5 Colo. Code Regs. § 1002-86.23
The provisions of sections 25-8-202(1)(c) and 25-8-205(1)(g), C.R.S., provide the specific statutory authority for the Graywater Control Regulation adopted by the Water Quality Control Commission (commission). The commission has also adopted, in compliance with section 24-4-103(4), C.R.S., the following statement of basis, specific statutory authority, and purpose.
BASIS AND PURPOSE
Upon adoption of Regulation No. 86 in 2015, the commission anticipated future reviews to consider improved organization and readability, whether to allow additional uses and treatment works of graywater and whether to adopt a variance process. During the triennial review hearing in 2021, the commission directed the division to conduct a stakeholder process to discuss these topics in addition to other proposed items from the division. As a result, the commission adopted several changes to this regulation during the rulemaking on November 13, 2023.
The commission added language in the Applicability section to clarify circumstances for graywater treatment works that have been approved prior to this regulatory revision ((86.6(A)(3)). The language states that if graywater treatment works were approved prior to revisions to Regulation No. 86, the treatment works remain in compliance until modifications are made, or a public or environmental health risk is identified. The commission deemed this a safe and appropriate means to avoid abrupt, burdensome costs associated with continuous upgrades or alterations as this regulation is updated. The commission's intent was to allow existing systems to persist as long as they are safe for public health and the environment.
The commission deemed it necessary to include a requirement for local graywater control programs to require compliance with nutrient control regulations (5 CCR 1002-71 through 1002-75), and for notification to be provided to the basin control authorities. Regulation No. 86 does not contain phosphorus treatment techniques or standards.
The commission clarified the timeline for local agencies to update and ensure compliance of their local ordinance or resolution within 365 days from the effective date of the most recent regulation adopted by the commission. If the division determines that a local ordinance or resolution is out of compliance with Regulation No. 86, the ordinance or resolution must be revised within 180 days of written notice by the division to the local authority.
The definition of "Backflow Device" was deleted, and definitions for "Backflow Contamination Event," "Backflow Prevention Assembly" and "Backflow Prevention Method" were added to be consistent with terminology used in Colorado's Primary Drinking Water Regulation No. 11. Definitions of "ENERGY STAR" and "Integrated Water Factor" were added because these terms and data are used to calculate flow projections for laundry machines in section 86.11. A definition of "Laundry to Landscape" was added because the commission adopted this type of graywater treatment works in this regulation. In sections 86.11(A)(1)(ii)(a) and (b), the commission decided to switch the terminology from "traditional fixtures" and "water saving fixtures" to "Non-WaterSense fixtures" and "WaterSense fixtures," respectively, because the former terms do not have definitions in the 2012 Uniform Plumbing Code. Therefore, a definition of "WaterSense" was added. WaterSense is the Environmental Protection Agency's (EPA's) program for testing and labeling water efficient fixtures. It is also the intent that if the WaterSense program was replaced with another water efficiency program, the definition would still apply.
The commission added category A1: Laundry to Landscape graywater treatment works for single family users to employ subsurface irrigation, including mulch basins. A definition, design criteria and control measures were added. The commission found that single family units that allow for short term rental agreements (e.g. Airbnb, VRBO, etc.) should be prohibited from using Laundry to Landscape systems. The graywater effluent should be consistently produced from a permanent source to prevent the risk of potential outbreaks. Short term renters may not be aware of the control measures and other requirements in place to maintain safe Laundry to Landscape systems, and graywater effluent from multiple persons from various regions would resemble multifamily effluent that poses a greater public health risk.
The commission added an allowance of edible crop irrigation for subsurface irrigation for single family users (includes irrigation from Laundry to Landscape systems). Irrigation of sprouts, leafy greens and root crops is prohibited. The commission's main concern was ingestion of pathogens, and research has shown that non-spray irrigation methods on crops that grow above ground is a low risk and efficient use of graywater. Additionally, a control measure was added that edible crops irrigated with graywater treatment works must be washed with potable water prior to consumption. The commission determined that edible crop irrigation should be prohibited for non-single family users and single family units that allow for short term rentals (e.g. Airbnb, VRBO, etc.) because of the higher risk associated with pathogens in non-single family graywater effluent. As with Laundry to Landscape systems, the commission believed graywater effluent should be consistently produced from a permanent source to prevent the risk of potential outbreaks.
