Treatment of our wastewater

Rotorua’s current plant has to date been the most successful initiative in reducing nitrogen going into Lake Rotorua. Our treatment plant is among the best in the country, treating wastewater to a very high standard. But it is in need for an upgrade to meet higher projected demand and to continue to reduce and maintain nutrient levels below the targets agreed under the Lakes Water Quality programme.

The plant receives about 20 million litres of wastewater daily and has a current capacity of 27 million litres.

Most wastewater going through the plant for treatment is from domestic use, with a small percentage from industrial use.

Our wastewater includes rain water, sediment, sewage, industrial wastewater and stormwater.

The treatment plant is sited on the eastern edge of Lake Rotorua in the Sanatorium Reserve - a reserve gifted by Ngāti Whakaue for public purposes under the 1880 Fenton Agreement. The plant uses a combination of a 5-stage Bardenpho process and Membrane Bioreactor, the first full biological nitrogen and phosphorus process used for municipal wastewater in New Zealand.

To protect the quality of the water in Lake Rotorua, the treated effluent from the plant is currently irrigated to pass through CNI land in Whakarewarewa Forest before the groundwater discharges to Lake Rotorua.

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