Reservoir
Our future is sealed and secure
We’re dedicated to enhancing the wellbeing of the area, and that encompasses our people, roads, waterways and reserves. Our new reservoir forms part of this commitment, and we’ve already installed more than three kilometres of new drinking water pipes to meet our community’s current needs, and to allow for expected growth in eastern Porirua and Whitby.
The new reservoir will be more reliable in the event of a natural disaster, because it will be completely sealed and was designed using modern earthquake data and modelling for our area. It will hold nine million litres of stored, clean drinking water, increasing our total for the area to 13.5 million litres. This means eastern Porirua and Whitby residents will have continued access clean drinking water, even if there is a disruption to our water supply network.
Our construction partners at HEB will begin building the new reservoir in early 2026, and we’ll work together to ensure we’re protecting the environment around our build site. The project is expected to take about two years to complete.
Timeline
| Late 2027 | Construction of reservoir completed |
| Early 2026 | Construction on reservoir starts |
| Early 2026 | Finalise detailed design |
| Mid-late 2025 | Finalise preliminary design |
| Mid-2024 | Procure contractors to complete detailed design and construction |
| Early 2024 | Preliminary design issued for review by Wellington Water, Porirua City Council and Greater Wellington Regional Council. Resource consent and outline plan approved. |
| Late 2023 | Apply for resource consent from Greater Wellington Regional Council and share Outline Plan with Porirua City Council. |
| 2023 | Based off the investigations, the concept design is finalised and the preliminary design is progressed. |
| 2021-2022 | Vegetation clearance and significant ground investigation undertaken in the reserve at the end of Stemhead Lane. |
| 2021 | $136 million of the Housing Acceleration Fund allocated. A portion will help fund the reservoir. |
| 2019 | Following the creation of Te Rā Nui (previously known as Porirua Development), investigation into a potential reservoir site started. |
Want to know more?
If you’re looking for more information and can’t find it here, get in touch with our team.
For Stemhead Lane residents, or other close neighbours to the construction site, contact:
Russell Obee
Stakeholder Manager – HEB
027 394 4913
russell.obee@heb.co.nz
Reservoir frequently asked questions
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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.
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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.
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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.
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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.
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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.
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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.
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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.
