Greywater planning & design for architects, builders & consultants

This section is intended for architects, builders and consultants seeking to include greywater reuse specifications or design guidelines in a project.

The following text provides a brief description of greywater requirements (mandatory or recommended) for inclusion in design guidelines. Pertinent notes regarding responsibilities are provided in italics:

Install greywater-ready plumbing

Install greywater-ready sanitary drainage plumbing as described in the Residential Greywater Ready Plumbing Guidelines (JBA, 2013) to allow for the future connection of a greywater reuse system as an alternative water source.

When installing the greywater-ready plumbing also consider the greywater reuse system location, power supply, greywater irrigation top-up water source and any routing of greywater irrigation to minimise site disturbance during installation.

Note: The term greywater-ready refers to the installation of separate sanitary plumbing that collects greywater from sources suitable for greywater reuse, separate from all the other wastewater sources.

Installation of greywater-ready plumbing does not require approval from the Local Government’s Environmental Health Officer (EHO).

Approved greywater reuse units

Only approved Greywater Diversion Devices (GDD’s) listed by the Department of Health (2016) are permitted to be installed.

Installation of greywater reuse units

Greywater Diversion Devices (GDD’s) must be connected to the sewer by a licensed plumber in accordance with the manufacturer’s specifications and the Department of Health (2010) Code of Practice for the Reuse of Greywater in Western Australia.

Note: Drip irrigation for greywater reuse does not need to be installed by a licensed plumber.
Approval to install a GDD is required from the Local Government’s Environmental Health Officer (EHO) prior to installation. Where a Greywater Treatment System (GTS) is to be installed, the unit will also require commissioning before final approval from the EHO is issued.

Landscape and irrigation

Greywater is to be dispersed via sub-surface/ strata irrigation below a minimum of 100mm of soil or mulch respectively. Drip irrigation specifically designed for greywater irrigation should be installed by an experienced greywater professional.

Note: More details on the regulatory requirements for installing greywater sub-surface/strata, including calculating irrigation areas, required setbacks, soil and site assessment criteria are available in the Department of Health (2010) “Code of Practice for the Reuse of Greywater in Western Australia”. Alternatively, a greywater professional can advise on system implementation to comply with these regulations.

About The Author


Greywater & Wastewater Industry Group. We are a group of water industry professionals who are active in the design, research, manufacture, installation and servicing of greywater and wastewater treatment systems. GWIG is a non-profit organisation which was formed in late 2010 in order to provide a united voice for a WA industry that is largely unsupported and under-acknowledged for the important work that it does.