Watercare’s Central Interceptor project is the largest wastewater infrastructure project in New Zealand history and will leave a legacy of a cleaner environment for the people of Tāmaki Makaurau for the next 100 years.

It consists of a main 16.2‑kilometre‑long tunnel (or interceptor) running from Point Erin Reserve, Herne Bay to the Māngere Wastewater Treatment Plant. Two branch sewers intersect the main tunnel, collecting combined wastewater and stormwater flows from western suburbs such as Mount Roskill, Mount Albert and Blockhouse Bay. The flows transfer from the shallow existing wastewater network to the much deeper Central Interceptor tunnel below via a series of shafts. Cascade shelves made from concrete or reinforced fibreglass break the energy of the falling wastewater as it transfers into the tunnel and travels by gravity to the treatment plant for processing.

A major new pump station at Māngere sends flows from the tunnel to the treatment plant.

Once the project is completed in the coming years and future connections are made, the combined infrastructure projects will significantly reduce wet weather overflows into streams and beaches. The improved water quality will mean fewer black flags on Auckland Council’s Safeswim website and enormous environmental benefits for everyone to enjoy.

Click through to the below photo galleries to view an in-depth look at the Central Interceptor from the lens of documentary photographer Simon Runting.