The regulator’s report on drinking water regulation shows some major improvements in protection against infection, particularly in schools.

Water Services Authority Taumata Arowai’s Drinking Water Regulation Report shows from 2023 to 2025, large council supplies meeting or almost meeting requirements has increased from 49 to 77 percent.

The number of long-term drinking water advisories for schools was also down from 17 to seven in the same year, and schools were more consistent about notifying the authority.

Taumata Arowai head of operations Steve Taylor said the results real improvements in how suppliers were treating, monitoring and reporting.

“Treatment barriers, regular monitoring and prompt action when something goes wrong are practical safeguards. They help prevent people from becoming sick from their drinking water,” he said.

However, the agency said there was more progress still to be made, with at least one supply across 33 council areas missing a basic treatment barrier and 51 supplies missing protozoa barriers as of the end of 2025, affecting 311,000 people.

Protozoa barriers stop or kill single-celled bacteria and viruses from entering water supplies and can help prevent illnesses, such as the 2023 cryptosporidiosis outbreak in Queenstown that affected nearly 100 people.

Taylor said the regulator would use the report to focus its work, including working with suppliers.

He said the authority had issued four directions in 2025 to require suppliers to take action to protect drinking water.

About 84 percent of New Zealanders now rely on drinking water provided by suppliers registered with the authority.

The report showed 98 percent of council supplies had bacterial treatment barriers in 2025, up from 96 percent in 2023; 94 percent had residual disinfection barriers, up from 92 percent; and 90 percent had protozoal barriers, up from 76 percent.

About 415,000 more New Zealanders been receiving water from council supplies with a protozoa barrier.

The total number of supplies that reported contaminants above acceptable levels was down about 22.5 percent, and laboratory notifications were down about 25.5 percent.

Chemical monitoring also improved, from 54 percent to 81 percent of large treatment plants meeting or almost meeting requirements from 2023 to 2025.