Untreated greywater can be used for garden watering if used immediately after it is produced. The waste water from kitchen sinks and dishwashers is not usually collected as it is too heavily contaminated.
Soil is very effective at filtering out many contaminants in grey water. However water containing soap or detergents does have the potential to cause soil, especially clay based soils, to lose their structure.
Water that has been used with bleach or boron compounds most often found in dishwasher detergents should not be used. Grey water should not be used for watering edible crops.
The Horticultural Trades association has useful advice on greywater use on your garden and an explanation of the restrictions imposed by a Drought Order.
