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Our treatment plants
Te Pūnaha Maimoatanga Wai o Ōākura

Ōākura Water Treatment Plant

Source of water

Groundwater: Bore water from confined aquifer

Present capacity

2,740,000 L/day (normal current flow 865,000 L/day; peak 1,370,000 L/day)

Treatment

  • Bore water.
  • Ultra-violet disinfection.
  • Chlorination to provide residual disinfection in reticulation system.
  • pH adjustment to minimise corrosivity.

The water treatment process

The groundwater is pumped from two 180m deep bores drawing from a deep volcanic avalanche flow strata originating from the Pouakai Range. At the water treatment plant, the water passes through an ultra-violet sterilisation unit which acts as an added barrier against protozoa contamination.

Sodium hypochlorite and hydrated lime are added to the water leaving the Ultra-violet units. Sodium hypochlorite is added as a disinfectant to deactivate any micro-organisms that might be present in the water that is distributed to the reservoirs, and as a safeguard against further contamination of the reticulation system.

Lime is added to raise the pH of the water to 7.6, making the acidity/alkalinity level healthy for consumers and non-corrosive to reticulation and household plumbing. 

The water passes to two 1.2 million litre capacity reservoirs.

Page last updated: 11:26am Thu 27 August 2026

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06 759 6060 enquiries@npdc.govt.nz
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84 Liardet Street
New Plymouth

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