Wastewater Management Program, WA State Department of Health

Grey water - Page 4

To Greywater Table of Contents Printable Greywater Factsheet (PDF 164 kb)

Handle Greywater Safely

DO NOT drink greywater or apply it on anything that may be eaten, including root crops such as potatoes or carrots.

DO NOT water lawns with greywater using a sprinkler, or use greywater to wash patios, walkways or driveways.

Picture dipicting: Do not spray greywater on any plants that will be eaten.

		greywaterfacts
		Did You Know.......?
		•	Greywater makes up the largest portion of wastewater from your home…up to 40 gallons per person each day.
		•	Greywater systems must irrigate below the ground surface by using a drainfield or a suitable drip irrigation system to reduce health risks.
		•	Greywater systems are usually cheaper and easier to install during construction of a new home. Re-plumbing an existing building can be expensive and may be impractical. If separating greywater from blackwater is a problem, you might want to consider using a Subsurface Drip System (a type of septic treatment system).
		•	Subsurface irrigation with greywater offers a way to conserve water. However, greywater may not meet all of your landscape irrigation needs all year round. Subsurface irrigation with greywater is different from Onsite Subsurface Drip Systems.
		•	Some chemicals in greywater can be harmful to plants. For example, liquid detergents generally have less sodium than powdered detergents and are recommended when irrigating with greywater. (For more information about using greywater for subsurface irrigation, see Water Conserving On-Site Wastewater Treatment Systems RS&G at: http://www.doh.wa.gov/ehp/ts/WW/pubs-ww-rsg.htm#waterconserving_rsg.

howsafelyinstallgreywater

How do I safely install and use a subsurface greywater irrigation system?

	1 Contact your county health agency for:
		·	Wastewater Treatment System permits (grey-water is wastewater),
		·	Design requirements,
		·	A list of qualified Designers and Installers.
	2	Develop a design that matches your specific needs and options for greywater use. The design of the system will depend on:
		·	The source and characteristics of the greywater,
		·	The physical characteristics of the site,
		·	A landscape design taking into consideration the kinds of plants and how tolerant they may be to greywater.
		·	Local code requirements,
		·	How, when, and where the greywater will be used.

	3	Apply greywater safely by:
		·	Irrigating with greywater 6" below the surface of the ground,
		·	Irrigating ornamental landscapes such as shrubs, trees, and flowers,
		·	Regularly checking your greywater system to be sure it is functioning properly.

Picture of an asbuilt drawing of a home, showing the location of a subsurface irrigation system.