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

03.Which option suits you?

If you have access to mains water, it’s unlikely you’ll want to bother with greywater recycling unless you wish to maintain a large, thirsty garden. You’d probably be better to install a rainwater tank and pump.

But if you produce a lot of greywater, thanks to a large household, regular use of a top-loading washing machine and/or a passion for long showers, it could be worth investing in some sort of greywater recycling. Garden

The system that best suits will depend on your situation:

  • Big garden (fruit or ornamentals)
    The cheapest and simplest solution is to get a diverter and send that water to the lawn or garden through sub-surface irrigation pipes. However, a higher level of treatment will be safer and give you more options (such as also using it indoors).
  • Vegetable gardening
    If you want the water for growing herbs and vegetables you’ll need to get a higher level of water treatment to use it on the garden — and you can also use it indoors. Untreated greywater should definitely not be used on food plants that will be eaten raw.
  • Small or no garden
    If you produce a lot of greywater but don’t have much garden, you could get a treatment system that allows tPlanthe water to be used in your toilet and/or washing machine. See Greywater gardening to get an indication of garden size versus greywater required.
  • Drought-affected supply
    If you live in a drought-affected part of the country and/or have to rely on rainwater for your household water supply, a greywater treatment system could help a lot — especially when water is worth any price. If plumbed into your toilet and washing machine, you’ll save precious drinking water. It will also reduce the load on septic tanks or drought-stressed waterways. (You might also consider a waste water treatment system that handles black as well as greywater, though this is beyond the scope of this article.)
  • You want the whole green shebang
    Installing a greywater treatment system will reduce how much water you use (especially if teamed up with a decent-sized rainwater tank), reduce the amount of water going into the sewerage system, and avoid some of the cost to the community of infrastructure for providing water and dealing with waste. While it won’t necessarily save you much money, for many it’s simply buying peace of mind. And let’s face it: there’s kudos in green status symbols.

Check before you buy

Authorities are often lukewarm about the use of untreated greywater on gardens, especially in areas of high population density where potential contamination of neighbouring properties, soils and groundwater is a concern, not to mention contamination of food plants. There are certainly situations where the risks outweigh the benefits.

Check first with your local council for what’s required, and it may be able to tell you whether you’re eligible for any green rebates. You may also need approval from your council and/or water authority.

And before you order any greywater diverter or treatment system, you need to check that it’s accredited by your state health or environment department. It’s unfortunate, and perhaps ironic, that while anyone can pipe their contaminant-loaded washing machine and bath water onto the garden, systems that provide a better level of treatment — and therefore safer water — entail more bureaucratic dealings.


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