Higher quality wastewater treatment one step closer for Waiuku

A major milestone has been reached on Watercare's $500 million Southwest Wastewater Programme, with new treatment tanks now in place ready to be installed at the Waiuku Wastewater Treatment Plant.  

Once commissioned, the upgraded facility will deliver higher-quality wastewater treatment, improve environmental outcomes and support sustainable growth across Auckland's southwest. 

The installation of the membrane aerated biofilm reactor (MABR) tanks marks a key step in the second stage of the programme, the Waiuku Boost.

The MABR tanks, together with advanced membrane bioreactor (MBR) technology and aeration units, represent the next generation of wastewater treatment.

Using naturally occurring microorganisms to break down contaminants, the system produces higher-quality treated wastewater while using less energy and a smaller footprint than conventional treatment systems.

The technology also provides a flexible, scalable solution that can adapt to future population growth. 

The Waiuku Boost builds on the successful delivery of the recently commissioned upgraded Clarks Beach Wastewater Treatment Plant and the new Clarks Beach Outfall, which are now operational. 

Franklin Ward Councillor Andy Baker says the Southwest Wastewater Programme is one of Watercare's most significant investments in Auckland's southwest, and every milestone brings us closer to delivering a cleaner, more resilient and future-ready wastewater network.  

“This investment will deliver better environmental outcomes by improving the quality of treated wastewater whilst ensuring the region has the infrastructure needed to support future growth.”

The Waiuku Boost is a key part of Watercare's $500 million Southwest Wastewater Programme.

Watercare programme delivery manager Dave Kennerley says the project team has made significant progress over the past six months, with the boost plant at Waiuku on schedule to raise quality standards in 2027. 

"The next phase will be to connect the Waiuku plant to the Clarks Beach Outfall via a 13-kilometre treated effluent conveyance pipeline, which is in design and procurement with works due to start early next year.  

“Once complete, the conveyance pipeline will enable highly treated wastewater from both Waiuku and Clarks Beach to be discharged further into a more dynamic part of the Waiuku Channel, where it will disperse more effectively, delivering improved environmental outcomes for the harbour and surrounding waterway.” 

At the Clarks Beach Wastewater Treatment Plant, enabling works are underway to deliver a permanent tidal storage facility that will unlock the full capacity of the outfall and support population growth.    

The facility will include two eight-million-litre tanks to store highly treated wastewater from both the Clarks Beach and Waiuku wastewater treatment plants before being released via the new outfall on the outgoing tide. 

The project also includes a two-million-litre emergency wet weather storage tank to help reduce the risk of wastewater overflows during extreme storm events.  

The permanent tidal storage system will be built on the site of the former oxidation pond, which is no longer needed following recent treatment plant upgrades. Enabling works are underway to allow the construction of the permanent facility, with completion expected in 2028. 

"By investing in modern infrastructure today, we're improving environmental outcomes while ensuring we can continue to support growth and meet the needs of our communities for years to come," says Kennerley.