Drinking water standards review
New Zealand’s Drinking Water Standards set quantity limits for the known
Over time, the body of international public health and scientific evidence grows, improving global understanding of the impacts of contaminants that may be present in drinking water. New Zealand’s Drinking Water Standards require regular review to keep up with advancing science.
The standards currently include maximum acceptable values (MAVs) for biological and chemical contaminants that may be found in drinking water. A selection of those MAVs will be considered in a scheduled review, due in 2027.
As well as public health factors, the review process will also consider any expected impacts of potential changes to the standards for New Zealand’s drinking water suppliers, regulators, laboratories, agencies and the New Zealand public, including cost implications.
This work will continue through into 2028 and any proposed changes will likely require public consultation.
How are the Standards reviewed?
The Authority, the Ministry of Health (MoH), Health New Zealand (HNZ) and the National Public Health Service (NZPHS), and the Ministry of Cities, Environment, Regions and Transport (MCERT) have agreed to review the standards on a five yearly cycle. The standards came into force in November 2022 and are due for review in 2027. Work on the review is already underway.
MoH, HNZ and NZPHS collectively provide public health advice, carry out the evidence review, identify and assesses current and emerging drinking-water contaminants, and advise on potential changes to the standards.
MCERT leads the regulatory process. Regulations to set the standards are made under the Water Services Act 2021 (the Act) by the Governor General, through the Executive Council.
How do we know what contaminants exist in New Zealand’s drinking water?
To understand what is in our water, water suppliers are required to take samples and have them tested for a range of contaminants and chemicals. Results of those tests are provided to the Authority.
Drinking water composition differs between source waters, which is why protection barriers and/or treatment of water is required to ensure water is safe to drink.
How are Maximum Acceptable Values (MAV) calculated?
MAVs are set to maintain water quality and keep consumers safe. They are based on public health science, international best evidence and the guidance of the World Health Organization (WHO).
New Zealand’s Drinking Water Standards are based on a tolerable risk aligned with WHO guidelines.
Where WHO guidance does not exist, or does not fit the New Zealand drinking water context, other international evidence is used to inform the standards.
MAVs are added, removed or changed as emerging evidence evolves.
New Zealand may set a MAV that differs from WHO guidance if doing so is considered more appropriate for New Zealand’s water conditions and to better protect New Zealand consumers.
When would any changes be implemented?
The review process needs to be robust and allow for public consultation, as well as consideration by Cabinet. If the Authority recommends additional MAV(s), or the removal of, or change to an existing MAV, it is likely that final decisions for this review would not be taken until 2028.