Greywater – another alternative

Greywater is wastewater from the hand basin, shower, bath, spa bath, washing machine, laundry tub, kitchen sink and dishwasher.
Domestic greywater originates from non-toilet plumbing fixtures only.

It is important to consider the quality of greywater from different sources to ensure that its use does not pose a risk to public health or the environment.

Greywater from the kitchen is not recommended for use.
Kitchen greywater may be heavily polluted with food particles, oils, fats and other wastes, which can promote and support the growth of micro-organisms and solidify, causing blockages in the greywater system.
It is often chemically polluted with detergents and cleaning agents, particularly those from dishwashers, which are very alkaline. Over a period of time these contaminants may damage the soil.
It may also contain harmful bacteria.

Greywater from the bathroom is suitable for use. On average, a two to three person household generates 185 litres of greywater per day from the hand basin, shower and bath.
The chemical constituents of bathroom greywater include soap, shampoo, hair dyes, toothpaste and cleaning chemicals. Greywater from hand basins is more polluted than bath or shower greywater, but is much lower in volume.
Some of these contaminants act as plant nutrients and can be beneficial in the garden in low concentrations, but others can adversely affect plants or soil structure and are difficult to remove.

Greywater from the laundry is suitable for use.
On average, a two to three person household produces 121 litres of greywater per day from the laundry.
Bacteria numbers in laundry greywater are not usually high, except when nappies are washed. Greywater from nappy washing is not recommended for use.
The chemical contaminants of the wash cycle water are soap, salt, sediment and organic material. (Using phosphate-free laundry liquid is easier on the environment). Washing machine rinse cycle water is of a better quality than wash cycle water. You may wish to consider only using water from the rinse cycle.

Diversion of untreated greywater
The simplest systems involve diverting greywater from the laundry and/or bathroom directly to the garden or lawn.
This can be achieved by:

• Using a bucket or siphon to transfer water.
• Connecting the washing machine discharge hose to a pipe leading to the garden.
• Fitting the laundry tub waste pipe with a hand operated diversion valve. You can then easily switch the plumbing diversion device to divert greywater, by gravity, from the laundry tub through a hose to the garden instead of the sewer.

It should be noted that any work conducted on the water supply, sanitary plumbing or drainage systems is to be carried out by a licensed plumber or drainer.

Also, check greywater usage guidelines with your local council.

It is important to understand the potential health risks from misuse of greywater. More information is available through NSW Department of Health website at: www.health.nsw.gov.au

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