New Zealand report flags strain in wastewater networks

New Zealand's Water Services Authority has published a national report on the environmental performance of public drinking water and wastewater networks. It is the first edition to include a complete national set of wastewater data.

The Network Environmental Performance Report 2024/25 paints a broad picture of strain across water infrastructure, with wastewater overflows, drinking water leakage and consent compliance identified as major problems.

The findings come as the water sector undergoes structural change, with new water organisations being established and financing and operating models under review. The report is intended to provide an independent view of how the system is performing and where risks are emerging.

Wastewater networks stood out as the most acute area of concern. Operators reported 11,535 wastewater overflows during the year, or about 31 a day.

These overflows discharge untreated wastewater to land or water, affecting public health, recreation, food gathering and the wider environment. The report links the problem to capacity limits, heavy rainfall, poor asset condition and blockages.

Dr Sara McFall, Head of Systems, Strategy and Performance at the Water Services Authority, said the report should help guide decisions on where action is most needed.

"As new water organisations are established, improved financing tools and greater standardisation create opportunities to strengthen network performance over time.

"The Authority has an oversight role, providing an independent view of how the system is performing, where risks are emerging and where action is needed. This enables the public to see how their water services are performing and track improvements over time.

"The report shows that many networks are under immense pressure, and better data, maintenance and targeted investment are needed to reduce risks to public health and the environment and increase long-term system resilience.

"Good information is critical. Better monitoring, inspection and data quality practices will help operators make smarter decisions and achieve better outcomes for communities," McFall said.

Wastewater strain

Blockages remain a major and avoidable cause of wastewater overflows. Many are caused by fats, oils, wet wipes and other unsuitable materials entering wastewater systems.

That points to both an operational challenge for network owners and a public behaviour issue. The report recommends that operators focus on routine and preventative maintenance and direct spending to the parts of the network under the greatest pressure.

Consent compliance is another pressure point. The report says close to half of existing wastewater consents will need to be renewed within the next decade, adding to the workload for operators and regulators alike.

McFall said compliance remains weak in parts of the system.

"Capacity constraints, periods of torrential rain, poor asset condition and blockages are severely impacting the effectiveness of wastewater networks in many parts of the country," McFall said.

On blockages and maintenance, she added: "Blockages remain a major and preventable cause of wastewater overflows. These are caused by fats, oils, wet wipes and other unsuitable items entering wastewater systems, and New Zealanders need to understand they play a critical role in preventing blockages.

"We recommend that operators prioritise routine and preventative maintenance to reduce wastewater overflow risks before problems occur and target investment to the areas of greatest need."

The Authority also pointed to a regulatory response already under way. New national wastewater environmental performance standards published in late 2025 are intended to create a more consistent framework for councils renewing wastewater consents and to improve monitoring and public reporting of discharges and overflows.

Leakage issues

On the drinking water side, the report found uneven performance across the country. Loss of treated water remains a significant issue, with about one-third of councils reporting at least one network with very high leakage levels by international standards.

The report also says freshwater sources used for drinking water are under pressure in places where consumption is high or consent limits are exceeded. That raises questions not only about network condition, but also about how demand is managed.

Metering appears to be one factor separating stronger and weaker outcomes. Areas where most homes have water meters tend to use less water than the national average, suggesting metering can help reduce both water use and losses.

Use of meters remains inconsistent nationwide. New Zealand has about 980,000 residential water meters, and 19 councils and Crown-owned operators have meters installed at at least 90% of homes.

For operators, the practical priorities are to reduce leakage, improve their understanding of network performance, use metering and pressure management where appropriate, and plan for future water availability, network renewal and rising demand.

The Authority is also working on broader measures, including national engineering design standards for water infrastructure, simpler consenting pathways for smaller wastewater treatment plants and benchmarking information to support the use of water meters.

On wastewater consent conditions, McFall said: "We are aware of considerable non-compliance with wastewater consent conditions, but expect improvements through the new national wastewater environmental performance standards, which we published in late 2025, providing a clear and consistent framework for councils renewing wastewater consents.

"The new national standards also require consistent monitoring and public reporting for discharges and overflows, improving visibility and the ability to effectively enforce non-compliance."