Stemhead Lane Reservoir
Our new water supply tank will make sure we all have access to drinking water. It will help our community grow, and be safe if we have a natural disaster.
Our future is sealed and secure
Work has started on our new reservoir (water supply tank) in Stemhead Lane, Whitby.
When it’s finished, our new water reservoir will mean we can hold 13.5 million litres of clean drinking water here.
Our construction partners at HEB are building the new tank, which will be 41 metres wide and hold nine million litres of water. It’s being built next to our existing 4.5 million-litre tank, and will take about two years.
We’re doing this work so everyone who lives here can access clean drinking water, whenever they need it. The project will make our water supply in eastern Porirua and Whitby safer, because the tank will be completely sealed. It was also designed using modern earthquake data and modelling for our area.
As well as keeping us safe, it’ll also prepare our community for growth. Already in eastern Porirua, we’ve installed more than three kilometres of new drinking water pipes.
When it’s finished, our new water reservoir will mean we can hold 13.5 million litres of clean drinking water here.
Our project timeline
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2019
Reservoir site investigations begin
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2021
Funding allocated
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2021 – 2022
Vegetation clearance and ground investigations
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2023
Concept design finalised
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Late 2023
Resource consent application lodged; outline plan shared with council
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Early 2024
Resource consent and outline plan approved
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Mid 2024
Contractors procured to complete detailed design and construction
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Mid-late 2025
Prelim design finalised
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Early 2026
Detailed designs finalised. Construction begins
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Late 2027
Construction completed
Timelines may need to be updated as we confirm plans and make progress. If something changes, we’ll let you know as soon as we can.
Want to know more?
If you’re looking for more information and can’t find it here, contact us.
If you live in Stemhead Lane or close to the construction site, please contact:
Russell Obee
Stakeholder Manager – HEB
027 394 4913
russell.obee@heb.co.nz
For general enquiries, get in touch with our team here.
Frequently Asked Questions
Why do we need a second reservoir?
We’re building a new, larger water supply tank (reservoir) to ensure both current and future residents of eastern Porirua have access to drinking water every day, including during a natural disaster. It will increase the amount of water available and stored from 4.5 million litres to 13.5 million litres, ensuring Whitby and eastern Porirua residents have continued access to clean drinking water, including during a natural disaster or other disruption to the water supply network.
Who will benefit from this new reservoir?
The new reservoir will benefit all residents in the area – while it will help supply emergency water to both eastern Porirua and Whitby residents, it will also take pressure off Porirua’s wider water supply network.
How long will it take to construct a reservoir?
Construction is expected to take about two years and is scheduled to start in early 2026. This will involve building the reservoir foundations and structure, along with a small building to house electrical and control equipment. Once the reservoir work has been completed, we will replant and landscape the area, as well as install a new stormwater management system around the reservoirs to ensure any rainfall after construction is filtered before it runs downstream.
How big is the reservoir?
The reservoir is around 41 metres in diameter (internal). It will help to store and supply an additional nine million litres of water, significantly increasing the amount of water available to residents during a water supply disruption.
What will the reservoir be made of?
The reservoir will be made of concrete and will be completely sealed. It has also been designed using modern earthquake data and modelling for the area, meaning it will be more resilient and reliable in the event of a natural disaster.
Who will build the reservoir?
Award-winning infrastructure and civil construction experts HEB are delivering the new reservoir on behalf of Te Rā Nui. HEB has significant experience and a proven track record of delivering successful infrastructure projects across Aotearoa New Zealand.
How will you protect the local environment?
During construction, two key stormwater management techniques will be used to help filter and clean water before it runs downstream:
On-site retention pond
We’ll install a temporary water retention pond with steep slopes, which allows run-off to flow into the pond. Sediment in the run-off will sink to the bottom of the pond, allowing cleaner water to flow out through a series of pipes.
Grass swale
Our contractors will create a shallow, broad grass channel, known as a grass swale. These direct and slow stormwater across grass or similar ground cover and through the soil. This allows for any run-off to be filtered before flowing downstream.
When construction is completed, we will also install a new stormwater management system around the reservoirs, which will support good stormwater maintenance and ensure we continue to protect our taiao (environment). Some plants need to be removed to build the new reservoir, but significantly more native species will be planted in the area upon completion. These combined measures will help to protect and enhance the surrounding environment for current and future generations.