Greywater

What is greywater? Greywater is all the water coming from fixtures in the house such as shower, bath and laundry, but excluding the toilet. Kitchen sink and dishwasher water should also be excluded because they can contain grease and caustic detergents making them less suitable for reuse. Is it legal to use greywater on my garden? Yes, provided you have approval from your local council. You must also use a licensed plumber for connecting the system to household plumbing. What are the benefits of using greywater? Using greywater on your garden will save water, and because your water account is now much more based on water usage than previously, this means you will also reduce your water account. A trial on greywater reuse carried out on four houses in Melbourne by Victoria University resulted in water savings of between 32,000 litres and 57,000 litres per year. What are the risks of using greywater? Greywater contains large numbers of bacteria that may include disease-causing organisms. Care needs to be taken to ensure there is no contact between other people and your greywater. Greywater contains a number of pollutants that can damage the environment if the greywater is not used responsibly. The pollutants in greywater include organic matter, nutrients, salts and detergents. Irrigation with greywater has been used successfully, but there is a risk that some sensitive garden plants may be affected by long term use of greywater. How can I use greywater safely? The following points outline some basic features of a greywater system. This list is not comprehensive and you must obtain approval from your local council for any system you propose to install. To reduce the risk of spreading disease, greywater should be distributed around the garden by a below ground system, such as drip irrigation. The dripper lines need to have adequate cover. A thick layer of mulch on the garden will assist. A screen or filter will be needed to avoid clogging of the irrigation system by lint and hairs. Front loading washing machines are most suitable as they produce less lint and also use less water than top loading machines. The system used to collect greywater from the house and divert it to the garden must be fail-safe, so that greywater is automatically diverted to the sewer if a blockage or other system malfunction occurs. This will prevent greywater running over the ground into stormwater drains. A suitable system is shown in "Model Guidelines for Domestic Greywater Reuse for Australia" . The greywater system must have a valve or some other means to allow greywater to be diverted to the sewer when it is too wet to go to the garden. Care will need to be taken when choosing detergents and other household cleaning products. Use of non-phosphorus containing detergents (these have a "NP" symbol on the pack) is advised. Our Customer Contract states (Clause 6.3.1): "Customers can: collect and use rainwater for their own use; install a composting toilet which does not require connection to Yarra Valley Water Ltd's water or sewerage systems; divert domestic wastewater for non-drinking purposes, such as watering the garden, provided that this is done in accordance with Part 12A of the Building Act 1993." Clause 6.3.1 adds "There are health and/or environmental considerations to be taken into account in installing these systems and local council or other approval may be required." References D Christova-Boal et al, "Installation and Evaluation of Domestic Greywater Reuse Systems" Report No 3/1995, Victoria University of Technology, December 1995. "Model Guidelines for Domestic Greywater Reuse for Australia" Urban Water Research Association of Australia, Report No 107. March 1996.