Significant wastewater plant upgrade confirmed for Palmerston North
Published on 30 September 2026
Palmerston North’s wastewater will soon be treated to a much higher standard, with the upgrade expected to cost significantly less than proposed in our current Long-Term Plan.
Elected members decided at a council meeting today on the way forward for Nature Calls, the city’s long-term wastewater treatment and discharge project.
The decision means our treatment plant will get a significant upgrade, which at this stage is expected to cost $340 million, to remove more nitrogen and phosphorus, achieve extremely low bacteria levels, and exceed new national standards for all other requirements before it’s discharged to the Manawatū River at or near the existing outlet on Tōtara Road. This represents a significant step change in the quality of treated water going into river.
Alongside the treatment plant upgrade, about $40 million over 40 years will be set aside for an adaptive management programme, allowing further improvements to be made over time. This could include investing in new technology to improve the treatment, diverting wastewater from the river at times, land irrigation, wastewater reuse, riparian planting, community offset funds, or other improvements.
Affordability has shaped the solution
The decision follows several years of reassessing Nature Calls after the cost of the previous proposal became unaffordable.
Nature Calls began in 2017 to identify a long term solution for wastewater treatment and discharge before the city’s existing discharge consent expires in 2028. Following several rounds of technical and cultural assessments and community consultation, Council selected a hybrid land and river discharge solution in 2021 and lodged a resource consent application with Horizons Regional Council in 2022.
By 2024, however, the estimated cost of carrying out that proposal had increased to more than $640 million. Feedback through the 2024–34 Long-Term Plan told us that was unaffordable for our community.
Elected members responded by setting a $480 million project cap, plus inflation, and asking staff to investigate what could be delivered within that budget.
Mayor Grant Smith says the revised budget and new national Wastewater Environmental Performance Standards (WEPS) narrowed the solutions available. Higher-cost alternatives, such as discharging wastewater to land or piping it out to the ocean, could not be delivered to the new standards within the revised budget and were ruled out.
“This will be a significant upgrade to our treatment plant, so what is entering the Manawatū River is treated to a much higher standard. It will be some of the highest treated wastewater in New Zealand. We’ll also have an adaptive management programme alongside it, giving us the flexibility to make further improvements as technology develops and new opportunities become available. It gives us a way forward that improves how we treat our wastewater while recognising what our community can afford.”
Mayor Smith thanks iwi for their feedback, along with businesses and the wider community throughout Nature Calls. The partnership with iwi will continue as the project moves into delivery under Central Districts Water, including working together to develop the framework for adaptive management, and how this is managed and delivered.
The decision follows public feedback on two river discharge options earlier in the year
Following the introduction of new national Wastewater Environmental Performance Standards late last year and further technical work, Council narrowed the available options to two river discharge approaches and received feedback from the community again in April. Both were designed to meet the new national wastewater standards and the revised project budget.
The alternative option also included a significant upgrade of the treatment plant but used two discharge locations – Tōtara Road during higher river flows and a new discharge below Ōpiki Bridge during lower flows. It needed a new pipeline and pumps, and was estimated at $370 million, plus $40 million for adaptive management. Feedback between the two options was generally split.
Adaptive management builds flexibility into the next 40 years
Adaptive management is an important part of the solution and will cost about $1 million a year over 40 years (including a 5-year construction period and 35-year resource consent totalling $40m).
Mayor Smith says rather than trying to lock every aspect of wastewater management into one solution now, it allows additional measures to be introduced over the life of the consent as technology improves, environmental expectations change or new opportunities emerge.
“Wastewater technology will continue to change over the next 35 years, so adaptive management means we don’t have to pretend that the solution we design today will be the only answer available to us for the next three decades. We can make the major treatment improvements we need now, while also being able to do more over time.”
Central Districts Water will take over the delivery of Nature Calls
Today’s decision gives the project a clear direction before Palmerston North’s water services transfer to Central Districts Water on 1 July 2027.
Central Districts Water is jointly owned and governed by Palmerston North City Council, Horowhenua District Council and Rangitīkei District Council and will be responsible for drinking water, wastewater and stormwater services across the three districts.
From 1 July, it will take over responsibility for Nature Calls, including funding and delivering the project. Until then, we remain responsible for progressing the work and meeting our legal and regulatory obligations.
Central Districts Water will ultimately determine how Nature Calls is funded. The new water organisation will have greater borrowing capacity than Council currently has, providing greater ability to continue to invest in Nature Calls alongside other key water infrastructure over time.
More information about Nature Calls is available at pncc.govt.nz/naturecalls