“Grey” water: a clear winner

“Grey” water: a clear winner

Grey water—or the wastewater from showers, baths, washing machines and other household utilities—has suddenly gained attention as a tremendous “untapped resource”!

The Greywater Saver is inexpensive and efficient

In the few years since grey wastewater was approved for recycled use around the home, systems that divert both treated and untreated water from washing machines, dishwashers, showers and similar devices have penetrated mainstream markets.

Doubts still linger, however, in the minds of some plumbers, retailers and consumers about the appropriateness and sanitation of general-purpose grey water.

EPA Victoria, as the peak environmental protection authority in the State, has itemised some clear “Dos and Don’ts” about grey water usage that have national relevance, however retailers should check with their local authority in case different regulations apply.

As a rule of thumb, EPA Victoria authorises the use of untreated wastewater from baths, showers, hand basins and washing machines. Other sources of household wastewater, such as toilets, kitchen sinks and dishwashers, should not be used because of food particle and chemical contaminations.

Grey water should be used on general garden areas and not on vegetable gardens, particularly if legumes are to be eaten raw.

In addition, untreated grey water should be “diverted” rather than “stored”, as long-term reserves can encourage the proliferation of hazardous pathogens. A 24-hour storage limit is recommended.

Sydney Water also endorses the use of grey water, however the organisation also stipulates that untreated grey water should be used immediately rather than stored, preferably in combination with a screen filtering system to remove solids.

Consumers who wish to spend a little more on their grey water units should consider systems that treat wastewater so that it can be stored safely for later use.

Devices used for treating grey water include wetlands, intermittent sand filters, soil filters, grey water septic tanks and aeration systems.

The major point to note is that advanced grey water treatment and storage facilities are permitted for domestic applications—provided the devices meet strict standards of efficiency.

Visitors to www.sydneywater.com.au can view specific recommendations about more sophisticated devices that treat grey water to acceptable standards. The site also contains many interesting statistics about household water consumption and the savings that can be achieved by using grey water—See Figure 1.


Figure 1: Household Grey Water Sources
(Daily outputs: four-person family)
Hand Basin31
Bath & shower256
Source: Using Grey Water in Your Garden, Sydney Water