Plumbing and drainage — a long-term strategy


The Ministry of Business Innovation and Employment (MBIE) is proposing changes to New Zealand Building Code compliance pathways for water supplies, foul water and surface water that support plumbing and drainage work in New Zealand.

Feedback on a number of plumbing and drainage proposals has been sought by MBIE. The proposals are:

• Lead in plumbing products

• Water temperatures

• Protection of potable water

• AS/NZS 3500 Plumbing and drainage standards

• Water supply system components

• Plumbing and drainage system material standards

• Resolving conflicts and editorial changes

Continuous improvement

These proposals are the latest in a series of continuous improvements to ensure Building Code compliance pathways for the plumbing sector are fit for purpose and up to date to help New Zealanders have safe and reliable plumbing systems.

This update will help support the provision of plumbing and drainage services that comply with the Building Code, and meet the safety and wellbeing objectives in the Building Act 2004.

The 2022 Plumbing and Drainage update is focused on improving the means of complying with the following three Building Code clauses:

• E1 Surface Water — Disposal of rainwater, and confirmation surface water cannot enter the building.

• G12 Water Supplies — Requires the safe supply, storage, reticulation and delivery of hot and cold water.

• G13 Foul Water — Requires the safe disposal of foul water to prevent illness and the loss of amenity due to odour and accumulated matter.

The update supports MBIE’s commitment to the ongoing development of technical Building Code solutions within the plumbing technical focus area, and is a key step towards:

• modernising compliance pathways for the plumbing sector to incorporate technical innovation and research which support current hydraulic theory and installation practices,

• promoting consistent outputs by improving alignment between Building Code compliance pathways for the plumbing sector, and

• addressing targeted technical issues and gaps within existing compliance pathways.

At the same time, other government legislative programmes are informing the work required in the plumbing and drainage space. These include:

• The New Zealand Government’s response to climate change and the Climate Change Response (Zero Carbon) Amendment Act 2019 which drives MBIE climate change policy towards low greenhouse gas emissions and climate resilience in New Zealand.

• The Three Waters Reform Programme, including the introduction of the Water Services Act 2021 which will help ensure all New Zealanders have safe, reliable drinking water, wastewater and stormwater services.

• Building Products Information Law changes which will ensure that basic information about building products and how to use them is available to users in New Zealand.


One of the challenges is that plumbing and drainage requirements in the Building Code are fragmented between various Building Code clauses, Acceptable Solutions and verification methods.

This makes it challenging to ensure designs and installations comply with all relevant aspects of the Building Code.

There are opportunities to improve consistency, clarity and certainty in these requirements, and create a more user-centric approach to address the issues.

Along with that, MBIE has recognised the importance of the standards cited for plumbing and drainage systems, and has looked to adopt the most recent version of these standards.

Building Code compliance relies heavily on cited standards for the compliance of pipe materials and plumbing and drainage system installations.

This is reflected in the priorities and focus of past updates which have focused on maintaining current citation of a number of standards.

Final decisions on the changes will be made and communicated later this year.

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