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Rainwater, Graywater, and Storm Water 
DWR > Surface Water > Water Rights > Rainwater, Graywater, and Storm Water

Rooftop Precipitation Collection

Although it is permissible to direct your residential property roof downspouts toward landscaped areas, unless you own a specific type of exempt well permit, you cannot collect rainwater in any other manner, such as storage in a cistern or tank, for later use.  Please review our Rainwater Collection Informational Brochure as well as links to Colorado State University Extension's information on this topic, both of which reflect Colorado law, before completing and submitting an Application for a Rooftop Precipitation Collection System Permit.  If your well has not been registered, you will also need to Register an Existing Well before applying.

Rainwater Harvesting Pilot Projects

House Bill 09-1129, as amended by House Bill 15-1016, allows for Pilot Projects for the Beneficial Use of Captured Precipitation in New Real Estate Developments. The Colorado Water Conservation Board (CWCB) has developed criteria and guidelines for applications and the selection process for new development pilot projects to evaluate the feasibility of rainwater harvesting as a water conservation measure in Colorado, when paired with efficient landscaping and irrigation practices.

Graywater Use

Graywater is a portion of the water used in a residential, commercial, or industrial building that may be collected after the first use and put to a second beneficial use. Though recent changes to Colorado statues and regulations provide a framework for the use of graywater, graywater use remains subject to compliance with local regulation and Colorado’s water rights system. Jurisdictions at the city, city and county, or county level must create a graywater control program and adopt an ordinance or resolution to allow graywater use prior to graywater use in the jurisdiction. Contact your local government office to find out if your jurisdiction has a graywater program.

Graywater use is subject to compliance with Colorado’s water rights system, including well permit conditions and water supplier restrictions.  Please see DWR’s 2011 Administrative Position for Graywater Reuse or contact DWR to learn more about the interactions between graywater use and Colorado’s water rights system.

Additional resources:

Storm Water Management

Senate Bill 15-212 exempts many storm water detention and infiltration facilities from administration in Colorado’s prior appropriation system so long as the facilities meet specific statutory criteria, including that they do not divert the water for beneficial use, that ground water is not exposed, and that new facilities are properly designed and noticed.  For more information on the notice process, see the Colorado Stormwater Detention and Infiltration Facilities Notification Portal.  For more information on the statutory criteria please see DWR’s Administrative Statement.

Landscaping that is planted on roofs (green roofs) is allowable as long as the landscaping intercepts only precipitation that falls directly onto the landscaping. The landscaping may not intercept and consume concentrated flow and may not store water below the root zone.  Please see DWR's Administrative Statement for additional details.

(Page Revision: 2/24/2016)