Rainwater & Storm Water

Rainwater Collection & Beneficial Use

Storm water is administered within the Priority System of water rights. The following are special considerations for certain storm water facilities within the priority system.

 
Green Roofs

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. See further discussion in DWR’s Administrative Statement Regarding the Management of Storm Water Detention Facilities and Post-Wildland Fire Facilities in Colorado.

 

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. Colorado Water Conservation Board (CWCB) developed criteria and guidelines for the application and 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. Approved Pilot Projects may harvest without replacement a volume of rainwater runoff equivalent to the pre-development consumptive use of the native vegetation.

Informational Guides & Brochures

 

 

Rainwater Collection & Rain Barrels

Rainwater collection is allowed on residential properties under certain conditions.

Rain Barrels

Precipitation can be collected in rain barrels from the rooftops of certain residential properties.
 

  • Who can collect water under this law? Any single family residence or multi-family residence with 4 or fewer units. Each home in a row of homes joined by common side walls, such as duplexes, triplexes, or townhomes, is considered a single family residence.  See the Rainwater Collection Information Table for additional details.
  • Do I need a permit through DWR before I start collecting precipitation in rain barrels? No permit or other approval is required for capture and use of precipitation in rain barrels with a combined storage capacity of 110 gallons in accordance with HB16-1005.
  • Where can I collect the water from? From the roof of a building that is used primarily as a residence.  
  • How much  water can I collect? You can fill and refill two rain barrels with a combined storage capacity up to 110 gallons throughout the year.
  • What can I collect the water in? Water must be collected in rain barrels (up to 110 gallon total capacity) with sealable lids
  • What can I use the water for? Outdoor uses, such as lawn and garden irrigation, on the property where the water was collected.  Though the rainwater can legally be used for a variety of outdoor uses (car washing, livestock watering, hot tub filling, irrigation, etc.) rainwater users should evaluate the quality of the collected rainwater to ensure it is appropriate for the proposed outdoor use.  The water cannot be used for drinking water or indoor household purposes.
  • Will standing water in the rain barrels create a mosquito problem?  Rain barrels must have sealable lids to prevent insects or other pests from using the stored water.  See the Colorado Department of Public Health and Environment's Residential Rain Barrels Best Practices Flyer above for more information.
     
Additional Allowances for Rainwater Collection on Properties with Residential Wells

In addition to the 110 gallons of precipitation that can be collected and stored in accordance with HB16-1005 (described above), certain residential properties that have a residential well, or that could qualify for a residential well, may be eligible to collect more than 110 gallons of precipitation in accordance with Senate Bill 09-080.

  • Who can collect water under this law? (SB09-080): Any residence that has, or can qualify for, an exempt residential well permit through the Division of Water Resources.  This law operates independently of HB16-1005. See the Rainwater Collection Information Table above for additional details.
  • If I do not have a well or well permit, how do I know if my property qualifies for a well permit? This will be determined by the Division of Water Resources (DWR) when you apply for the required precipitation collection permit.
  • Do I need a permit through DWR before I start collecting precipitation? Yes, before you begin to collect precipitation in connection with an exempt well permit, you need to obtain a rooftop precipitation collection permit.  Check out the Rainwater Collection on Properties with Residential Wells Fact Sheet and the Application for Rooftop Precipitation Collection System Permit (GWS-78) for more information.
  • Where can I collect the water from? From the roof of a building that is used primarily as a residence. 
  • How much water can I collect? There is no limit to the amount of water you can collect, so long as you are collecting the water from the roof of a building that is used primarily as your residence.
  • What can I collect the water in?  Rain barrels or other types of water storage structures.  Be sure to still follow best practices for mosquito management.
  • What can I use the water for?  Those residential uses that are allowed on the exempt well permit, which may include both indoor and outdoor uses, depending on the well permit.
  • Other important information:
    • If the residence is served by a water system (such as a water tap from a municipal provider or a shared well) that supplies more than three single family dwellings, then precipitation collection is not allowed under this law.
    • Please review the above information on SB09-080 before completing and submitting an Application for a Rooftop Precipitation Collection System Permit (GWS-78).  If your well has not been registered, you will also need to Register an Existing Well before applying.

 

Important Links

Informational Guides & Brochures

 

 

Storm Water Detention and Infiltration Facilities

Many storm water detention and infiltration facilities are exempted from surface water 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 groundwater is not exposed, and that new facilities are properly designed and noticed.  For more information on the notice process, see the Colorado Storm Water Detention and Infiltration Facilities Notification Portal in the links section below.  For any questions related to the use of the Notification Portal, please contact Mile High Flood District.  For more information on the statutory criteria please see DWR’s Administrative Statement on this topic.


Within Designated Basins storm water detention and infiltration facilities that meet specific criteria are administered as not causing material injury to vested water rights.  See Designated Basin Rules 2 CCR 410-1 below for those criteria and for notification requirements for new storm water detention and infiltration facilities.

 

Important Links