Grey Water Use & Washing Agents
Household Greywater Reuse
Greywater (all non-toilet household wastewater) can be a good water resource during times of drought and water restrictions, but its reuse can carry health and environmental risks.
Greywater can be reused following a few simple steps with readily available systems. A number of products are now on the market that enable access to greywater from domestic plumbing situations. These products are designed for immediate greywater reuse.
Please check with your local / State Government (public health department, environmental protection agency and plumbing authority) as to the plumbing regulations within your area for the possible use of Greywater.
Greywater Reuse - The Do's And Don'ts
Greywater - Only use wastewater from baths, showers, hand basins and washing machines (preferably the final rinse water). Only use grey water on the garden and rotate which areas you water. Only apply enough water that the soil can absorb
Suitable Greywater Washing Agents
What washing agents can I use in greywater?
Greywater is used water from your laundry or bathroom. Many people collect greywater and bucket it onto their garden or install a specialised greywater system to recycle water. When using greywater on the garden, consider the type of soap, washing powder or liquid you use. Many contain ingredients that will affect your plants and soil.
Salt
Salt (sodium and chloride) is a by-product of the manufacture of washing agents. It is included in powders as a filler. There is generally less salt in concentrated powders, and even less in liquids. The graphs below can be used as a guide to salt contents of washing agents. Excess sodium in a clay soil can be amended with the addition of gypsum and compost.
Phosphorus
Too much phosphorus in greywater can be toxic to native plants, proteas and cause pollution of our waterways. It can also cause iron deficiencies in plants. Choose a washing agent that has low phosphorus. The graphs below may be used as a guide.
pH
Greywater can raise the pH, in other words, make the soil more basic (the opposite of acidic). This will tend to cause iron deficiency in plants, seen as yellow new leaves, sometimes with green veins. If you notice these symptoms, you should have the soil around the affected plant(s) tested. If the pH is high, sulphate of iron treatments will gradually reduce the pH.
Others
Bleaches (such as hair dyes and nappy wash) and disinfectants (including eucalyptus and tea tree oil) can detrimentally affect the health of soils by killing soil organisms.
Soaps
If you are using shower or bathwater on the garden, fats from soaps can make the soil water-repellant. The soil will benefit from an application of a soil rewetting agent every 6 months.
Other Useful Links - Greywater reuse
http://www.greywaterreuse.com.au/
Australian Rainwater Industry Development group