Summary of Colorado's Water Reuse Guideline or Regulation for Landscaping
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 Treated Municipal Wastewater.
On this page:
- Technical basis
- Water reuse for landscaping approved for use in Colorado
- Water reuse treatment category for landscaping
- Additional context and definitions
- Water reuse for landscaping specifications (table)
- Upcoming state law or policy
- References
- Disclaimer
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, water reuse for water reuse for landscapingThe use of recycled water on land to assist in the irrigation of vegetation in residential and non-residential areas. Includes impoundments to store water for irrigation , ornamental vegetation, parks, school yards, sporting facilities (including golf courses), private gardens, roadsides and greenbelts, and cemeteries. Excludes irrigation of areas used for agriculture, commercial reuse applications, or any centralized non-potable reuse. includes landscape irrigation in areas with unrestricted and restricted access and resident controlled landscape irrigation. The source of water treated municipal wastewater Treated wastewater effluent discharged from a centralized wastewater treatment plant of any size. Other terms referring to this source of water include domestic wastewater, treated wastewater effluent, reclaimed water, and treated sewage. is specified by the state as domestic wastewater. This 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 reclaimed water for landscape irrigation in areas with both restricted access and unrestricted access (5 Code Colo. Regs. § 1002-84). All applicable provisions of the Clean Water Act (CWA) (33 U.S.C. §§ 1251 et seq.). Treatment requirements and performance standards are applied for the removal of microbial contaminants, chemicals and other relevant indicators for water reuse for landscaping and are summarized in the table. Reclaimed water (Categories 1 and 2) have E. coli specifications based on the EPA’s 1986 Ambient Water Quality Criteria (AWQC). The decision to use the 1986 AWQC was made in 2000, prior to EPA’s 2012 updates. While the approved Category 1 and 2 uses do not directly correlate to swimming, the Water Quality Control Commission assumed criteria established to protect swimmers will be more protective than individuals “casually exposed” to reclaimed domestic wastewater (5 Code Colo. Regs. § 1002-84). Turbidity is also used as a surrogate measure of “microbial purity” (in regard to viruses and parasites) in reclaimed domestic wastewater. A “middle ground” of 5 NTU (in more than 5% of results per month) was selected for the application of reclaimed domestic wastewater (5 Code Colo. Regs. § 1002-84).
Water reuse for landscaping approved for use in Colorado
5 Code Colo. Regs. § 1002-84 defines the following approved water reuse for landscaping of reclaimed water treated by centralized reclaimed water systems for:
- Landscape irrigation in areas with restricted access only (Category 1)
- Landscape irrigation in areas with unrestricted and restricted access (Category 2)
- Resident controlled landscape irrigation (Category 3)
Treatment standards for water reuse for landscaping are the same for both centralized municipal and onsite water sources in Colorado. The same information is housed in the onsite non-potable reuse webpage for reclaimed water treated by localized systems whereas this webpage focuses on use of recycled water from centralized systems.
Water reuse treatment category for landscaping
The various classes of treatment are defined by their respective treatment requirements and applicable performance standards.
- For Category 3 reclaimed water, the treatment requirements are secondary treatment with filtration and disinfection. Category 3 water has an E. coli requirement of zero detections in the last 75% of samples (each calendar month) and ≤126 E. coli/100 mL (single sample maximum).
- For Category 2 reclaimed water, the treatment requirements are secondary treatment with filtration and disinfection. Category 2 water has an E. coli requirement of ≤126 E. coli/100 mL (monthly geometric mean) and ≤235 E. coli/100 mL (single sample maximum).
- For Category 1 reclaimed water, the treatment requirements are secondary treatment with disinfection. Category 1 water has an E. coli requirement of ≤126 E. coli/100 mL (monthly geometric mean) and ≤235 E. coli/100 mL (single sample maximum).
Additional context and definitions
In Colorado, reclaimed water is defined as “domestic wastewater that has received secondary treatment by a domestic treatment works (centralized or localized system) and such additional treatment as to enable the wastewater to meet the standards for approved uses” (Colorado WQCC 2007). This summary focuses on domestic wastewater treated by centralized systems; the domestic wastewater treated by localized (on-site) systems is discussed in a separate EPA summary for onsite non-potable reuse applications.
Domestic reclaimed water users must notify the public via sufficiently sized signs in all use areas, tanks and other equipment used for storage or distribution of reclaimed domestic wastewater that warn that reclaimed water is being used and is not safe for drinking (5 Code Colo. Regs. § 1002-84). All new or replaced piping, valves, outlets and other appurtenances must be marked to differentiate reclaimed water from potable water or other piping systems. An approved cross connection control device or method must be provided at all potable water service connections to reclaimed water use areas. Irrigation equipment that is used with reclaimed water cannot be hooked up to potable spigots.
