Understanding greywater

Most people have a plentiful supply of greywater around the home, and if utilised properly, it could save thousands of buckets of drinking water. Read our handy advice on recycling your greywater below.

Greywater is the wastewater from the shower, bath, hand basins or washing machine and doesn’t include water from the kitchen sink or from toilets (known as black water). It is considered to be safe, provided that it is used in the appropriate way.

Greywater can contain certain disease-causing microorganisms, fats, oils, detergents, salts and more that are derived from the home and personal cleaning. If you switch to greywater-safe detergents and cleaning products, this should minimise the impact on your wastewater.

Using greywater can be as simple as bucketing it out by hand into the garden, or as complex as installing an automatic diversion, treatment and irrigation system.

Working safely with greywater

There are a number of do's and don’ts to be taken into account when installing and using a greywater system. These vary depending on the type of system used and the level of treatment.

What to do
Use a licensed plumber to install the diversion system.
Use low-risk sources for water diversion systems such as bath, shower and laundry rinse water (Laundry wash water is much higher in detergent concentrations than rinse water).
Be aware of biodegradable labelled products (e.g. soaps and detergents). Liquid-based products are generally better (check the ingredients on the packaging);.
Only divert greywater in dry conditions, in quantities that can be taken up by plants & soil (i.e. avoid over-irrigation and runoff).
Apply with buckets or watering can onto the garden or use subsurface garden irrigation only (to council setback requirements).

What not to do
 Use untreated greywater from the washing of nappies or soiled clothing.
Use untreated greywater when a resident has diarrhoea or is sick. 
Use untreated greywater generated by cleaning in the laundry or bathroom, or when using hair dye or other chemicals.
Use untreated greywater generated by washing rags used for painting or for maintaining machinery.
Store untreated greywater for more than 24 hours, as it illegal in most states.
Use kitchen water for greywater as it is heavily contaminated with fats, greases and solids.
Apply untreated greywater to vegetable gardens. • DON’T over water with greywater (any water) as it can raise the local water table or cause excess to run off into other properties or waterways.
Use water from toilets for greywater.
When installing a greywater treatment system and using treated greywater:
What to do
Select garden-friendly detergents that are biodegradable and low in phosphorus, sodium, boron and chloride (select liquid washing detergents, as they are comparatively low in salts).
Monitor plant and soil response to treated greywater irrigation.
Ensure that regular maintenance of the treated greywater system is undertaken.
What not to do
Irrigate with treated greywater during rain. 
Use treated greywater to top up rainwater tanks or swimming pools.
Irrigate with greywater if the premise is located on an aquifer that is used for drinking water.
Use treated greywater on plants that will be eaten raw or where fruit has fallen to the ground.
Use treated greywater so that it flows into the streets or down stormwater drains.
Let treated greywater go beyond the premise and cause a nuisance to neighbours. 
Use water from the kitchen, hand basins or toilets for treated greywater.