Auckland’s NZ$1.66bn (€850m) Central Interceptor – New Zealand’s largest-ever wastewater infrastructure investment – is now fully operational.
The southern half of the tunnel went live in early 2025, preventing an estimated 741,000m3 of wastewater and stormwater from overflowing into the environment by July 1 this year. With the northern section now in service, the whole system is operational.
Running from Point Erin in Herne Bay to the Māngere Wastewater Treatment Plant, the 4.5m-diameter tunnel sits between 15-110m below ground and passes beneath the Manukau Harbour. It has a total of 19 shafts.
Together with its link sewers in Mt Roskill, Blockhouse Bay and Mt Albert, it captures and transfers wastewater and stormwater flows that would otherwise contribute to wet-weather overflows.
Watercare chief executive Jamie Sinclair said completion of the 16.2km Central Interceptor was a transformative moment for Auckland.
“The Central Interceptor is a game changer for our city that will deliver lasting environmental, community and growth benefits for Aucklanders,” he said.
“This project is at the heart of our commitment to improving water quality across the region. Bringing together world-class engineering, long-term planning and strong partnerships, it delivers benefits for Aucklanders now while enabling a new generation of projects that will further reduce wastewater overflows and make a real difference to the health of the Waitematā Harbour and other waterways into the future.”
He added that the Central Interceptor provided the backbone for future projects that would further improve environmental performance, increase network resilience, and support Auckland’s growth.
The first of these projects, the Herne Bay Collector, is under way. The wastewater tunnel will connect to the Central Interceptor when completed and contribute to further reducing wet weather overflows.
Ghella Abergeldie Joint Venture began construction in 2019. Despite challenges including the Covid-19 pandemic, major weather events and unprecedented inflationary pressures, the team delivered the project on schedule and close to its original budget.
