Summary of Colorado's Water Reuse Guideline or Regulation for Industry

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 industrial applications approved for use in Colorado
• Water reuse treatment category for industrial applications
• Additional context and definitions
• Water reuse for industrial applications 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, water reused for industry water reuse for industryThe use of recycled water for industrial applications, often created at the industrial facility. This includes recycled water generated through onsite processes such as boiler water, cooling water, manufacturing water, and oil and gas production, as well as recycled water generated offsite and imported elsewhere for industrial reuse applications. includes reuse for evaporative and non-evaporative industrial processes, non-discharging construction and road maintenance, washwater applications and oil and gas operations. The source of water (treated municipal wastewater) treated municipal wastewaterTreated 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 municipal wastewater. The write-up on this page 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 industry process water, including oil and gas produced water, for industrial reuse applications including evaporative and non-evaporative industrial processes, washwater applications, non-discharging construction and road maintenance, drilling and other uses approved with a permit. 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. Each category of reclaimed water has E. coli, turbidity and TSS specifications. Category 1 and Category 2 reclaimed water has 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, 2 and 3 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 industrial applications approved for use in Colorado

5 Code Colo. Regs. § 1002-84 defines the following approved industrial reuse applications of reclaimed water treated by centralized reclaimed water systems:

• Evaporative industrial processes (Categories 1, 2 and 3)
• Non-discharging construction and road maintenance (Categories 1, 2 and 3)
• Non-evaporative industrial processes (Categories 1, 2 and 3)
• Washwater applications (Categories 2 and 3)
• Oil and gas operations (Categories 2 and 3)

Water reuse treatment category for industrial applications

The various classes of treatment are defined by their respective treatment requirements and applicable performance standards. The respective treatment requirements are briefly summarized for industrial reuse applications:

• 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). For evaporative industrial processes, supplemental disinfection and disinfectant residual and/or public access restrictions are required if there is a significant likelihood for aerosols to drift to public or worker areas.
• 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 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).

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).

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. Users of reclaimed water must undergo education and training on how to use reclaimed water safely. Reclaimed water must be confined to use areas and precautions must be taken to ensure the water is not sprayed into non designated areas such as food preparation areas and drinking water facilities. Leaks must be repaired and point source discharges must be avoided and when they occur, must be reported in accordance with §25-8-601(2) CRS.

If there is a significant likelihood for aerosols produced during evaporative industrial processes to drift to public or worker areas, adequate signage and public access restrictions are required (5 Code Colo. Regs. § 1002-84).

Washing activities associated with washwater application must be contained (e.g., flow to lined pit or approved concrete washout area, or within enclosed equipment), to prevent any off-site runoff or discharge to ground water. Training must be provided on proper use and washing procedures when using reclaimed water (5 Code Colo. Regs. § 1002-84).

When recycled water is used for washwater application and non-discharging construction and road maintenance, application rates or other measures must be employed to minimize ponding or runoff from the area approved for application or use and prevent irrigation in excess of agronomic rate. For these industrial reuse applications as well as non-evaporative industrial processes, there may be a reasonable potential for worker or public exposure to aerosols generated in the use. Users of Category 1 Reclaimed Water or Category 2 Reclaimed Water must “employ measures to prevent the frequent exposure of workers and the public to aerosols generated in the use of reclaimed water. Measures shall include at least one of the following: minimum setback distance of 100 feet between the nearest source of aerosol generation and areas where workers or the public are normally present; physical barriers between aerosol sources and humans; personal protective equipment to prevent aerosol inhalation; functionally equivalent measures approved by a qualified individual (e.g., a certified industrial hygienist); or other means approved by the Division” (5 Code Colo. Regs. § 1002-84).

Reclaimed water can be used for oil and gas operations which is defined as exploring for oil and gas, including conducting seismic operations and the drilling of test bores; siting, drilling, deepening, recompleting, reworking or abandoning a well; producing operations related to any well, including installing flowlines; the generating, transporting, storing, treating or disposing exploration and production wastes; and any constructing, site preparing or reclaiming activities associated with such operations (COGCC, 2022).

Reclaimed water use for oil and gas operations is associated with environmental protections for transport of reclaimed water via layflat lines (commonly used to deliver water long distances), truck/vehicle tank hauling, leak detection and spill reporting requirements. Additionally, there are public notification requirements and water quality analysis requirements to protect workers and the public.

Water reuse for industrial applications specifications

Summary of Colorado's Water Reuse for Industrial Applications Reuse Specifications

Source= 5 Code Colo. Regs. § 1002-84, 2 Code Colo. Regs. § 404-1, 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 total suspended solids analysis.

Upcoming state law or policy

No upcoming regulations related to industrial water reuse were found for Colorado.

References:

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

Colorado Oil and Gas Conservation Commission. 2 CCR 404-1:907 (Management of Exploration & Production Waste). (a)(3), (c)(3), and (c)(E)(ii). (2015).

Colorado Department of Public Health and Environment Water Quality Control Commission (WQCC). 2020. WQCC Regulation No. 84 Reclaimed Water Control Regulation.

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 Oil and Gas Conservation Commission (COGCC). 2022. Rules and Regulations - Definitions - 100 Series.

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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.