Department of Utilities
Reference: Graywater Treatment Works and Use Prohibition
To: Mayor Gregory Mills and Members of City Council
Through: Michael P. Martinez, City Manager
Prepared By: Scott Olsen, Director of Utilities
Date Prepared: January 21, 2026
PURPOSE
Requesting Council consideration of an ordinance amending the International Plumbing Code as adopted by the City of Brighton to prohibit graywater treatment works and the use of graywater in the City.
BACKGROUND
Graywater is simply defined as “a portion of water used in a residential, commercial, or industrial building that may be collected after the first use and put to a second beneficial use.” An example of graywater use would be using bath water to water a garden. It is important to note that graywater treatment and use should not be confused with recycled water systems at car washes or rainwater harvesting.
House Bill 24-1362 was passed in November of 2024 and the requirements of the Bill took effect on January 1, 2026. The Bill provides statewide authorization for the use of graywater treatment works and graywater use in Colorado. Municipalities, counties and other jurisdictions must opt out of this authorization if they chose to prohibit graywater. The jurisdiction must also notify the state that they have opted out. Regulation 86 is the control regulation which places more specific requirements on graywater use and programs.
After careful analysis, City staff determined it would require the City to develop, implement and maintain a local control program that complies with Regulation 86, which would require significant investment in time, resources and staff. For example, the City would have to ensure that public health and the environment are protected from bacteria that can be found in graywater through a control program similar to permitting.
Further, the City relies on sewer return flows for our water resources portfolio, which would require looking further into the impacts of graywater on water dedication amounts and the ability for the City’s water resources to allow for continued growth.
Lastly, concerns about increased wastewater strength due to concentration and cross contamination (i.e. the unintentional backflow from a graywater system to the potable water system) exist. These concerns may also require additional staff time and expense to address.
Staff will continue to monitor regulations and interest in graywater as a water conservation tool. However, to date, staff is not aware of any request for the installation of graywater treatment works or use on a residential, commercial or industrial project.
Numerous other jurisdictions in the state have opted out of the graywater program including, but not limited to, City of Arvada, Jefferson County, City of Thornton, Arapahoe County, City of Aurora, City of Boulder, Eagle County, City of Westminster, Parker Water and Sanitation District and the City of Longmont.
FINANCIAL IMPACT
There is no financial impact of prohibiting graywater systems in the City. It is important to note that their would be significant financial impact to the utility enterprise were the City not to opt out of graywater treatment works and use.
STAFF RECOMMENDATION
City staff recommend, at a future regular meeting, Council enact an ordinance prohibiting the use of graywater treatment works and graywater use in the City of Brighton.
ATTACHMENTS
• PowerPoint Presentation