Downstream supplies policy statement
The Water Services Authority – Taumata Arowai has published a downstream supplies policy statement to clarify when a downstream drinking water supply exists, and what responsibilities apply.
This work responds to feedback from the sector and is designed to remove uncertainty, support consistent decisions, and ensure risks to drinking water are managed appropriately.
Why this policy statement is needed
The Water Services Act 2021 anticipates downstream supplies but does not clearly define them. This has led to:
- uncertainty about whether a supply needs to be registered
- inconsistent decision-making
- unnecessary compliance costs in some cases
- potential public health risks where responsibilities are unclear.
The policy statement helps suppliers determine whether they are part of a downstream supply arrangement. It focuses on public health risk and is designed to support more consistent and proportionate regulatory decisions across the sector.
Downstream supplies
A downstream supply is where:
- a supplier receives drinking water from another (upstream) supply
- that supplier then supplies the water to others
- the supplies are owned by different suppliers
- additional treatment or management of specific risks is needed to ensure the water remains safe
The policy statement sets out key features to help suppliers self-identify whether they are a downstream supplier.
We recognise that this may not pick up every situation so suppliers should get in touch if they have any queries. Where needed, the Authority can also use its statutory powers to determine whether a supply is, or is not, a downstream drinking water supply.
How the Rules support this
The updated Drinking Water Quality Assurance Rules 2026 clarify which requirements apply to downstream supplies, along with supporting guidance and tools. These are intended to give suppliers greater certainty about their obligations.
Responsibilities
Downstream suppliers
Downstream suppliers are responsible for providing safe drinking water to their consumers.
They must either follow the Drinking Water Quality Assurance Rules and have a Drinking Water Safety Plan, or use an Acceptable Solution (where appropriate).
- Read the new Water Services (Drinking Water Quality Assurance) Rules 2026 (these will come into effect on 1 July 2027).
- Read Preparing a drinking water safety plan.
- Read about Acceptable Solutions.
Downstream suppliers:
- only need to follow rules relevant to their supply
- must meet treatment and distribution requirements where applicable
- do not need to meet source water requirements unless they have their own sources.
New or currently registered downstream suppliers need to comply with the new rules from 1 July 2027.
Existing downstream suppliers that were suppling water prior to 15 November 2021 but weren’t registered with the Ministry of Health have until 15 November 2028 to register with us, and until 2030 to be fully compliant with the Act.
Upstream suppliers
Upstream suppliers are responsible for providing safe drinking water up to the point of connection with the downstream supply.
They must:
- ensure water is safe before it leaves their supply
- notify downstream suppliers of any risks or non-compliance.