OIA response CAS 01982 V4M6K1.pdf.pdf

OIA Ref: CAS-01982-V4M6K1

16 December 2025

Sovereign Sharna
[FYI request #32674 email]

Tēnā koe Sharna

Request for information relating to fluoride supply chains
On 26 November 2025, we received a partial transfer of an information request by you, from the
Ministry of Health under the Official Information Act 1982 (OIA):
“3. Provide the full chemical composition, including chemical names, chemical formulae, and
concentrations of all fluoride compounds added to the public water supply.
5. Provide details of any chemical by-products, waste, or residues generated during production,
storage, transport, or dosing, including their environmental and human health impacts.
15. Include all corporate affiliations, financial interests, and advisory bodies that influence decisions
regarding fluoride.
16. Provide copies of all risk assessments, environmental impact statements, monitoring reports, and
internal or external evaluations regarding fluoride safety, dosing, and public health.
17. Provide documentation of regulatory compliance, inspections, or audits by government or third-
party authorities.
18. Disclose any incidents, complaints, or breaches relating to fluoride chemical safety, handling, or
dosing.
20. Include international case law, peer-reviewed studies, legal decisions, or environmental
assessments showing health or environmental risks, chemical by-products, or public health outcomes
linked to fluoride.”
Our response to your request is set out below.
Response
1.  The Authority notes the Ministry of Health's response to you advised that your request has also
been transferred in part to numerous local authorities. We encourage you to contact these local
authorities for the information you are seeking.
Question 3: Fluoride compounds
2.  Our legislation does not prescribe which chemicals are used for drinking water fluoridation. This
factsheet, produced by Water NZ, provides information about drinking water fluoridation in New
Zealand including the chemicals used: WaterNZ | Good Practice Guide | Supply of Fluoride for
Use in Water Treatment
Question 5: Fluoride dosing and its impacts
3.  The Drinking Water Standards (Standards) provide the maximum acceptable value (MAV) for
substances in drinking water. The MAV for fluoride is 1.5mg/L, which is in line with the guideline

value set by the World Health Organization (WHO) and adopted in jurisdictions such as Australia
and the European Union. The MAV for fluoride in the Standards covers both naturally occurring
fluoride and fluoride added to drinking water.
4.  The WHO Guidelines for drinking water quality provide information on how the WHO sets the
guideline values: Water Sanitation and Health | World Health Organization.
5.  The WHO assessment information for fluoride is available here: Fluoride Background Document |
World Health Organization.
Production, storage and transport
6.  The production, storage and transport of water treatment chemicals is outside of the scope of
our legislation. Dosing is in scope to the extent that any fluoride added to water must be
maintained at a level below the MAV.
7.  The environmental and human health impacts of fluoride are more closely related to the
legislative functions of the Environmental Protection Authority (environmental impact) and the
Ministry of Health (human health). Information from the Environmental Protection Authority was
also provided in the response to your request from the Ministry of Health. You can find more
information about the roles the agencies have here:
•  Ministry of Health: Implementation of community water fluoridation | Ministry of Health NZ
•  Environmental Protection Authority: OIA-Response-2-August-2023-Fluoridation-of-water-in-
NZ.pdf.
Question 15: Interests and advisory bodies influencing decisions
8.  The only information held by the Authority in relation to this question is information from the
World Health Organization, which influenced decisions for setting the MAV. See questions 16 and
20 for further information.
Question 16: Risk assessments, impact statements and monitoring reports
9.  The only assessment the Authority holds for this question is the WHO fluoride assessment that is
available here: Fluoride Background Document | World Health Organization.
Question 17: Provide documentation of regulatory compliance or audits
10. We have considered this question in two parts: documentation for regulatory compliance, and
documentation for inspections or audits.
Regulatory compliance
11. The Drinking Water Quality Assurance Rules (Rules) require a supplier that adds fluoride (or other
chemicals) during the treatment process to monitor drinking water for these chemicals.
12. Where a supply serves over 500 people, the fluoride concentration in drinking water must be
continuously monitored. Supplies serving 101-500 people where fluoride is added are required to
monitor the concentration at least eight times per month.
13. If the concentration of fluoride (or any other chemical) exceeds the MAV set out in the Standards,
suppliers are required to:
a)  Notify the Authority;
b)  Take actions to protect public health;
c)  Investigate the cause; and
d)  Implement measures to prevent recurrence.
14. All water suppliers dosing fluoride are required to report to the Authority to demonstrate they
are meeting the requirements of the Rules.

Inspections or audits
15. Although all water suppliers are required to report to the Authority, these reports don’t
constitute an audit or compliance review. Based on this, this part of your request is refused
under section 18(g) of the OIA.
Question 18: Incidents, complaints, or breaches
16. We have considered this part of your request in two parts; incidents, complaints or breaches
relating to dosing, and incidents, complaints or breaches related to chemical safety and
handling.
Dosing
17. The only information the Authority holds for this question is related to the breach of MAV
exceedances, which can be as a result of dosing.
18. The Authority has reviewed our records and has identified one MAV exceedance notification for
a registered supplier since November 2021. The supplier's investigation found that this sample
was taken when the plant was not in production and was therefore not representative of the
drinking water being supplied. This was supported by sampling from another point in the supply.
19. Laboratories have reported four other exceedances of the MAV for supplies that are
unregistered/unknown to the Authority. Because these supplies are unknown to the Authority,
we cannot provide a lot of information to you on these exceedances; however, we do know that
three of the four had been through a treatment process after the point of supply. This means
the notifications were not representative of the drinking water that was supplied to the
communities.
Chemical safety and handling
20. In relation to fluoride ‘chemical safety and handling’, the Authority does not hold any
information as we do not receive complaints about these matters. We also do not believe this
information is held by any other agencies. Based on this, this part of your request is refused
under section 18(g) of the OIA.
Question 20: Assessments showing health or environmental risks
21. The only assessment the Authority holds for this question is the WHO fluoride assessment that is
available here: Fluoride Background Document | World Health Organisation.

Right to complain
You have the right by way of complaint to the Ombudsman under Section 28(3) of the OIA to seek an
investigation and review of this response. Information about how to make a complaint is available at
www.ombudsman.parliament.nz or freephone 0800 802 602.
Ngā mihi

Steve Taylor
Head of Operations