St Marys Bay separation project

A water quality improvement programme to reduce overflows and clean up local waterways.
Start–finish: 2020-2024
Location: St Marys Bay
Status: Planning
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What's happening?

We've been working with Auckland Council on an initiative called the Western Isthmus Water Quality Improvement Programme which will help reduce overflows and clean up local waterways including the Waitematā Harbour.
Soon we'll begin investigations for an important phase of the works - to separate wastewater and stormwater in the local network and private properties across the St Marys Bay catchment (map below). The project will reduce diluted wastewater overflows, helping to improve the water quality of St Marys Bay and the harbour. The work will be jointly funded by us and Auckland Council, with no direct cost to home owners.

St marys bay separation project catchment map

What's involved?

The project will include the construction of a new wastewater pipeline and extension to the existing network. The existing network can then be used for stormwater. Some properties in the catchment will require individual separation and we will work with property owners to understand the extent of the work required. Click here for more information.

For work on private property, it will be undertaken under the Local Government Act and will ensure buildings are compliant with legislation. Every house needs to be separated to ensure wastewater does not flow through the stormwater pipeline and directly into the harbour via the new separate network. We will be contacting landowners directly if their property requires private network separation. We will also work with property owners to understand the works and whether any building consents are required. This process will ensure work on private property meets New Zealand building code requirements.

Timing of the works

st marys bay separation project timing of the works

Any Questions?

St Marys Bay separation project FAQs (September 2020)
If you have further questions, please email:


St Marys Bay separation project - newsletter June 2020

Related projects

Hackett Street, St Marys Bay
St Marys outfall project
Central Interceptor