Water reuse for landscaping specifications
Summary of Colorado's Water Reuse for Landscaping Specifications
| Recycled Water Class/Category | Source Water Type | Water Quality Parameter | Specification | Sampling/Monitoring Requirements (Frequency of monitoring; site/ location of sample; quantification methods)* |
|---|---|---|---|---|
|
Category 3 (Resident controlled landscape irrigation) |
Domestic wastewater |
E. coli |
0 detected in at least 75% of samples (per calendar month) ≤126 E. coli/100 mL (single sample maximum) |
4 grab samples per 7 days |
|
Turbidity |
≤3 NTU (monthly average) 5 NTU (cannot exceed in more than 5% of results per month) |
1 reading per 12 hours of operation |
||
|
Total dissolved solids |
mg/L (specific value not required) |
Monitored by treaters on a quarterly basis with results submitted to the Colorado Water Quality Control Division through Discharge Monitoring Reports and to all food crop irrigation users. Results can be provided within a larger report (like a Consumer Confidence Report). |
||
|
Nickel |
Not specified |
If requested by a user, treaters must provide to its users monitoring data that is less than 12 months old within 60 days of the request. Monitoring should take place at the point of compliance. |
||
|
Arsenic |
||||
|
Lead |
||||
|
Cadmium |
||||
|
Mercury |
||||
|
Nitrogen |
Irrigation with reclaimed water must occur at or below the agronomic rate for nitrogen (Colorado WQCD 2007) |
Not specified |
||
|
Phosphorus |
Some basins in CO have phosphorus limits. If reclaimed water is used to irrigate in those basins, the phosphorus limits must be considered. |
Not specified |
||
|
Category 2 (Landscape irrigation in areas with unrestricted and restricted access) |
Domestic wastewater |
E. coli |
<126 E. coli/100 mL (monthly geometric mean) ≤235 E. coli/100 mL (single sample maximum) |
2 samples per 7 days, grab |
|
Turbidity |
≤3 NTU (monthly average) 5 NTU (cannot exceed in more than 5% of results per month) |
1 reading per 12 hours of operation |
||
|
Nickel |
Not specified |
If requested by a user, treaters must provide to its users monitoring data that is less than 12 months old within 60 days of the request. Monitoring should take place at the point of compliance. |
||
|
Arsenic |
||||
|
Lead |
||||
|
Cadmium |
||||
|
Mercury |
||||
|
Nitrogen |
Irrigation with reclaimed water must occur at or below the agronomic rate for nitrogen (Colorado WQCD 2007) |
Not specified |
||
|
Phosphorus |
Some basins in CO have phosphorus limits. If reclaimed water is used to irrigate in those basins, the phosphorus limits must be considered. |
Not specified |
||
|
Category 1 (Landscape irrigation in areas with restricted access only) |
Domestic wastewater |
E. coli |
<126 E. coli/100mL (monthly geometric mean) ≤235 E. coli/100 mL (single sample maximum) |
1 sample per 7 days, graba |
|
Total suspended solids (TSS) |
30 mg/L (daily maximum) |
|||
|
Nickel |
Not specified |
If requested by a user, treaters must provide to its users monitoring data that is less than 12 months old within 60 days of the request. Monitoring should take place at the point of compliance. |
||
|
Arsenic |
||||
|
Lead |
||||
|
Cadmium |
||||
|
Mercury |
||||
|
Nitrogen |
Irrigation with reclaimed water must occur at or below the agronomic rate for nitrogen (Colorado WQCD 2007) |
Not specified |
||
|
Phosphorus |
Some basins in CO have phosphorus limits. If reclaimed water is used to irrigate in those basins, the phosphorus limits must be considered. |
Not specified |
Source= 5 Code Colo. Regs. § 1002-84; Colorado WQCC 2007
* Information about sampling and monitoring requirements such as frequency, site and quantification methods not specifically listed in the table was not explicitly specified in the State-specific regulations.
a Grab or composite samples may be used for TSS.
Upcoming state law or policy
No upcoming regulations pertaining to water reuse for landscaping were found for Colorado.
References
Clean Water Act, 33 U.S.C. §§ 1251 et seq.
Colorado Department of Public Health and Environment Water Quality Control Commission (WQCC). 2007. WQCC Water Quality Policy (WQP) - 25 Monitoring and Reporting Requirements for Reclaimed Water Treatment Facilities.
Colorado Water Quality Control Division (WQCD). 2007. Water Quality Permits – Guidelines for the Determination of Agronomic Rate for Application of Reclaimed Water Under Colorado Regulation No. 84.
Reclaimed Water Control Regulation, 5 Code Colo. Regs. § 1002-84.
Schoen ME, Ashbolt NJ, Jahne MA, Garland J. Risk-based enteric pathogen reduction targets for non-potable and direct potable use of roof runoff, stormwater, and greywater. Microb Risk Anal. 2017;5:32-43. doi: 10.1016/j.mran.2017.01.002
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.