A new report has revealed New Zealand’s worst and best performing regions when it comes to water management.

This includes which councils were losing the most water through leaks – and the much-maligned Wellington Water barely scrapes into the top 10, with others losing far more – keeping in mind the date range excludes the failure of the Moa Point wastewater treatment plant.

Billed as the first national picture of public drinking and waste water network environmental performance, the report from the Water Services Authority – Taumata Arowai warns of “immense” and “severe” pressures across the country.

WSA head of systems, strategy and performance Sara McFall says with councils’ new Local Water Done Well organisations starting up and the Commerce Commission set to oversee pricing, New Zealand is now at an “inflection point” for water.

The report also provides data on council performance on key measures of water management, with a series of charts in the second appendix.

RNZ has reproduced charts showing the best- and worst-performing councils or regions in each category, along with explanations of what is being measured.

As well as the various councils and council-controlled organisations, the report also covers three government organisations (Ministry of Education as the manager of schools; Department of Conservation; and Corrections) as well as the Defence Force.

Note: Statistics for Auckland and Watercare are reported separately, and some councils did not submit data that met the WSA’s quality thresholds for measuring their performance. All measurements are for the 2024/25 financial year ending 30 June 2025. Note also that this means the Moa Pt failure in February 2026 is not covered.

Total usage per connection

This category measures how much water is provided across each council’s networks, per connection – which is often a household, but can also include farms, businesses and the like.

This measure of total usage includes water provided to homes through taps and toilets, combined with any losses through pipe leaks.

“It is effectively the water entering the distribution network after treatment and before end use,” a WSA spokesperson said.

Leaks by volume: Current annual real loss

This category is a measure of how much water is lost from the network through things like leakage, pipe bursts, reservoir overflows etc.

“CARL is usually not measured directly. It is typically calculated using information about water supplied to the network, customer consumption, and other information,” WSA said.

Residential usage

This category shows how much each connection used on average (excluding losses).

However, the Water Services Authority warns the data in this category are not entirely reliable – particularly considering it suggests every household in Westland uses nearly 4000 litres of water every day.

“Although reporting coverage increased substantially in 2024/25, without commenting on the specifics of this case, there are still concerns about the accuracy of some reported water consumption values – and in some places mixed rural and household use may be a factor,” WSA said.

“So, while the figure does indicate approximately 3929 litres per residential connection per day based on the data submitted (in Westland), it should be interpreted with some caution and may reflect local network characteristics or data limitations rather than actual household consumption alone.”

Wastewater overflows as a proportion of network size

This category shows how many overflow events are recorded per 100km of wastewater pipe in the network, and is the first time the Water Services Authority has reported on it.

Note that unlike the above categories, this is shown according to the number of overflows, rather than volumes of water.

Councils have been grouped together where they record the same number, so that both Palmerston North and Ōtorohanga count as the 10th-equal highest, and the six councils with three overflows per 100km count as the 10th-equal lowest number of overflows.

This gives totals of 11 and 13 councils respectively.

Drinking water – spending

This category shows how much is being spent on drinking and wastewater systems per person in the 2024/25 financial year.

Although the total biggest and smallest spenders are ranked using a total, the chart also includes a breakdown of capital spending (that is, new plants, pipes, machinery and the like) versus operating spending (employee pay, energy costs, other spending for just keeping things running).