Greywater Treatment Systems
A greywater treatment system collects, stores, treats and may disinfect greywater to the standards specified by the various State government / local government authorities.
Greywater Treatment Systems can be installed in residential households in most sewered areas to provide treated greywater for use for irrigation (including surface irrigation), toilet flushing, washing machines and washing of vehicles, paving, and fences – please check with local / State authorities.
Treated greywater can also be stored for later use. Note that some councils or states DO NOT allow greywater treatment systems to be installed in sewered areas (e.g. Tasmania) – please check with your local council for regulations.
Source and application of treated greywater
For a greywater treatment system, the sources of greywater include:
- washing machines
- laundry tubs
- showers
- basins
- baths
- associated floor drains
Kitchen water is generally not recommended as the solid material, fats and oils can impact the treatment process. If used additional filtration may be required. Check with manufacturers of the greywater treatment system.
Greywater sources for greywater treatment systems. Kitchen use is not recommended in some states, but can be used with the addition of specific treatment systems. Source: Standards Australia and the National Water Commission
The degree of treatment is usually measured by a number of parameters which then determine what the greywater can be used for.
Some greywater treatment systems can also lower concentrations of nitrogen and phosphorus. This is relevant from an environmental perspective if these nutrients are not required for plant growth, or greywater is used for washing vehicles or fences, as this water may run off the site and cause environmental problems.
A greywater treatment system is small wastewater treatment plant and the installation and maintenance must comply with guidelines to ensure human health and the environment is protected. To ensure this the plumber and householder must take on the responsibilities associated with the correct installation and on-going management of the greywater treatment system.
Responsibilities for Greywater Treatment Systems
| Responsibility | Householder/owner | Plumbers |
| Undertake a water balance to determine water demand requirements | Yes | Yes |
| Ensure greywater treatment system meets the requirements of the local and state/territory | No | Yes |
| Ensure the greywater treatment system is WaterMarked | No | Yes |
| Apply for and obtain approval to install and operate the greywater treatment system and greywater irrigation system from the local council | No | Yes |
| Engage a licensed plumber to install the | greywater treatment systemYes | No |
| Install sub-soil, sub-surface or surface irrigation system to distribute greywater (the level of treatment will reflect possible irrigation systems | Yes | No |
| Notify the local water utility that a greywater treatment system has been installed at the property | No | Yes |
| Undertake regular maintenance of the greywater treatment system in accordance with the manufacturer’s recommendations and relevant guidelines | Yes | No |
| Ensure that annual testing of backflow protection device is undertaken | Yes | No |