Reusing greywater to water lawns and gardens could save up to 50,000 litres of drinking water per home each year.
Greywater is recycled water from domestic use in the home. It includes water from baths, showers, hand basins and washing machines and can be used on the garden or treated and reused in your washing machine, toilet or garden. Greywater from the kitchen (including dishwashers) should not be used because the concentration of food wastes and soil organisms do not readily break down chemicals.
According to Sydney Water, “Approximately 61 per cent of the total wastewater produced by an average household can be used as greywater. Kitchen wastewater is not usually included in this amount.“How to do it now!
There are three main ways to reuse greywater:
- Bucketing – collecting small quantities of greywater in a bucket from the bath or shower and reusing it to irrigate lawns and gardens.
- Greywater diversion systems – a system installed by a plumber that redirects greywater from the shower, bath and laundry for use in the garden or lawn.
- Greywater treatment systems – a system to treat greywater to reduce solids, pollutants and microorganisms. This treated water can be used above the ground for lawns and gardens, flushing toilets and in washing machines. The system needs to be installed by a plumber, approved by the local council and serviced regularly.
Using greywater can keep your garden lush during periods of low rainfall, but you need to get it right, as it’s possible to damage your soil, plants or even put your family and pets at risk.
Greywater diversion systems
A diversion greywater system can be set up easily by installing a “diverter” to the drainage pipes from your bathroom, and laundry. However, it is recommended that you have a licensed plumber do this work. A simple start may be to use a bucket to bail out the bath or shower.
In most states you do not need permission to divert greywater from the shower and washing machine for immediate use on the garden. If you are going to install a greywater treatment system make sure the system is accredited in your state water authority and local council and that it is installed by a licensed Plumber.
Greywater treatment systems
There are a number of greywater treatment systems available that will treat the greywater so it can be stored for later use. Installation of a greywater treatment system generally requires a local council permit.
Greywater treatment systems will usually process the greywater through the following steps:
- Course filtration – Solids separation removes lint and other coarse materials to prevent blockages and fouling of the system.
- Fine filtration – Water flows down through a bed of proprietary media in the Processor. Contaminant removal is achieved through filtration, adsorption and biological treatment.
- Ultraviolet treatment – Ultraviolet (UV) disinfection completes the treatment process before the treated water is stored for recycling.
- Storage – once treated the water can be stored for reuse in flushing toilets, garden or laundry use.
- Greywater can help most plants thrive. The water from our shower, bath or laundry will probably contain soaps and detergents. These contain salts, and nutrients phosphorus and nitrogen.
- Reusing greywater directly in the garden means we are adding these nutrients to the soil. Phosphorus and nitrogen are often used as fertilisers, so the garden may need less fertiliser, or none at all. We can also choose washing powders and detergents that are low in phosphorus and salts.
- Soap may contain fats that can make the soil water repellent. You might need to use a soil re-wetting product.
- A greywater treatment system will reduce the amount of nutrients in the treated greywater.
- If you’ve been cleaning with products like bleach or disinfectants, don’t reuse the greywater.
Personal safety and health
- Do not let children or pets drink or play with greywater
- Water you hands after watering with greywater
- Do not use greywater on vegetable gardens if the crop is to be eaten raw or uncooked.
- Do not use greywater that has faecal contamination, i.e. from washing nappies, etc.
- Do not store greywater or allow it to flow into stormwater drains or other people’s properties.
Explore government rebates and assistance
The federal and most state governments offer generous rebates for installing a rainwater tank or greywater systems. Check our rebates and assistance page for more details. The Smart Watermark website lists local government rebates that may also be available.