Information System (SAAQIS).
 
Expanded cleansing operations in Milnerton
To further support the lagoon clean-up efforts, Urban Waste Management has intensified its operations across Milnerton and Joe Slovo:
• Daily cleaning: Street sweeping, litter-picking and green litter bin servicing.
• Seasonal deployments: Additional Expanded Public Works Programme (EPWP) staff during winter and festive periods to clear riverbanks and beaches, prevent blockages in stormwater channels and manage high waste volumes.
• Informal settlements: Weekly refuse collection, seven-day cleaning services and door-to-door bag distribution.
• Challenges addressed: Illegal dumping, damaged bins, canal access constraints and outdated dwelling counts are being managed through additional mechanical interventions and closer coordination with ward councillors.
 
These collective improvements are a key to the City’s broader strategy to improve the Milnerton Lagoon ecosystem and overall water quality in the Diep River catchment.

End

Published by:
City of Cape Town, Media Office