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Q.
What is grey water?
A.
Grey water can be classified into to groups; Light and Dark. Dark grey water is the wastewater
generated from kitchen sinks and dishwashers. It has a Fat, Oil, Grease content (F.O.G.) Light grey
water is the wastewater generated from the use of the shower, bathtub, hand sink, and laundry.
Q.
Is grey water different from wastewater?
A.
Yes. Household wastewater, also known as sewage, is composed of two distinct sources:
"Black water" is wastewater contaminated by feces or urine, and includes wastewater from the toilet,
urinal, or bidet.
"Grey water" is the remaining wastewater coming from the laundry, bathroom and kitchen.
Q.
Why should I reuse grey water?
A.
Grey water is a significant water resource, provided it is managed in an environmentally respon-
sible manner, and public health and the health of the household are protected. By capturing grey
water and using it in an appropriate manner as an alternative to your water supply, you can reduce
your water consumption. Your water account will reflect this reduction in water use and there will
also be positive environmental outcomes.
Q.
Is it safe to reuse grey water?
A.
Yes, when first disinfected and used in an appropriate way. Grey water can contain disease-
causing micro-organisms such as bacteria, protozoa, viruses and parasites. It may also contain fats,
oils, detergents, soaps, salt, nutrients, food and hair derived from household and personal cleaning
activities. These constituents can pose both health and environmental risks. However, the public
health risks associated with on site reuse of domestic grey water are considered low, as the source
of the contamination would be from the immediate family. Other sources of transfer of pathogens
around the immediate family are considered a higher risk, such as direct contact or sharing of food
and utensils. Similarly, the risk of environmental damage from the careful use of grey water is low.
Q.
How can I reduce the risks associated with grey water reuse?
A.
The following measures will reduce the health and environmental risks associated with the use of
grey water:
•
Do not use sprinklers to distribute grey water.
•
Use subsurface irrigation systems.
•
Do not spray grey water directly onto food plants.
•
Do not put grey water on lawns where children are likely to play.
•
Do not irrigate with grey water during periods of wet weather.
•
Do not allow grey water to enter the storm water system.
•
Make sure grey water does not create a nuisance, for example through odors or ponding.
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15.0 Frequently Asked Questions
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