Central Interceptor

Among other benefits this wastewater tunnel will reduce overflows by up to 80 per cent.

Start–finish: 2019–2025
Location: Western Springs to Mangere
Status: Detailed design

Diagram showing the project timeline

What’s happening?

The Central Interceptor is a wastewater tunnel that will run between Western Springs and the Mangere Wastewater Treatment Plant

The tunnel will run underground for 13 kilometres and will be at a depth of between 22 and 110 metres, as shown below. 
It will cross Manukau Harbour at about 15 metres below the seabed. Along the route it will connect to the existing wastewater network, which will divert flows and overflows into the tunnel.  
A diagram showing the proposed pipeline route

What are the benefits?

The Central Interceptor will:

Provide for future growth of Auckland 
The Central Interceptor is needed to ensure there is sufficient capacity in the network to meet planned population growth and development in Auckland. Without this, more overflows into the waterways and harbours will occur.

Reduce overflows to the Waitemata and Manukau Harbours 
During wet weather, the overall wastewater network currently overflows to the Waitemata Harbour at more than 200 points and to the north-eastern part of the Manukau Harbour at 14 points. The Central Interceptor is expected to reduce the annual average overflow volume by 80 per cent.

Reduce environmental risk for the Manukau Harbour 
The lower section of the Hillsborough Tunnel and Manukau Siphon is estimated to have a residual life of between 15 and 25 more years. If it fails, it could mean continuous untreated wastewater discharge into the Manukau Harbour for an unknown period of time from more than 200,000 customers, including industrial flows presently treated at the Mangere Wastewater Treatment Plant.

Watch a video explaining the project:


Any questions?

Please contact:
Email: CIProject@water.co.nz

More information

Media release (March 2018)
Fact sheet 
Hearing panel’s decision
Media release
Resource consent application
Project works evidence
Contractors' information

Minutes of the Meola Creek Community Liaison Group meeting

Minutes for meeting 8 August 2017
Minutes for meeting 10 May 2017​ 
Minutes for meeting 14 December 2016
Minutes for meeting 4 July 2016

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