Using Greywater

Greywater is water generated from our homes including water from baths, showers, handbasins and the laundry.  It does not include water from the toilet or kitchen - this is classed as blackwater.  Kitchen water is usually high in fats and caustic products.

The ACT government in its 2004 Think Water, Act Water Strategy aims to increase the use of reclaimed water from 5% to 20% by 2013.  On average a two to three person household in Canberra generates 306 Litres of greywater per day from handbasins, showers, bath and the laundry.

Greywater can be a useful alternative to potable water for garden use during times of drought.  There are a number of rules to follow when applying greywater.

• Greywater should be applied below the surface under mulch (do not use it in spray or mist form)
• Untreated grey water should not be stored for longer than 24 hours
• When used in drip irrigation - use lavender coloured pipes (pipes designated for greywater use)
• It should not be applied to edible food crops eg roots and tubers, but may be used to water fruit trees
• Ensure garden safe products are used in the bathroom and laundry: choose phosphate free or low phosphate detergents and household cleaners. Many plants like Grevilleas are intolerant of phosphorous and may die if grey water is applied to them. Avoid alkaline detergents for pH sensitive plants such as Rhododendron, Azalea and Camellia. Detergents high in sodium can modify the soil composition over time, reducing the drainage capacity of soils.

>> For laundry products research

• Apply grey water in more than one spot to avoid negative effects to the soil
• Do not use if people in the house have been unwell, for example, suffering from diarrhoea

Greywater systems can vary greatly from a simple diversion system, to diversion and filtration, to advanced systems combining diversion, filtration and storage.

1. A simple diversion system using a bucket or siphon – this is an inexpensive but labour intensive solution
2. A diversion device which directs grey water from laundry or bathroom to the garden – water needs to be applied by householders to plants or lawn, or hose inserted into agricultural pipes in trenches.  This is also relatively inexpensive  but labour intensive. Diverters range in price to a couple of hundred dollars to around $1000 dollars. Diverter systems >> Ecocare Greywater >> Nylex Greywater Diverta (pdf - may take a few seconds to load) >> Greywater Saver
3. Simple filtration system using reed beds >> Reed beds for treatment of household wastewater
4. Untreated storage up to 24 hours (after this time there is an increase in odours and micro-organism growth)
5. Storage greater than 24 hours with treatment – this systems can vary greatly in cost from a system made by a householder from simple components to off-the-shelf systems.  Some systems use chemicals to aid in the purification process whilst others rely on biological actions.  All treatment systems require regular maintenance to ensure efficient operation of the system.

Average costs starts from around $11,000 for a system with additional costs for installation, plumbing and electrical works.

A number of treatment systems are commercially available in Australia:

>> Perpetual Water

>> Nubian (Oasis)

>> Every Precious Drop

>> Neco

>> Envirowater

>> Biogreen

Product disclaimer

>> Greywater guidelines for residential properties in Canberra

>> For diagrams of owner-built grey water systems

REFERENCES

Van Dok, Wendy (2002) Revised Ed. The water efficient garden. Water-efficient gardenscapes: Victoria.

Windust, Allan (2003) Waterwise house and garden.  Landlinks Press: Victoria.