Wastewater

With wastewater, the overriding consideration is building users’ health and safety.

Most buildings will connect to a town or city sewerage system. However, there are options for on-site disposal that can be used when there is no mains sewerage available. Some wastewater can also be recycled to reduce building water use.

In this section, we describe best practice options for installing standard wastewater systems. We also describe other options such as greywater recycling.

Code requirements

Installation of sanitary plumbing and drainage systems in New Zealand must be in accordance with NZ Building Code clause G13 Foul water or AS/NZS 3500 National plumbing and drainage.

The key objectives of Clause G13 are to safeguard people from:

  • illness due to infection or contamination as a result of personal hygiene activities
  • loss of amenity due to the presence of unpleasant odours or the accumulation of offensive matter resulting from sewage disposal.

To do this, sanitary plumbing and drainage must be designed to carry discharges away so that they:

  • do not cause nuisance or health risk
  • prevent foul air and gases that are generated in sewers, drains and plumbing systems from entering buildings
  • minimise the risk of blockage
  • minimise noise generated by the flow within the system
  • allow for access and cleaning
  • are durable

Acceptable Solution G13/AS1 applies to above-ground non-pressurised sanitary plumbing (i.e. pipes, fixtures and fittings above ground). Acceptable Solution G13/AS2[link] applies to drainage (i.e. below ground pipework).