New central city reservoirs

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.  

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.

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.  

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.

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.

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.

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