Network environmental performance early insights 2024/25
What the most recent data is telling us about the current environmental performance of New Zealand’s public water networks.
Our Network Environmental Performance Report (NEPR) for 2024/25 will be released in mid-2026, providing a comprehensive view of the state of our drinking water and wastewater network, enabling comparisons between different networks and regions and providing trends over time.
Environmental performance data covers 560 public drinking water networks and over 320 public wastewater treatment plants.
Our data analysis is ongoing but, in the interim, we are sharing some early insights.
Network Environmental Performance Report Provisional Data Release 24/25outbound
Overall: How well are our public water networks performing
- A concerning picture is emerging of aging infrastructure, deferred or inadequate maintenance and poorly performing networks.
- While the data provided this year is better quality than in previous years, there are areas where we do not have full confidence in the assessments made by network operators on the condition of their assets.
- With the establishment of new water organisations from 1 July 2026, having robust information about networks will be fundamental for making decisions about where to prioritise investment in infrastructure renewals, upgrades and maintenance.
This year, for the first time, the NEPR will report on our wastewater network, including the volume, location and treatment level of wastewater discharges into the environment and the number and cause of overflows.
Wastewater network performance
New Zealand’s public wastewater infrastructure is particularly vulnerable
According to the data reported to us, much of New Zealand’s public wastewater infrastructure is in an unknown or poor condition. Over half of our wastewater treatment plants will require reconsenting in the next decade. A sizeable proportion of plants are operating on expired consents. Some plants have had lapsed consents for as long as 20 years.
Both the plant and underground network infrastructure are suffering from deferred maintenance. Pressures such as extreme weather events, population growth and urban development are also a challenge for aging infrastructure. Most councils are facing substantial upgrades of some form.
In recognition of this challenge, the Authority has been given a range of legislative powers from information gathering to standard setting, to help drive infrastructure improvements, enable public transparency and ensure accountability for wastewater network performance.
A key first initiative; national wastewater environmental performance standards, announced in late 2025, enables certainty for wastewater infrastructure performance expectations and will help to lift overall performance while also enabling cost efficiencies and enhanced transparency.
Wastewater standards
Most wastewater overflows were caused by flows exceeding the capacity of the network or by blockages
Overflows, when untreated wastewater spills to land, freshwater or out to sea, are a persistent problem for networks. More than a third of reported overflows were due to capacity of the network being exceeded, for instance where the pipes are unable to cope with rainfall or where urban growth has put a strain on the networks. A further third were caused by system blockages, which can be an indication of maintenance or operational issues.
Wastewater networks in poor condition can be more prone to inflow and infiltration of stormwater, which can overwhelm the network, contributing to overflows. Combined wastewater and stormwater pipes and degraded network infrastructure also increase the risk of overflows as the network capacity is more readily exceeded.
Overflows and bypasses are often confused
A very small number of bypasses were reported, indicating providers may lack understanding of the difference between bypasses and overflows.
Overflows occur where untreated wastewater escapes from a wastewater network into the environment. Bypasses occur where partially treated wastewater is diverted to protect a treatment plant.
Drinking water network performance
Some drinking water networks are operating under reference pressure
A focus of this year’s report will be about network water pressure as an indicator of public health risk. We have previously reported on the high proportion of water lost from networks by many of New Zealand’s public operators. One way to mitigate water loss from a network is to reduce pressure in the network. However, when pressure is reduced to levels that are too low, the risk of contaminants entering the drinking water network increases. It is concerning that some operators are operating networks below their reference pressure.
Further analysis will reveal whether the lower pressures correlate with reduced water loss.
This year, our report will cover the uptake of water metering. From the submitted data, early indications suggest under two thirds of residential connections have some form of water metering, with about 70% of non-residential connections having meters.
There has been a marked lift in the quality and timeliness of data provided by network operators
The Authority is encouraged by the marked improvement in the quality and timeliness of the 2024/25 data. While there are still areas needing further attention, operators are familiarising themselves with the reporting requirements and growing their understanding of their compliance obligations.
We are developing a deeper understanding of the environmental performance of our water networks and using this knowledge to guide improvements, manage risks to public health and the environment, and respond swiftly to the challenges posed by our changing weather patterns and aging infrastructure.
