Water advisory board votes to recommend Boulder opt out of graywater program

The Water Resources Advisory Board voted Sept. 15 to recommend that the Boulder City Council adopt municipal code amendments that explicitly opt the city out of permitting graywater systems unless the city later establishes a local regulatory program.

City utilities staff said the change is needed to comply with a 2024 state law that takes effect Jan. 1, 2026, and that the board’s recommendation will be forwarded to City Council for first and second readings on Oct. 16 and Nov. 6.

The recommendation reflects staff analysis that graywater — household wastewater from showers, sinks and laundry reused on the same property — can be technically complex to regulate. “A local graywater control program would require plan review, inspection and ongoing enforcement,” Crystal Mori, senior water resources engineer, told the board. She added that the state law flips prior rules by allowing graywater by default in new construction unless a city opts out, which obliges cities to either adopt a local regulatory program or opt out formally.

Why it matters: staff estimated that, even if the city pursued a program and uptake were relatively high, graywater would save about 1% of citywide water demand. Officials said that establishing and administering a regulatory program — and tracking supplies that can legally be used for graywater — would require additional staff resources and create ongoing compliance obligations.

Board members and members of the public asked about enforcement, public-health risks and whether household, informal reuse (for example, capturing shower warm-up water in a bucket) would be affected. “The state already has requirements that we would need to keep track of … make sure that filters are being replaced and things of that nature,” Mori said. Kim Hutton, water resources manager, said that capturing small amounts of water in a bucket before it reaches the drain generally would not meet the city’s definition of graywater because it does not enter the wastewater system: “If it’s not going into the drain and starting to become part of the wastewater treatment system, then it is not effectively graywater.”

Board member Mark McIntyre, chair of the Planning Board, raised concerns that the proposed language might read as a blanket ban on simple do-it-yourself collection during droughts. Mori and city staff said the ordinance defines graywater consistent with the plumbing code and that research exemptions (for example, a prior University of Colorado pilot) remain possible; staff also said the city can use drought-response authorities to encourage temporary capture methods in emergencies.

Staff emphasized costs to homeowners and experience in other jurisdictions. “Fort Collins did a study on return on investment of graywater systems,” Mori said. “At their current rates, they found 30 to 65 years to recover.” Board members said that low homeowner uptake and long payback periods weighed into the recommendation.

Formal action: The board approved a motion recommending that City Council adopt the proposed graywater code changes in substantially the same form as Attachment A in the meeting materials. The board did not record individual roll-call votes in the transcript; three board members were present and the motion passed. Staff noted the council schedule and urged prompt action to meet the Jan. 1, 2026, deadline.

Next steps: The board’s recommendation will be transmitted to City Council for consideration. Staff said the city can revisit the issue and develop a local graywater regulatory program later if community interest or technology and administrative supports change.

Ending: Staff said they will bring the ordinance package to council and can return to advisory boards with more detailed cost and staffing estimates if requested.