Western Water Supply programme
Supporting long term water security for Auckland
Duration
2015 – 2034
Location
Huia, Laingholm, Titirangi, Waima, Waiatarua
Status
Planning
Project overview
This programme of works is central to securing Auckland's water future. By upgrading ageing assets, building resilience and planning for long-term demand, we are ensuring the network can reliably supply water for decades to come.
The Western Water Supply Programme is a substantial body of work made up of several inter-related projects. The focus of the programme is renewing and upgrading critical infrastructure in our network, including the nearly 100-year-old Huia Water Treatment Plant, which has served generations of Aucklanders.
Protecting the Waitākere Ranges is central to how we plan and deliver this work. Our engagement with impacted communities, including residents and local businesses, will continue to be open, timely and focused on keeping communities informed.
What the programme includes
The Western Water Supply Programme will deliver several major infrastructure projects, including:
What is happening now?
Construction of the May Road Booster Pump Station in Mt Roskill began in April 2026 and remains on track for completion by mid-2027.
Groundworks for the Lower Nihotupu Pump Station are expected to start in 2027, with additional site investigations underway as design options are refined.
Preferred options have now been identified for the Upper Nihotupu and Huia Raw Watermain projects, which will progress through concept design, affordability assessments and further investigations as the designs continue to be refined.
We will continue working closely with residents and businesses to provide updates and support throughout the life of the programme.
Raw Watermains - Preferred options identified
Thank you to everyone who took the time to provide feedback on the proposed replacement of the Upper Nihotupu and Huia Raw Watermains.
Following environmental investigations, technical assessments, cultural input and community engagement, Watercare has identified preferred options for both raw watermain projects. These projects will now progress to the next stage of planning and concept design.
We understand there is no option that completely avoids all effects. Throughout the assessment process, opportunities to avoid and minimise environmental, community and construction effects were carefully considered alongside technical and cultural requirements.
Upper Nihotupu Raw Watermain
The preferred option is Option 3 – a tunnel from Seavers Camp to the replacement Huia Water Treatment Plant, with a short section between Seavers Camp and the Upper Nihotupu Dam replaced along a similar route to the existing watermain.
This option provides a reliable long-term solution while significantly reducing ecological disruption and exposure to natural hazards such as slips and rockfalls.
More information is available here: Replacement of the Upper Nihotupu Raw Watermain.
Huia Raw Watermain
The preferred option is Option 6, which involves conveying water from the Lower Nihotupu Dam via a new tunnel at the Parau disposal site to connect with the Upper Nihotupu tunnel at Jacobson's Depot.
This option improves resilience across the raw water network, makes greater use of existing infrastructure and significantly reduces impacts on roads, residents, businesses and recreational areas when compared with more disruptive surface construction options.
More information is available here: Upgrade or replace the Huia Raw Watermain.
How community feedback helped
Community feedback played an important role in assessing the shortlisted options.
Many people raised concerns about traffic impacts, road closures, access, construction disruption and protecting the natural environment. These themes were considered alongside technical, environmental and cultural assessments during the evaluation process.
The preferred options align closely with what we heard from the community, reducing surface construction impacts and minimising disruption wherever practicable.
Please see below for a map of the preferred options.
The shortlisted options
In late 2025 we shortlisted four options and hosted public information and drop-in sessions to present the options and hear from the community.
Community feedback, alongside findings from geotechnical investigations and other investigations, helped shape and refine preferred options to enable us to move into concept design.
To learn more about the shortlisted options, please watch the video below:
FAQs
FAQs
Why is the programme of works necessary and what benefits will it deliver?
Much of the western water network is close to a century old and nearing the end of its service life. The Western Water Supply Programme will renew critical infrastructure, improving water quality, reliability, and environmental performance.
Combines several projects into one ‘programme’ of works allows Watercare to coordinate detailed sequencing and planning to achieve system-wide resilience and efficiency, with a focus on minimising community and environmental impacts.
In terms of resilience, the programme of works will also strengthen Watercare’s ability to cope with drought and extreme weather events.
Were alternative options considered?
Yes. Multiple options for treatment plant locations and raw watermain alignments were considered through previous planning work, including the Huia Water Treatment Plant Replacement Project and subsequent reviews.
What consultation and process will be followed?
We will continue to engage with local communities throughout the design and delivery phases. Engagement will include:
- Ongoing meetings of the Huia Water Treatment Plant Replacement Project Community Liaison Group
- Regular briefings for the Waitākere Ranges Local Board and Ward Councillors
- Regular community newsletters via email and in letterboxes
- Public information sessions and “Coffee with Watercare” catchups
- Mana whenua hui and inter-agency coordination with Auckland Council and Auckland Transport.
What did we learn from previous engagement on the new Water Treatment Plant and Reservoirs?
Early site selection for the new Water Treatment Plant was subject to statutory consenting and appeal processes. Through this process, Watercare identified the need for clearer, more robust requirements to manage effects and provide assurance to community stakeholders. As a result:
- Consent conditions were strengthened through the Environment Court process
- Requirements now include more detailed ecological mitigation and monitoring
- Clearer limits and controls have been set for vegetation removal
- Construction management and reporting obligations have been enhanced, especially regarding traffic, noise, etc.
- Mana whenua involvement has been formally built into the process
A formal Community Liaison Group has been established to support ongoing community engagement and accountability.
How will we minimise its environmental impacts during these works?
All works will follow best practice environmental management to minimise impacts on the surrounding environment. Restoration planting and robust sediment control measures will be key components of the programme.
How will the upgrades help protect the environment and the Waitākere Ranges catchment?
The new infrastructure will reduce the risk of unplanned discharges, improve raw water handling, and support our wider commitment to protecting and restoring the Waitākere Ranges catchment.
How will the project accommodate population growth?
The programme has been designed with future demand in mind. The upgraded assets will support Auckland’s growing population. The North Harbour 2 watermain project will service the western and northern growth corridors, providing drinking water to an additional 200,000 to 300,000 people.
What is the estimated value of the programme of works?
The combined investment across the Western Water Supply Programme will be over $1 billion, delivered progressively over the next decade.
How long is the programme of works expected to last?
The programme is currently in the planning and design phases. Construction in the Waitākere Ranges will take place in stages between 2027 and 2034, dependent on consenting, procurement, and site sequencing. Construction on the new May Road Booster Pump Station in Mt Roskill is starting in April 2026.
Each project will have its own construction timeframe and community communication plan.