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Using greywater on the garden

Greywater use around the home
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Using greywater on the garden is an ideal way to keep it alive without relying on precious drinking water. But because greywater can potentially harm garden plants, it is recommended that you use collected rainwater first. If the water level in your rainwater tank is getting low, alternate greywater on the garden with collected rainwater.

Greywater is mainly collected from baths, showers, hand basins and washing machines, but excludes water from the toilet. Water from kitchen sinks and washing machines is also technically greywater, however, care should be taken before use as the high concentration of food wastes and chemicals could harm some plants.

There are different types of greywater systems and advice on which one to use varies according to where you live.

For general information on greywater systems, click here. Specific information on the types of greywater systems appropriate for residents in NSW and Victoria is also available.

Here is a general list of garden greywater use "do's and don'ts" which apply to all residents. Print it and keep in a safe place as a handy reference source.

Do
  • Use low phosphorus detergents
  • Diverted greywater (untreated) should only be used on the garden
  • Apply diverted greywater to the garden by a below ground seepage pipe. This will reduce human exposure to the water.
  • Use greywater only during prolonged warm, dry periods: use only what you need to meet the plant's water requirements
  • Ensure greywater is diverted to the sewer during wet periods
  • Install a diversion system that is 'fail-safe', where the greywater will automatically be diverted to the sewer if the greywater system blocks or malfunctions
  • Stop using greywater if you smell odours and your plants do not appear to be healthy
  • Wash your hands after watering with greywater and after gardening in greywater irrigated areas
  • Use less fertiliser when irrigating with greywater
  • Ensure greywater does not contaminate any source of drinking water: extreme care must be taken to ensure there is no cross-connection between the greywater re-use system and the drinking water supply
 Don't
  • Never water vegetable gardens if the crop is to be eaten raw
  • Never use greywater that has faecal contamination, for example, wastewater used to wash nappies
  • Never store untreated greywater for more than 24 hours
  • Never drink greywater or allow children or pets to drink or play with greywater
  • Never allow greywater to flow beyond your property boundary or enter stormwater systems
  • Do not use kitchen wastewater (including dishwashers) - it contains highly concentrated food wastes and chemicals that are not readily broken down by soil organisms
  • Do not allow greywater to pool or stagnate as this will attract insects and rodents, which may transmit disease.

Use a bucket to get greywater onto the garden...

One of the cheapest, quickest and easiest ways of getting greywater onto the garden is with a bucket.
  • Stand it in the kitchen sink to collect cold water whilst you wait for hot water to come through.
  • Use a bucket or container to wash vegetables and fruit as the dirty water can safely go on the garden. Don't use dishwashing water as it contains high levels of oil, grease and food scraps (and alkaline salts if using a dishwasher).
  • Put a bucket in the shower to catch cold water before it warms up.

Here are a few safety tips when using buckets to water your garden:-
  • Don't overfill the bucket - a full 10 litre bucket weighs 10kg and is a potential hazard especially when moving around slippery surfaces such as the shower and bath.
  • Whilst you shouldn’t water in the middle of the day, don’t leave greywater in the bucket for more than 24 hours as it could become a potential health hazard.
  • A small bucket could be fatal for a young infant if they explore it on their own and fall into it - store it in an appropriate place well out of reach.

The preference for greywater sources to use in the garden is based on the quality of the water and possible chemicals in it. Use the vegetable rinse water first, then bath and shower water, then laundry rinse water and laundry wash water last.

Useful information sources


For more detailed advice and a list of sodium and phosphorus levels in washing detergents, check out