Water use, sustainability, and efficiency by choosing quality systems and materials, and providing environmentally friendly solutions.
By designing to minimise water use and making good materials choices, you can lower household running costs, cut demand on community infrastructure and reduce greenhouse gas emissions.
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.
In September 2021, the Minister for Local Government said that each year in New Zealand around 34,000 people become ill from their drinking water and many thousands of households in different regions must boil their water to drink it safely.
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:
- reducing the need to draw more water from rivers and other waterways
- reducing demand for energy used to collect and distribute water
- reducing the need to build new infrastructure for water supply and wastewater disposal
- reducing the carbon emissions that the water system accounts for, thus helping New Zealand move toward its 2050 net-zero carbon goal.
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. MBIE has proposed a 12-month transition period until November 2023, during which time both the existing and amended Acceptable Solutions and Verification Method will be treated as complying with the Building Code.
BRANZ has more research-based guidance about water management in the online resource Up-Spec.
Updated: 28 September 2022