Guide to greywater systems

We take you through greywater options, from simple diversion to 'Class A' treatment systems.
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  • Updated:2 Jan 2008

01.Greywater systems


In brief

  • Some greywater systems cost less than $1000, some cost over $10,000, and water quality varies accordingly.
  • There are two main options: diversion devices and treatment systems. The best option for you will depend on how much greywater you produce, the size of your garden, and your budget
  • Greywater recycling is not for everyone — for some people the costs (and risks) will outweigh the benefits.

With water restrictions operating in many parts of Australia, people are looking at ways to save water or save their garden — or both. Rainwater tanks are one option (if you’re getting any rainfall). Recycling greywater is another logical option: after all, you don’t need drinking-quality water to water the garden or flush the toilet.

Please note: this information was current as of January 2008 but is still a useful guide to today's market.

What is greywater?

  •  It's the waste water from showers, baths, spas, handbasins, laundry tubs and washing machines. Water from dishwashers and kitchen sinks is often referred to as dark greywater, because it has a higher load of chemicals, fats and other organic matter. Water from toilets is called black water.
  • It’s estimated that just over half of total household water could be recycled as greywater, saving potentially hundreds of litres of water per day.
  • Greywater 'systems' range from a simple hose diverting water from the washing machine to the garden, to treatment systems that treat greywater for use in your washing machine or toilet, as well as the garden.

Risks to consider

Using untreated greywater on the garden can be relatively cheap and easy, but can be risky for several reasons:

  • Potential exposure to disease-causing pathogens.
  • Damaging salts and chemicals could kill your plants and ruin the soil.
  • Run-off could escape your boundaries and create problems for neighbours.

CHOICE verdict

Installing a greywater treatment system will give you safer water and more options to reuse it, but it’s expensive and needs regular maintenance. Buying one probably won’t save you much money on water costs over time, but it might save your garden — a valuable part of your house — if you can’t use tap water in times of high-level water restrictions.

Not only your garden will benefit. Any sort of greywater recycling will reduce how much water you use and the amount of water going into the sewerage system. Combined with water conservation measures and a rainwater tank, you’ll be doing your bit for the environment.

More information

Greywater is a complex substance and there are many things to consider if you’re to use it safely and to maximum benefit. The NSW Department of Water and Energy has a very comprehensive set of guidelines for greywater use in households, including figures to help you calculate your water use and needs. There’s a link from its greywater main page.



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