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Project Overview

Graywater is a term for wastewater from bathtubs, showers, bathroom sinks, laundry room sinks and most water from clothes washers. Graywater does not include wastewater from kitchen sinks, dishwashers, or toilets. If you live in the city, your water goes down the drain and into pipes. A series of sewage pipes connects your drain to the city’s water resources recovery facility. The water is treated, or cleaned, and returned to our rivers and streams for others to use downstream.

A recent state law is prompting updates to the city’s municipal code regarding graywater and graywater reuse by Jan. 1, 2026.

Graywater Reuse

“Graywater reuse” means taking graywater before it goes to the sewer, treating it and using it to flush toilets or sending it to below-ground irrigation systems to water outdoor plants and trees. Graywater is clean enough for these two uses after a small amount of treatment, but it is not safe for drinking, playing, cleaning, use in sprinkler systems or irrigation of some food crops.

The City of Boulder does not currently permit graywater reuse systems. The city is a strong supporter of water conservation and continues to advance water conservation education and programs. However, permitting graywater within the city would require development of a local graywater control program with related rules, processes and staff to make sure systems are installed properly to comply with state regulations and keep community members safe. Boulder does not currently have such a program in place.

State Legislation

The State of Colorado adopted Regulation 86 in 2015 that allows cities to permit graywater reuse systems only if the city creates a local graywater control program to ensure proper use and protection of public health. The program must oversee all regulatory activities including design review, inspection, enforcement, tracking and addressing complaints. Recent state law (House Bill 24-1362) requires that cities decide by January 2026 if they will “opt out” of creating a local graywater control program. Cities can opt in at a later time after initially opting out.

While Boulder is a strong supporter of water conservation and recognizes that graywater can be an important strategy for some communities, the city’s specific circumstances make it a less practical fit. Setting up a local graywater control program would require time and resources that are currently dedicated to promoting other water conservation programs that yield greater water savings at a lower cost. The city is in the process of proposing municipal code changes to comply with state law that will initially “opt out” of graywater reuse before January 2026. This initial code change does not prevent the city from allowing graywater reuse in the future.

Future of Graywater

Interest in graywater is continuing to grow in Colorado. The City of Boulder will continue to weigh the costs and benefits of creating a new local graywater control program. Considerations include improvements in graywater technology to reduce maintenance challenges and decrease costs, availability of resources to maintain a local graywater control program, Boulder’s unique water rights, community interest and potential for water conservation in Boulder.

If you have thoughts on graywater, please share your feedback via Bouldersaveswater@bouldercolorado.gov. Community members will have the opportunity to comment on graywater policy at upcoming public meetings.

  • Sept. 15 | Water Resources Advisory Board | Graywater code changes to comply with state law will be discussed
  • Oct. 16 and Nov. 6 | City Council will consider proposed code changes