Greywater is wastewater from household appliances such as showers, sinks, washing machines and dishwashers. It does not include wastewater from toilets.
Using household greywater can reduce your domestic water consumption and will help conserve drinkable water.
It’s important to know that using greywater can carry several potential health and environmental risks, so you need to take care to ensure that it is used in a safe and controlled manner.
Using greywater safely
Greywater contains many pollutants, such as chemicals derived from cleaning products, dirt, food and human waste. The bacteria and chemicals from these pollutants can affect the health of your family and your garden.
The health and environmental risks of greywater can never be eliminated, but you can minimise the risks by taking the following precautions:
- Ensure greywater does not contaminate any drinking water sources.
- Ensure people and pets cannot drink or access the greywater.
- Greywater use must be confined to within your property.
- Greywater must not leak into stormwater drains or waterways.
- Untreated greywater must not be stored longer than 24 hours.
- Overflow from a greywater system must discharge to a sewer or septic tank.
- Do not use greywater to water vegetable crops that are eaten raw or only cooked briefly.
- Do not use greywater that could have human waste contamination, e.g. water used to wash nappies.
- Use low-risk sources of greywater, such as water from the bath, shower or laundry rinse cycle.
- Do not use kitchen wastewater, as it is heavily contaminated with fats, greases and solids.
- It is a good idea to use greywater with a below-ground system, such as drip irrigation, as this will reduce human exposure.
- Use low-phosphorous detergents.
- Carefully monitor the impact of the greywater irrigation system on your garden.
For more information about the use of greywater, contact your local council or the Environment Protection Authority.