Central Interceptor

Under Delivery
Central Interceptor

The Central Interceptor is an expansion to the existing Auckland Wastewater network, aiming to increase capacity and reduce overflow. 

The project scope includes: 

  • construction of a 14.7 km long tunnel with a 4.5 m internal diameter
  • two 3.2 km long sewers, at a maximum depth of 70 m
  • multiple drop shafts and access shafts
  • expanding existing connecting sewers, chambers, control facilities and air treatment facilities, and
  • construction of a wastewater pumping station.

The project is being delivered through a Ghella Abergeldie Joint Venture.

An additional 1.5 km Grey Lynn to Point Erin extension was announced in early 2023, bringing the new overall length of the tunnel to 16.2 kilometres. The cost of this extension will be added to the total cost of the project when it is made public.

Key Dates

Aug 2019 Construction Commencement
Dec 2026 Expected Construction Completion - Central Interceptor project
Dec 2028 Expected Construction Completion - Point Erin Extension

Funding contributions

User charges


Successful Tenderer: Ghella Abergeldie Joint Venture (GAJV) was appointed in early 2019 as the Main Contractor by Watercare
Related contracts:
Design support and detailed design
Successful Tenderer - Arup

Schematic design and detailed design
Successful Tenderer - Jacobs

Subconsultants to lead designer
Successful Tenderer - AECOM and McMillian Jacobs Associates


May 2018 RFP's opened for the Central Interceptor
Sep 2018 Tenders were submitted for the project by four short-listed contractors.
Nov 2018 AGJV were announced as the preferred bidder for the porject.
Mar 2019 Watercare and AGJV formally signed the contract to deliver the Central Interceptor
Aug 2019 Construction commenced on the Māngere Pump Station
Dec 2023 WaterCare announces cost increase of NZ$204 million, approved by the Board on November 7. This covers construction of the tunnel to Tawariki St, Grey Lynn (due for completion mid-2026) and includes provision of $109m to address the impacts of ongoing inflation to the end of the project. This is in addition to the former cost increase to NZ$1.31 billion due to project scope changes, bringing the new cost of the project to NZ$1.523 billion. This costing does not include the additional 1.5km Grey Lynn to Point Erin extension, with this part of the project undergoing further planning. No cost for this extension was announced.
May 2024 WaterCare announced that funding has been confirmed to extend the Central Interceptor wastewater tunnel by more than one kilometre from Grey Lynn to Point Erin, Herne Bay to reduce wet weather overflows and improve water quality in Herne Bay and St Marys Bay waterways and beaches. The funding was to be shared between Auckland Council and Healthy Waters, but Watercare did not confirm the quantum of funds committed. The Point Erin extension was expected to be commissioned in 2028 when it connects to an upgraded Herne Bay Trunk Sewer.
Estimated Total Cost
Water & Sewerage
Procurement approach
Traditional Procurement |
New Zealand |