If you plan to use graywater from a laundry to landscape system for irrigation, you should be aware that laundry detergents may contain chemicals that can be harmful to your soil and plants. Here are some things you can do to help improve graywater quality and ensure your soil and plants remain healthy and hardy:
- Use a liquid detergent. Liquid detergents contain fewer salts than powdered detergents. Salts can be harmful to plants.
- Bypass your water softener. Water softeners add sodium which can reduce soil’s ability to absorb water.
- Use biodegradable detergents and detergents without boron. At low levels, boron can give plant leaves a burnt appearance and at higher levels can be toxic.
- Divert wash water from laundry loads containing high amounts of fecal matter (such as diapers) to the sanitary sewer. Fecal matter may contain disease-causing microorganisms.
- Avoid using wash water with chlorine-based bleach for irrigation. Chlorine based bleach can damage plant foliage. If you must use bleach, use a non-chlorine bleach such as hydrogen peroxide.
- Avoid using products that contain antimicrobial compounds.
- Avoid contact with graywater. Graywater may contain bacteria and disease-causing microorganisms that can make you or your pet sick.
- Graywater should not be used when outdoor temperatures are below freezing, soils are frozen or when it is raining. Divert graywater to the sanitary sewer at these times to avoid damaging your graywater system and / or releasing graywater to the environment.
Colorado Graywater. Laundry to Landscape Best Management Practices. 1 page.
University of California Vegetable Research and Information Center. Using Household Waste Water on Plants. University of California, Division of Agricultural Sciences, Leaflet, 2968, 2 pages. Available at: http://vric.ucdavis.edu/pdf/fertilization_Householdwastewater.pdf
Committee on the Beneficial Use of Graywater and Stormwater (2016). Using Graywater and Stormwater to Enhance Local Water Supplies: An Assessment of Risks, Costs, and Benefits. Water Science and Technology Board; Division on Earth and Life Studies; National Academies of Sciences, Engineering, and Medicine. The National Academies Press, 224 pages. Available at: http://www.nap.edu/21866.