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Rainwater Collection & Storm Water Management 
DWR > Surface Water > Rainwater Collection & Storm Water Management

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.  In 2016, the 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.

DWR has developed a set of Regional Factors, as defined by House Bill 15-1016, to provide an estimate of pre-development consumptive use. If approved by the CWCB, these Factors can be used in a Substitute Water Supply Plan until a Pilot Project obtains an augmentation plan for permanent operation.  DWR presented the Regional Factors and supporting documents for public comment during July 2019.  Revised criteria and guidelines were adopted by the Colorado Water Conservation Board on September 18, 2019.

Regional Factors and Criteria and Guidelines Documents (Updated September 2019:

-September 2019 Revised Criteria and Guidelines
-Beginner's Guide to Rainwater Harvesting Pilot Projects and Regional Factors (pdf)
-Report on HB15-1016 Rainwater Harvesting Pilot Projects Regional Factors (pdf)
-Rainwater Harvesting Pilot Projects Legal Framework Memo
-Accounting template (Excel file)
-Rainwater Harvesting Pilot Projects Regional Factors for Accounting Presentation, July 2019 (pdf)

Rain Barrels and Residential Rooftop Precipitation Collection
Precipitation collection is allowed on residential properties under certain conditions.  In Colorado, water diversion and use is subject to administration under the prior appropriation doctrine in accordance with Colorado’s Constitution; however, legislation approved in 2016 and 2009 (described below) provide for limited situations where precipitation can be collected with some exception from strict administration in the water right priority system.  For a description of rainwater collection, water rights, and helpful information for homeowners in Colorado, see Colorado State University Extension's Rainwater Collection in Colorado Fact Sheet and Colorado Department of Public Health and Environment’s Residential Rain Barrels Best Practices Flyer.

Rain Barrels pursuant to House Bill 16-1005

House Bill 16-1005, effective August 10, 2016, allows precipitation to be collected from the rooftop 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? 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 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.  If your well has not been registered, you will also need to Register an Existing Well before applying.


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 any questions related to the use of the Notification Portal, please contact Urban Drainage and Flood Control District at (303) 455-6277.  For more information on the statutory criteria please see DWR’s Administrative Statement (2/11/2016).

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 below for additional details.




Have additional questions? Please call our Ground Water Information Desk between 9am and 4pm Monday through Friday at (303) 866-3587.