New Zealand's water regulator, Taumata Arowai, has released its third annual report on the country's water networks. It is the first to include full information on wastewater — the water that goes down drains and toilets — from all 71 network operators, covering 84 percent of the population. RNZ

The report covers 559 public drinking water networks with 687 treatment plants and 56,000km of piping. It also covers 331 public wastewater networks with 318 treatment plants and 35,000km of pipes.

About 15 percent of pipes were in poor or very poor condition. The report says the real number is probably higher.

The data showed 11,535 wastewater overflows in 2024/25. That is an average of 31 a day — meaning untreated or partially treated sewage spilled out of the system that often. Average water use across the country was about 678 litres per connection per day. About a third of councils had at least one drinking water network with "very high" leakage compared with international standards.

On the wastewater side, 22 percent of treatment plants were running on expired consents. A consent is the legal permission a plant needs to discharge treated wastewater into the environment. When it expires, the plant is operating without a current permit. Nearly half of all plants — 48 percent — were due for consent renewal within the next 10 years. On average, it took operators five and a half years to get a new consent.

About 74 percent of wastewater was released into coastal areas such as beaches and harbours. In cities, 99.6 percent of wastewater got the highest level of treatment, which includes filtering, removing nutrients and using ultraviolet light to kill bugs. But city networks had nearly three times as many blockages per 100 metres of pipe compared with smaller towns and rural areas.

Taumata Arowai was set up by the Labour government in 2020 after the Havelock North campylobacter outbreak, which made thousands of people sick from contaminated drinking water. Before that, water was regulated by the Ministry of Health. The National-led government kept Taumata Arowai when it came into office, though it scrapped the previous Three Waters plan for how water services should be run. Dr Sara McFall, who leads systems, strategy and performance at Taumata Arowai, is associated with the report.

The broader context here is that Taumata Arowai has been warning about pressure problems in pipes for some time. When water pressure drops too low, contaminated water can be drawn back into the drinking water supply from household or business connections. The regulator's earlier reports found very high pressure in some networks, which can cause more pipe bursts, especially in older areas.

Those pressure and leakage findings matter more when you put them next to the pipe-condition data in this report. If 15 percent of pipes are already in poor or very poor condition — and the report says that is probably a minimum — then the consent backlog makes things worse. Operators waiting five and a half years on average to renew consents are dealing with pipes that keep deteriorating. The 22 percent of plants already on expired consents are running in a regulatory grey zone in the meantime.

The city-versus-town divide is worth noting. Cities have excellent treatment at 99.6 percent, but also far more blockages. That is likely because cities have more people, older pipes and more connections in a smaller area. The report does not break down what causes blockages, but the age of the pipes and the pressure problems found in earlier reports fit with what the new data shows.

For people working in council water management, the report brings together what has been building across Taumata Arowai's publications over several years. The authority now has a national dataset covering most of the population. The political significance is that this data exists at all. The water reforms that created Taumata Arowai were controversial, and the National-led government kept the regulator while dropping the Three Waters delivery model — so the monitoring continues, just under a different structure.

What the report cannot do yet is show trends. Because it is only the third annual report and the first with full wastewater data, it is a starting point. Comparing year to year on pipe condition, overflows and consent compliance will become possible in future reports. For now, the numbers are a snapshot of a system under real pressure.