Ruakiwi Reservoir Project | Securing Hamilton’s Water Future

Project update

The reservoir site on Lake Domain Reserve has been designated under the Resource Management Act for two new reservoirs.
Council also approved the reclassification of the land for two new reservoirs under the Reserves Act at its Community Committee meeting on 21 April.
From 1 July 2026 IAWAI – Flowing Waters will deliver this project.
The project will go to market to procure a construction partner with the contract expected to be awarded in August 2026.
Construction is planned to begin from September 2026 and is expected to take just over two years.

To increase the supply of drinking water and capacity for firefighting for our growing central city, we need to build two 25 million litre (ML) reservoirs. One by 2028 and the other from 2040.

Following significant technical, environmental and cultural investigation, the Ruakiwi site at Hamilton Lake (next to the existing Ruakiwi Reservoir) has been identified as the best site for the two new reservoirs and a valve chamber building.

The site has hydraulic advantages as it enables the best and efficient (by gravity) water supply to the city and has supplied the central city with water for over 100 years.

The new reservoirs will ensure a reliable, high-quality water supply for residents, businesses, and the Waikato Hospital. Increasing the water supply will support central city growth (by 2035 we're expecting 10,800 more people living in this area).

Stage 1: First reservoir – built by 2028

25ML reservoir - approximately the volume of eight Olympic sized pools.
Council has been allocated $150.6 million in Crown funding from the Infrastructure Acceleration Fund (IAF) for a range of infrastructure projects to enable more homes. The first reservoir is funded through the IAF programme.
60m diameter - approximately 10m longer than an Olympic sized swimming pool.
10m tall, 6m above ground.
The new reservoir will be the tenth in Hamilton Kirikiriroa.

Stage 2: Second reservoir – to be built from 2040

Hamilton will need multiple reservoirs over the coming decades. As part of Council’s early water modelling and growth projections, another reservoir of the same size of stage 1 will be needed to ensure the city keeps ahead of its demand for water supply.

Funding for the second reservoir will be considered in future long-term planning.

The benefits

Clean water and reliable water supply is essential for thriving communities and businesses.

Reliable and resilient water supply to keep your water of the highest quality.

Ability to attract new businesses and support residential growth.

Essential water supply to help our city grow well.

Enables more people to call the central city home.

Ensures plenty of water supply for firefighting purposes.

Construction of the first reservoir also includes features designed to enhance public use of this part of the Lake Domain Reserve, including a public viewing path around the reservoir, a new path connecting the reservoir to the lake with interactive features for visitors, and landscaping and native planting throughout the reserve.

More about the funding

Council has been allocated $150.6 million in Crown funding from the Infrastructure Acceleration Fund (IAF) for a range of water infrastructure projects.

Stage 1 reservoir is funded by the IAF.

You can find out more about IAF funded projects here

Timeline

Stage 1 - Completed

2025
Community feedback sought to help shape the final site design.
Stage 2 - Completed

2025
Applications to designate and reclassify the land to enable the construction of the reservoirs.
Stage 3 - Planning

2026
Construction begins on first reservoir.
Stage 4 - Planning

2028
First reservoir completed.
Stage 5 - Planning

2040
Second reservoir to be built from 2040. Funding will be considered in future long-term planning.

Community engagememt

As well as the formal consultation completed through the designation and reserve reclassification processes, Council carried out three rounds of public and local resident engagement during development of the project. Overall, feedback showed strong support for the reservoir design and associated features, including the public viewing path.

Learn more about the engagement completed for this project, including the community insights reports.

FAQs

What will happen to the current Ruakiwi Reservoir

The current Ruakiwi reservoir is considered a heritage site due to its aesthetic and engineering characteristics that were modern for its time.

The new central city reservoirs will be situated next to the current Ruakiwi reservoir. When the new reservoir is complete, the current one will be decommissioned to realise energy savings.

Although the current reservoir has done an excellent job for central Hamilton, it is starting to wear and does not provide the capacity needed for our growing city.

What’s the history of reservoirs at this site?

The current Ruakiwi reservoir is the third at the site, built in 1930s.  

First reservoir 1907

Second reservoir 1921

Ruakiwi reservoir 1932

The existing Ruakiwi reservoir - diameter of 25.6m and inside depth of 18.6m with a capacity of 9.5ML litres.

What’s so great about this location for reservoirs?

Moving water through pipes requires energy and pressure – from the river to the reservoir and reservoir to the tap.

Being on top of the hill is central to the supply zone, with multiple benefits including:

The location has sufficient elevation to service most of the central city through gravity.
Gravity doesn’t suffer a power cut or breakdowns so will always be available to get water to the community.
It’s close to the existing infrastructure for moving large amounts of high-quality drinking water around the city.

Does the project require any tree removal?

To accommodate the first reservoir, the removal of 59 trees is proposed. This includes:

12 native trees – 9 will be transplanted within the Hamilton Lake Domain, 1 is in poor health, and 2 are Pittosporum trees that are too large to transplant.
47 exotic trees – all of which will be removed. 18 of these are in below-average or poor health. One tree, a Cupressus lusitanica, is protected under the Hamilton District Plan. It is too large to transplant and will require resource consent to be removed.

When the second reservoir is constructed in 2040, a further 13 trees are proposed to be removed.

We are proposing to plant 144 replacement trees. Of these, 35 large trees are proposed to be planted onsite:

8 trees will be 4.5-6m tall when planted.
27 trees will be 2-4.5m tall when planted.

A further 109 trees, ranging from 1.5m to 4.5m in height, will be planted throughout the wider Hamilton Lake Domain and surrounding reserves network.

We’re also proposing 500m2 of gardens with approximately 2500 shrubs. Some gardens will be used for stormwater treatment.

Could the reservoirs go underground?

In the design we’ve shared the reservoir is set approximately 6 meters into the hill. That leaves around 4 meters of the reservoir above the top of the hill. If we dig further down, it impacts the hydraulic effectiveness of the location, meaning less work done by gravity and more pumping required to distribute the water to households and businesses.

Do the reservoirs affect the outdoor stage?

This project will not affect the stage at Lake Domain. The stage is down near lake level, the reservoirs are planned up the top of the hill next to Ruakiwi Road.

What is the cost of the reservoir?

The first reservoir is fully funded by the Government through the Infrastructure Acceleration Fund. The cost of installing the first reservoir is around $82million.