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We hear of it enough, but what is greywater, and how do you use it?

Garden hose

Conserve water in the garden by using greywater.

Credit: Wikimedia

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What exactly is greywater?

Greywater sits in the middle of the spectrum between white (fresh) and black (toilet and toxic waste) water. It's the type of wastewater you generate from household activities such a bathing and doing the laundry.

In a drought-affected, water-short country like Australia, recycling water is a way to stretch a limited resource. Greywater can be used to help maintain your garden (use it to water your plants and lawns so that fresh water isn't wasted), and treated greywater also has some limited uses inside the home.

What are the different ways of using greywater?

Greywater may be bucketed, diverted or treated.

Bucketing involves capturing small amounts of water in a bucket after use. For example, you may scoop out water from a bath to throw on the lawn or divvy up between pot plants outside.

Diversion of greywater is essentially an automated version of bucketing, where greywater is redirected outside (direct from the washing machine, for example), generally into sub-surface irrigation systems.

A greywater treatment system can be used to recycle water for use both outside and inside the home for things like doing the laundry and for flushing toilets.

Is greywater safe?

Any greywater you use may contain higher levels of chemicals and bacteria. So don't drink it, or let your pets drink it, and always wash your hands after using it.

But wastewater from showers, baths, hand basins and washing machines is perfectly safe to use on the garden - though keep in mind that you should use environmentally friendly products (soap, shampoo, detergents and the like), so that you don't harm your plants or the soil!

It's not a good idea to use kitchen wastewater, as soil organisms won't break down the food and chemical contaminants in the water very quickly.

Be sure to only use as much liquid as the soil can absorb, and rotate the areas you use the wastewater on. If the plants start to look unhealthy, or your garden begins to smell bad, then stop! And don't use wastewater on fruits or vegetables that you intend to eat raw.

Are there greywater regulations in Australia?

There sure are! (In some regions at least.) Here's a state and territory blow-by-blow:

Australian Capital Territory: The ACT government does not specifically regulate greywater. However, you are expected to comply with all relevant plumbing legislation. The Department of Health has a fact sheet available - Greywater Use: Guidelines for Residential Properties in Canberra.

New South Wales: No approval is needed for bucketing or diversion, provided the latter is installed by a plumber and meets certain conditions. The local council must approve a NSW Health-accredited domestic greywater treatment system, which a plumber must install. The Department of Energy, Utilities and Sustainability has fact sheets available.

Northern Territory: All greywater use must be approved by the Department of Health and Families, which has information available here.

Queensland: Bucketing or attaching a flexible hose to your washing machine outlet to water the garden does not require council approval, but true diversion or treatment systems must be installed by a plumber and have local council approval. The Department of Local Government, Sport and Recreation has a fact sheet available.

South Australia: As with Qld, bucketing or attaching a flexible hose to the washing machine does not require approval. Diversion or treatment systems must be installed by a plumber and approved by the Department of Health, which has fact sheets here.

Tasmania: It's best to check with your local council, but, in general, if you live in a sewered area, using greywater is not permitted. If you don't live in a sewered area, and/or can get permission from your local council, a licensed plumber must install a diversion or treatment device accredited by the Department of Justice, which has information available here.

Victoria: Bucketing is permitted, and a qualified plumber must install a diversion system but approval is not needed. Treatment systems must also be installed by a plumber, and need local council approval. The Environment Protection Authority has facts sheets here.

Western Australia: Bucketing is permitted, but a diversion or treatment system must be approved the local council and Department of Health, and must be installed by a qualified plumber. The Department of Health has a Code of Practice for the Reuse of Greywater in Western Australia.