The commission added rural fire protection as graywater use categories D1 and D2 to provide options for jurisdictions that allow fire sprinkler systems in homes of specific sizes located in remote areas that do not have readily available storage tanks, fire hydrants or other water supplies for firefighting. While there are risks associated with using graywater for firefighting, the commission determined that protection of life from fire is a greater priority at the time of an emergency. The commission required the local city, city and county, or county to obtain agreement from the local fire district/authority prior to adopting this use in their local ordinance or resolution. It was determined that the design criteria and modified control measures for toilet and urinal flushing be used for rural fire protection to be protective of human health. Graywater must be stored in an outdoor, watertight cistern with signage to notify firefighters that graywater is contained in the cistern.
The commission adopted a new labeling series for the graywater use categories shown in the table below.
Category | Use | Graywater Source(s) | End Use |
A1 | Laundry to Landscape | Laundry Machines | Outdoor mulch basins (single family dwelling) |
B1 | Single family subsurface irrigation (landscapes) | All allowed graywater sources | Outdoor subsurface irrigation and mulch basins (single family dwelling) |
B2 | Non-single family subsurface irrigation (landscapes) | All allowed graywater sources | Outdoor subsurface irrigation and mulch basins (non-single family) |
C1 | Single family indoor toilet and urinal flushing | All allowed graywater sources | Indoor toilet and urinal flushing (single family dwelling) |
C2 | Non-single family indoor toilet and urinal flushing | All allowed graywater sources | Indoor toilet and urinal flushing ( non-single family) |
D1 | Single family rural fire protection | All allowed graywater sources | Indoor/outdoor firefighting, storage tank outdoor (single family dwelling) |
D2 | Non-single family rural fire protection | All allowed graywater sources | Indoor/outdoor firefighting, storage tank outdoor (non-single family) |
The commission decided to use the EPA's ENERGY STAR, Integrated Water Factor (IWF) for ENERGY STAR rated laundry machines. ENERGY STAR is an EPA label that is certified to meet strict standards for energy efficiency and incorporates water savings calculations into their product certifications. The IWF is a measure of water efficiency that considers gallons of water consumed per cubic foot of capacity. The IWF's can be found on EPA's website, and with the product information for ENERGY STAR laundry machines. For laundry machines that do not have an ENERGY STAR label, the flow projections previously used in Regulation No. 86 will apply. The flow rate for traditional fixtures (laundry machines that are not ENERGY STAR rated) was reduced from 15 gallons per day per occupant (gpd/occupant) to 10 gpd/occupant based on more recent and reliable laundry machine water usage data.
The commission developed a new equation to be used to calculate landscaped area for Laundry to Landscape systems and mulch basins. The commission deleted the previous equation from Regulation No. 86 because the new equation is a simplified version that reaches the same end goal. Soil type and loading rate are uniform and reliable factors to consider whether there is sufficient graywater volume absorption for graywater subsurface irrigation.
The commission developed a new and separate equation for sizing landscaped areas for single and non-single family dispersed subsurface irrigation systems (Graywater Use Categories: B1 and B2). Table 12-2 used for Laundry to Landscape systems is appropriate for non-pressurized irrigation systems. Dispersed subsurface irrigation systems that are not installed in mulch basins are pressurized. Table 12-3 in section 86.12(B)(3)(b)(i) is specific for pressurized irrigation systems and will result in more accurate landscaped area calculations for these types of systems.
Additionally, the commission changed the minimum depth of subsurface irrigation components from four inches to two inches (sections 86.8(45) and 86.12(B)(1)(a)). Two inches is in line with the recommendation in the 2024 Uniform Plumbing Code.
The commission removed the requirement that a certified operator under the Water and Wastewater Facility Operators Certification Board be required for non-single family Graywater Treatment Works with a design capacity of 2,000 gpd or less. Most NSF 350 treatment works are relatively simple, and a designated responsible person who can operate and maintain the treatment works according to the conditions in 86.16(A) will be protective of public health. Non-single family graywater treatment works with a design capacity of greater than 2,000 gpd will continue to be required to be operated by a certified operator per Regulation No. 100.
5 CCR 1002-86.23