Model ordinance to manage permissive graywater standards in 2026

“Graywater” is wastewater collected from certain sources that is reused for limited purposes. Since 2013, graywater systems were only permissible when allowed by municipal ordinances. Beginning Jan. 1, state law will permit collection, treatment, and use of graywater in new construction except where the municipality adopts a local prohibition by ordinances. Local ordinances can restrict the use and treatment entirely, allow only specific uses, and authorize construction of treatment works in existing buildings.

CML has prepared a model ordinance to help members maintain the current prohibition as they explore how to implement graywater standards locally. If an ordinance is not adopted or if graywater is permitted locally, the municipality must adopt building codes to prevent graywater from entering a potable water system and must report to the local water utility any planned installation of graywater systems that require backflow prevention cross-connection control devices.

The model ordinance is not legal advice. Consultation with your city or town attorney, water and wastewater providers, and building officials is advised. More information on graywater can be found in Regulation 86 of the Water Quality Control Commission, Colorado Department of Public Health & Environment (5 CCR 1002-86 (2023)).