Central Interceptor flows under Hillsborough2 min read

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A major milestone has been reached in Auckland’s largest wastewater project, with the Central Interceptor now flowing beneath Hillsborough.

Watercare’s Central Interceptor project has passed a historic milestone with the southern half of the 14.7km tunnel (Blockhouse Bay south to Māngere Wastewater Treatment Plant), going live in February. Mayor Wayne Brown gave an order to start up the giant pumps, sending wastewater flows through the tunnel to the treatment plant, at a rate of 1,200 litres per second.

Wastewater is now actively flowing under Hillsborough, including areas near Keith Hay Park, Hillsborough Road, Frederick Street and beneath a section of Manukau Harbour.

“It’s a significant milestone for Aucklanders and a huge engineering feat for the team who have been working for the past six years. I look forward to the Central Interceptor project being completed next year to fully realise the benefit, including an 80% reduction in wet weather overflows and improved water quality.”

Watercare Chief Programme Delivery Officer, Shayne Cunis, says that getting the southern half of the tunnel running early was always the goal. “This is a huge result. It is rare for a major infrastructure project to be delivered safely, economically and on time. We didn’t want to wait until the project was finished at the end of 2026 before getting the southern tunnel going. We’ve done that despite everything that’s been thrown against us, including Covid, major storm events and unprecedented inflation for modern times.”

The southern section’s activation has improved wastewater network resilience, reducing strain on aging infrastructure, like Hillsborough’s Pump Station 23 in Frederick Street, and eliminating flows under Manukau Harbour.

The Central Interceptor is part of Watercare’s $13.2 billion investment in water and wastewater infrastructure over the next decade. Full completion is expected in 2026.