The Department of Health currently has a greywater reuse policy Greywater Reuse in Sewered Single Domestic Premises – April 2000 which is available at the NSW Department of Health.
Greywater can contain disease-causing organisms, detergents, soaps, nutrients, oils, salts and particles of hair, food, lint etc. Unless properly managed, these characteristics can pose a risk to health and the environment. This means that long term sustainable greywater reuse should be in accordance with the greywater reuse policy and as required under current legislation.
New South Wales is experiencing water restrictions due to current drought conditions and the critically low levels of surface water storage. It is recognised that in times such as these many householders like to conserve water by reusing their greywater on their gardens.
Many of the alternatives being put forward have the potential to pose a public health risk. Most Public Health Units have received enquiries from councils and the public regarding the reuse of household grey water. This information sheet provides guidance on how grey water can best be reused for watering gardens and lawns. This advice is intended for the duration of the current water restrictions only.
Greywater cannot be re-used for drinking or other domestic uses such as food preparation, ablutions, washing clothes, car washing, and topping swimming pools. Recycling of other household effluent such as black water (toilet waste) should not occur due to significant risks to human health. Some types of greywater may be used relatively safely for garden watering as described below.
Wastewater from the kitchen sink (apart from final rinse water) and dishwasher should not be reused as these can contain heavy loads of organic material, fats and caustic additives. Greywater from the bath, shower, laundry trough and washing machine (final rinse water only) and wash hand basin are the most readily available sources of greywater that can be reused. Only by using a bucket, or similar receptacle, can these types of greywater be collected and applied to garden or lawn areas. This manual application will assist in keeping health risks to a minimum. Drainage systems must not be altered to allow the direct diversion of greywater to the ground surface.
If the house is serviced by reticulated sewerage, it is important not to reuse all the greywater. Some greywater is needed to help flush sewer pipes to prevent blockages.
Further Information
For further information and advice contact Auburn City Council's Environment & Health Unit on (02) 9735 1222 or the Western Sector Public Health Unit on (02) 9840 3603.