Graywater Reuse

What is Graywater?

WaterNow Alliance and Western Resource logosWater conservation includes several types of strategies:  reduction in water losses, protection of water supplies, and beneficial reuse. Golden’s goal to reduce per capita total water use by at least 15% by 2030 primarily focuses on reducing water losses, including increasing efficiency of outdoor irrigation fixtures and preventing leaks in the system-wide water infrastructure. Graywater falls under the third strategy, beneficial reuse, and addresses water from sinks, showers, bathtubs, and laundry machines. Periodically, residents inquire about whether the City allows graywater systems or if there are incentives available.

In May 2019, the City of Golden applied for and was awarded technical assistance through WaterNow Alliance‘s Project Accelerator program to research and develop a potential graywater reuse program for residents (a $25,000 value). Through 2019 and 2020, the City worked with WaterNow and its research partner, Western Resource Advocates, to assess current efforts in Colorado and use best practices to create a potential program for Golden.

Laundry-to-Landscape (L2L) Systems

What Is A Laundry-To-Landscape System?

Laundry to Landscape DiagramThe laundry-to-landscape system is a simple system with easy distribution of graywater to multiple outdoor plants. The washing machine’s internal pump slightly pressurizes the graywater, so this system can irrigate plants across a flat or downhill yard. The washer hose is usually connected to a 3-way valve that can divert graywater either to the sewer (as your washing machine usually does) or the graywater system, where it’s piped outside with rigid pipe, such as PVC. Outside, plastic tubing is connected to the rigid pipe and T-fittings split the flow, allowing graywater to spread out and water many plants.

Pros

  • Accessible valve makes it easy to switch between the graywater system and the sewer
  • Relatively low maintenance
  • Relatively little excavation in planter areas
  • Easy to spread out water and reach many plants (up to 20 plants with a top-loading machine, up to 8 plants with a front-loading machine)

Cons

  • Involves some minor plumbing rerouting and always requires a plumbing permit and inspection
  • May require design assistance from a licensed plumber
  • Requires behavioral change to use appropriate soaps and follow up with winterization and spring activation

What does a Laundry-to-Landscape System look like?

The City has created sample designs to show what a typical system might look like and which components would be required by code. Created and reviewed by professional engineers, these specs will be useful to homeowner designers and professional plumbers alike.

What Kind of Products Can I Use With a Laundry-to-Landscape System?

Using plant-friendly laundry products is essential to ensuring success of your landscape.  Start by choosing liquid products over powder products as these usually contain less sodium. The products should be biodegradable and non-toxic, and free of salt (sodium), boron (Borax), and chlorine (most bleaches are chlorine). Laundry loads containing high levels of sodium, boron, and chlorine should be diverted to the sewer rather than the landscape where they may harm your plants. For more information, check out the California-based, Ecology Center Fact Sheet of compatible products.

How Can I Get Started With A Graywater System?

City Council approved ordinance 2143 pdf download to create a program at their meeting on September 10, 2020.

Homeowners interested in installing a graywater system can apply for consideration in Golden’s pilot graywater program Seamless Docs logo. The Office of Sustainability will cover the installation costs of three residential laundry-to-landscape systems. Installation is expected to take place in Fall 2020 or Spring 2021.

The proposed graywater program would initially be open to single family households, with potential for the program to expand to multifamily and commercial buildings in the future. When applying for a building permit, be sure to reference the Laundry to Landscape system in your description of work.

Resources

Common Terms

Graywater

Any domestic wastewater produced, except sewage. Can be used for irrigation. Includes water from sinks, showers, bathtubs and laundry machines.

Blackwater

Water from toilets, urinals, kitchen sinks, dishwashers and non-laundry utility sinks. Considered heavily polluted with biological or chemical contaminants. Not suitable for reuse unless treated by a municipal program.

Reclaimed Water

Collected from wastewater processes and treated. Can be non-potable (suitable for irrigation or industrial uses) or potable (treated to drinking water standards). Uses purple pipes.

COG Mesa

 Golden has 402 acres of open space
and maintains 253 acres of parks right within the city itself.

Additional Resources

City of Golden, Colorado
COG Mesa