Laundry to Landscape

L2L graywater systems are allowed for use in single-family residences in Denver, however; L2L graywater can only be used to water the landscape with mulch basins. Flood, spray, or drip irrigation methods are not allowed. L2L graywater systems are not allowed on properties used as vacation rentals.

The water from L2L graywater systems can be used to irrigate decorative landscape plants, fruit and nut trees, and vegetables for your own use. Do not use graywater to irrigate root crops, sprouts, and leafy greens and always wash fruits and vegetables with potable water prior to consumption.

Don’t use water from your L2L graywater system when it’s raining, the soil is saturated or frozen, or when plants are dormant. 

Detergents and other products used in your laundry may contain chemicals that can harm your landscape plants and soil health.

• Make sure that any products used in your laundry are biodegradable and non-toxic. In addition, they should be low in salts (sodium) and free of boron (borax), two common ingredients that are non-toxic to people but are harmful to plants and/or the soil.
• Don’t use chlorine bleach; it is harmful to plants and should be diverted with any other harmful products to the sewer.
• Use a hydrogen peroxide-based bleach, a less harmful substitute for chlorine bleach.

Soils in Colorado tend to be alkaline (high pH), and many detergents are alkaline. As a result, when selecting plants to be irrigated with graywater, it’s a good idea to select native plants that are appropriate for your area and are alkaline and salt tolerant.

Suggested plants include:

• Oaks
• Honeysuckle
• Roses
• Juniper
• Bearded Iris
• Bermuda Grass
• Black-eyed Susan

If your plants are showing signs of stress, consider discontinuing the use of graywater and irrigating with potable water until the plants have recovered.

Laundry to landscape systems are relatively inexpensive and easy to install and permits are available online.

• Avoid contact with graywater, or soil irrigated with graywater. Graywater contains pathogens that can make you ill.
• You may use graywater for landscape irrigation but use it in a way that it does not pool or run off your property.
• Graywater from L2L systems must be distributed to a mulch basin or sent to the sanitary sewer immediately. Storage of graywater from L2L systems is not allowed.
• Graywater cannot contain hazardous chemicals such as antifreeze, mothballs and solvents. 
• Do not include wash water from greasy or oily rags in your graywater. Graywater from washing diapers or other infectious garments must be discharged to the sanitary sewer.

When determining the location for graywater irrigation, remember that it cannot be in a flood plain or a flood zone. Graywater may only be used in locations where groundwater is at least five feet below the surface.

Detailed requirements for setbacks and subsurface system depths can be found in Denver’s Rules and Regulations Governing Graywater Treatment Works.(PDF, 1MB)

Detailed design requirements can be found in Denver’s Rules and Regulations Governing Graywater Treatment Works.(PDF, 1MB) Laundry to landscape systems are referred to as "Category A1."

• Laundry to landscape systems must have a design flow greater that the calculated peak graywater production. The design flow for a single family laundry to landscape graywater system for subsurface irrigation is limited to 250 gallons per day (gpd) or less. 
• Laundry to landscape graywater systems are required to have a valve that allows for diversion of graywater to the sanitary sewer when needed.
• L2L systems should be vented with an auto-vent or air admittance valve.
• All pipes carrying graywater must be clearly labeled. Labeling eliminates confusion between graywater, drinking water, and wastewater pipes.

Brochure English(PDF, 5MB)

Brochure Espanol(PDF, 51MB)

Colorado Water Quality Control Commission- CDPHE Reg. 86 - Graywater Control

Local Municipality information: Graywater is currently allowed in the City and County of Broomfield, Town of Castle Rock, Pitkin County, City of Golden, City of Grand Junction, and Larimer County. The City of Fort Collins, La Plata County and other counties are working on local graywater ordinances.  Check your local municipality for more information.

Denver’s Rules and Regulations Governing Graywater Treatment Works(PDF, 1MB)

About Greywater Reuse, Graywater Action

Greywater Central, Oasis Design

Compatible Cleaning Products, Ecology Center

Greywater Compatible Soap and Detergent Info, Rainwater Harvesting for Drylands and Beyond

Greywater, Green Landscape, by Laura Allen, Storey Publishing

Graywater Systems Fact Sheet, Utah State University Extension

Plant Friendly Soaps that are Safe for Graywater Irrigation, This Old House 

Soil and Greywater Constituents of Interest, Greywater Action

Water Conservation Programs, Santa Clara Valley Water District