Choosing a greywater system
Water for the Future – Fact sheet
Department of the Environment, Water, Heritage and the Arts, 2009
PDF file
As part of its $12.9 billion Water for the Future plan, the government is delivering the $250 million National Rainwater and Greywater Initiative to help people use water wisely in their everyday lives. The following information may assist you to choose the right greywater system for your location and your needs.
What is a greywater system?
Greywater can be treated and re-used from a range of sources including the laundry
Source M. McAulay & DEWHA
A greywater system is a common term used to identify the collection and re-use of domestic wastewater from a range of sources that include your bath, bathroom basin, laundry or shower.
A greywater system can complement and increase your water savings or it can be an alternative to a rainwater system where your location, use and housing configuration may not make a rainwater tank suitable.
Greywater is classified into two categories 1) treated or 2) untreated. Greywater can be permanently or temporarily diverted for use.
- Temporary Diversion – For example, plastic pipes connected from the laundry to the garden.
- Permanent Diversion – Plumbed directly into the plumbing or drainage system of the home and divert water to the garden.
- Permanent Greywater Treatment and Reuse Systems – Plumbed directly into the plumbing or drainage system and include primary treatment, secondary treatment and disinfection systems. Some use aerobic disinfection, mechanical disinfection, membrane filtration or UV disinfection.
To claim the rebate under the National Rainwater and Greywater Initiative guidelines, households must install a permanent greywater treatment and reuse system.
Applicants in arid locations, homes with limited space or small roof catchments could consider a greywater system.
How do I select the right greywater system for me?
This will depend on a number of factors such as:
- household space and configuration;
- local and state health and planning regulations;
- end use and level of treatment;
- size of system and the number of people in a household; and
- budget and cost.
Factors to consider before installing a greywater treatment system
Space
Do you have enough space to accommodate the system? Is your garden and lawn large enough to take expected outflow?
Health regulations
The collection, storage and use of greywater if untreated and managed incorrectly can be hazardous to humans and plants. Greywater can contain harmful bacteria, pathogens and chemicals. Before purchasing and installing a greywater system, it is recommended that people contact their state health authority to establish the level to which their greywater must be treated, prior to re-use. All states require secondary treatment with disinfection in order to re-use greywater indoors.
Planning regulations
State governments and local councils have different regulations regarding the use and installation of greywater. In some states and local council areas the use of greywater is not recommended. Check with your local council regarding the use and installation of greywater devices prior to purchasing a greywater system.
End Use
The end use for re-used recycled water will depend on the quality of treatment. The higher the level of treatment the more possible re-uses you will have. A lower grade of treatment will result in water suitable for toilets and sub-surface irrigation of gardens and lawns. A higher grade of treatment will result in water suitable for direct application to certain plants, laundry, washing vehicles and in exceptional cases drinking.
Size of systems and number of people in a household
The number of people in your household and number of connections to different greywater sources will affect the ability of your greywater system to function correctly. The more connections to greywater sources you have and the higher the number of household occupants, the more likely it is that you will need a larger system with more features to cope with increased demand and storage during peak periods.
Cost
The cost of a greywater system can vary considerably between suppliers and manufacturers. Considerations are:
- Size of systems – will the system handle the number of occupants and greywater sources during peak loading?
- Type of treatment – will the systems treat all or only a couple of the following greywater contaminants: bacteria, pathogens, oils and greases, chemicals and nutrients?
- Grade of treatment – will the system deliver a grade of water that is considered acceptable for different uses by your local state health authority and local council?
- Installation – will the plumber be able to access all plumbing and pipes? Elevated homes generally provide easier access to greywater sources than homes on slabs.
- Maintenance cost – will your system be easy and cost effectiveto maintain? Does it require special bacteria, lighting and ongoing maintenance and use?
Greywater treatment systems with re-use
Greywater treatment systems usually include primary treatment in the form of a grease trap and coarse filter, some form of secondary aerobic treatment and disinfection. Some systems are quite advanced and use membrane disinfection followed by UV disinfection post treatment.
The cost of a greywater treatment system with disinfection that would allow re-use back into the home may cost from $6,000 to $15,000. Installation of a greywater treatment and re-use system including plumbing into the toilet and laundry may cost between $1,000 and $5,000.
More information
For more information about the National Rainwater and Greywater Initiative call 1800 808 571 or visit www.environment.gov.au/water.
For more information about Water for the Future call 1800 218 478 or visit www.environment.gov.au/water.
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