Summary of Colorado’s Water Reuse Guidelines or Regulations for Consumption by Livestock, Landscaping and Onsite Non-potable Water Reuse

This page is part of the EPA’s REUSExplorer tool, which summarizes the different state level regulations or guidelines for water reuse for a variety of sources and end-uses.
The source water for this summary is Rainwater Collected Onsite.

On this page:

• Technical basis
• Onsite non-potable water reuse applications approved for use in Colorado
• Water reuse treatment category/type
• Additional context and definitions
• Onsite non-potable water reuse specifications (table)
• Upcoming state law or policy
• References
• Disclaimer

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This page is a summary of the state’s water reuse law or policy and is provided for informational purposes only. Please always refer to the state for the most accurate and updated information. 

In Colorado, consumption by livestock reuse applications include domestic animal watering and onsite non-potable water reuse applications include water closet and urinal flushing, fire protection systems and car washing. The source of water (rainwater collected onsite) rainwater collected onsite Precipitation collected at the district or regional scale is classified separately under 'stormwater.' is specified by the state as rainwater. The write-up uses state terms when discussing sources or uses of water that may differ from the Regulations and End-Use Specifications Explorer's (REUSExplorer's) terms.

Technical basis

Colorado approves the use of rainwater for onsite non-potable water reuse applications for outdoor purposes, including for car washing (HB16-1005) at most residential properties and for “ordinary household purposes,” fire protection, water consumed by livestock and domestic animals and/or landscape irrigation at residential properties that are supplied by an exempt or small capacity residential well (SB09-080). Rainwater must be used on the same property from which the rainwater was captured (HB16-1005). Rainwater may be collected from the roof of a residence by any system or method for use by the same dwellings that are or would be served by the well (SB09-080). All applicable provisions of the Clean Water Act (CWA) (33 U.S.C. §§ 1251 et seq.), including its implementing regulations, must be met in addition to any state water quality standards. Colorado does not provide specific requirements or specifications for the collection of rainwater for onsite non-potable water reuse applications (CDNR, 2023).

Residential properties of a single house or multi-family residences with four units or less are allowed to collect up to 110 gallons of rainwater at a time using a maximum of 2 rain barrels for outdoor onsite non-potable water reuse applications. No permit is required (HB16-1005; Colo. Rev. Stat. § 37-96.5-103).

Residential properties that are or are able to be supplied by an exempt or small capacity well can collect an unlimited amount of rainwater (roof collection only) for both indoor and outdoor permitted onsite non-potable uses (SB09-080). A Rooftop Collection System Permit is required for rainwater collection for residential properties with an exempt residential well permit or those that are legally entitled to an exempt residential well permit (Colo. Rev. Stat. § 37-92-602(1)(g)) or small capacity residential well permit (Colo. Rev. Stat. § 37-90-105(1)(f)).

Onsite non-potable water reuse applications approved for use in Colorado

HB16-1005 defines the following specific onsite non-potable water reuse applications for rainwater at residential properties that are not supplied by a residential well:

Outdoor purposes including irrigation of lawns and gardens (HB16-1005; Colo. Rev. Stat. § 37-96.5-103). Additional non-potable outdoor uses of rainwater collected in accordance with HB16-1005 are not specified. Indoor onsite use of rainwater at residential properties that are not supplied by a residential well is not permitted (HB16-1005).

SB09-080 defines the following specific onsite non-potable water reuse applications for rainwater at residential properties that are supplied or are able to be supplied by an exempt or small capacity residential well and are not served by a domestic water system that serves more than three single-family dwellings:

• “Ordinary household purposes” (e.g., toilet flushing, sanitary uses)
• Fire protection
• Water consumed by poultry, domestic animals and livestock on farms or ranches
• Irrigation of not more than 1 acre of gardens and lawns

The use of rainwater collected under SB09-080 is limited to use only for those purposes allowed by a well permit that has been or could be issued for the property (Colo. Rev. Stat. § 37-92-602(1)(g)(IV), § 37-90-105(1)(f)(III)). The use of rooftop rainwater collection systems in designated groundwater basins may be further limited by rules adopted by the board of a groundwater management district (Colo. Rev. Stat. § 37-90-105(7)).

Water reuse treatment category/type

Colorado does not assign harvested rainwater used for onsite non-potable water reuse to a category or class. Colorado does not require specific treatment requirements for harvesting rainwater, but does provide best practices to address concerns about mosquitos and water quality (CDNR, 2023).

Additional context and definitions

To address concerns about mosquitos, Colorado requires rain barrels to be equipped with a sealable lid and for the rain barrel to be emptied at least once a month (HB 16-1005; CSU Extension, 2016). To address absorption of impurities (e.g., heavy metals, bird droppings, dust) from the atmosphere and roofing materials, it is recommended to use first flush diverters to filter and screen out contaminants before they enter the storage container (CSU Extension, 2016). Roof washing is not needed for water used solely for irrigation purposes (CSU Extension, 2016).

Colorado does not allow homeowner associations to ban the use of rain barrels. Colorado does allow reasonable aesthetic requirements on location and appearance of rain barrels (CSU Extension, 2016).

Onsite non-potable water reuse specifications

None.

Upcoming state law or policy

No upcoming onsite non-potable water reuse regulations related to rainwater were found for Colorado.

References:

Clean Water Act, 33 U.S.C. §§ 1251 et seq.

Colorado Department of Natural Resources (CDNR). 2023. Rainwater, Storm Water & Graywater.

Colorado State University (CSU) Extension. 2016. Rainwater Collection in Colorado.

Residential Precipitation Collection, HB16-1005.

Rooftop Precipitation - Definitions, Colo. Rev. Stat. § 37-96.5-102 (2016).

SB09-080. 2009.

Small-capacity rooftop precipitation collection permitted, Colo. Rev. Stat. § 37-96.5-103.

Water Right Determination and Administration Part 6 – Application of Article. exemptions – legislative declaration – definitions, Colo. Rev. Stat. § 37-92-602(1)(g).

Underground Water. Small capacity wells, Colo. Rev. Stat. § 37-90-105(1)(f)(III).

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Disclaimers

Please contact us at waterreuse@epa.gov if the information on this page needs updating or if this state is updating or planning to update its laws and policies and we have not included that information on the news page.