Water use, sustainability, and efficiency by choosing quality systems and materials, and providing environmentally friendly solutions.


By minimising water use, and making good materials choices, you can reduce running costs, cut demand on community infrastructure, and reduce harm to the environment.

For water supply and drainage, the first consideration is building users’ health and safety. A system is not sustainable if it does not meet basic needs for drinkable water and for safe disposal of waste.

At the inquiry into the serious illness outbreak in Havelock North in 2016,  experts estimated that, on top of mass outbreaks, the number of people who fall ill from unclean water in New Zealand is between 18,000 and 100,000 each year.

On 21 November 2021, Taumata Arowai became the new independent water services regulator for Aotearoa New Zealand, taking over from the Ministry of Health.

In addition to meeting health and safety requirements, good design will ensure the efficient and sustainable use of water, energy and materials.

For water supply, there are many things to consider, ranging from the type of water heating used to the layout of pipework to specifying appliances and fixtures. These decisions can have a significant impact on water and energy use over the life of a building.

For wastewater treatment, the key decision is whether to connect to the mains sewerage network, treat wastewater on-site, or a combination of both. Either way, it is important that health and safety requirements are met.

Stormwater runoff places demand  on infrastructure and can carry contaminants into waterways such as streams and the sea.

All water and wastewater costs are borne by building owners and occupiers, through rates and user charges. By designing, building and renovating homes that use water efficiently, you can help keep these costs down.

Incorporating water saving devices in a house can also result in it achieving a much higher score in rating tools such as Homestar. This gives homeowners an independent measure of their home’s efficiency and sustainability – and can be a useful marketing tool if and when they choose to sell.

Reducing water use also benefits the environment by, for example, reducing the need to draw more water from rivers and waterways, reducing demand for energy, and reducing the need to build new infrastructure for supply and disposal.

The key plumbing standard is AS/NZS 3500 Plumbing and Drainage, which has four parts that cover water services, sanitary plumbing and drainage, stormwater drainage and heated water services.

The 2018 version of AS/NZS 3500 is the one currently in use as means of demonstrating compliance with the Building Code in building consent applications. Although 2021 versions of parts 1 to 4 of the standard were published in May 2021, using them in building consent applications would be as an alternative solution. The 2021 versions are expected to come into effect as a means of compliance in November 2022.

This section of the Level website incorporates material from the BRANZ publications Water and Plumbing.

BRANZ has more research-based guidance about water management in the online resource Up-Spec.


Updated: 29 November 2021


    Water supplyWater use, sustainability, and efficiency by choosing quality systems and materials, and providing environmentally friendly solutions.