5 Colo. Code Regs. § 1002-86.21
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 24-4-203(4), C.R.S., the following statement of basis, specific statutory authority, and purpose.
BASIS AND PURPOSE
The commission has determined that the adoption of the requirements set forth in Regulation #86 are necessary to protect public health and the environment in the state. The commission believes that the implementation of graywater use in Colorado will proceed more expeditiously by limiting the initial regulatory scope. This approach promotes development of local graywater programs through two initial graywater uses with specific treatment and control measure requirements. The commission expects the adoption of modifications to Regulation #86 over time to allow for additional graywater uses, graywater users, and expanded treatment options. The commission anticipates future reviews of this regulation to include a review for improved organization and readability, and also anticipates that the next review will consider whether to allow agricultural irrigation as a use, and whether to adopt variance provisions.
It is the intent of the commission that this regulation promote the use of graywater by providing a comprehensive framework which, when followed, will assure responsible use of graywater compatible with the state's public policy to foster the health, welfare and safety of the inhabitants of the state of Colorado and to protect, maintain, and improve, where necessary and reasonable, the water quality in Colorado.
House Bill 13-1044 was signed into law on May 15, 2013, and authorizes the use of graywater in Colorado. The legislation defined "graywater" and "graywater treatment works" and established a basic implementation framework for graywater use within Colorado.
Under the statute, each local city, city and county, or county are able to decide whether to allow graywater use within its jurisdiction via the adoption of a resolution or ordinance that meets minimum local, state and federal requirements, including but not limited to the Colorado Plumbing Board regulations, local graywater control programs, water rights requirements, and operator certification requirements. All graywater users must wait until all relevant regulations are effective before implementing graywater treatment works.
Through adoption of this regulation, the commission is encouraging the use of graywater. Because graywater has the potential to be a human pathogen pathway, the commission is adopting measures to adequately protect public health. The graywater regulation is structured so that local governments will have flexibility to adopt ordinances, resolutions, and rules that are appropriate in each individual circumstance. Local graywater control programs are voluntary, and may allow one or both of the authorized graywater uses. The local graywater control program may be more stringent but must meet the minimum requirements of Regulation #86. Since neither the local implementing agencies nor the state agencies were allocated funds for graywater regulation, ordinance, code, resolution, and other supporting graywater control legal framework, the regulation aims to be cognizant of resource limitations linked to local implementation. At this time, the commission is authorizing two graywater uses - indoor toilet flushing and outdoor subsurface irrigation. The commission anticipates that the allowed graywater uses may be expanded in the future after Colorado gains some experience and further scientifically based research can define the risks and benefits.
The statute states that, "graywater may only be used in areas where the local city, city and county, or county has adopted an ordinance or resolution approving the use of graywater", and ordinances and resolutions must be "in compliance" with the commission's regulation and other federal, state, and local. §§ 25-8-205(1)(g)(II), 31-11-107(1) and 31-15-601(1)(m), C.R.S.
The Commission declined to grandfather preexisting graywater systems. All graywater systems in Colorado must meet the requirements of this regulation.
There are some on-site waste water treatment systems ("OWTS") that, in addition to disposal, use some of the water generated from these systems for subsurface irrigation. The purpose of these systems is sewage disposal. These systems were approved prior to May 15, 2013, pursuant to Regulation #43: On-Site Wastewater Treatment System Regulation ("OWTS") (5 CCR 1002-43.4 or Individual Sewage Disposal System Guidelines ("ISDS") (5 CCR 1003-6.IV.J) which allows a local public health agency to approve "experimental" OWTS or ISDS systems. The record indicated there are a small number of these systems, less than 10. The Commission adopted section 86.6(A)(2) to address these systems. These systems will continue to operate under Regulation No. 43 and will be deemed in compliance with this regulation unless and until modifications are made, at which time the system will need to evaluate its system and to the extent applicable must come into compliance with requirements of this regulation.
A local city, city and county or county that adopts a graywater ordinance or resolution must include the ability to compel graywater users to discontinue the practice in the event the program is discontinued. Where a local jurisdiction adopts a local graywater program, and later decides to discontinue the local graywater control program, the local government may either fully discontinue the program or adopt a limited graywater control program to allow existing graywater systems to continue. The "limited graywater control program" option means that the previously adopted local control program (including all Regulation #86 requirements) can be limited to the existing graywater treatment works and that no additional applications for graywater systems will be accepted.
The statute conveys exclusive enforcement authority regarding compliance with the local ordinance or resolution to the local jurisdiction. The commission does not intend to directly enforce on individual users or graywater treatment works that are located within a local graywater control program. In cases where there is no local graywater control program in place, graywater use within the local jurisdiction will not be authorized and the user (not the local agency) may face enforcement action from the Water Quality Control Division (division).
A local city, city and county, or county that chooses to adopt a local graywater control program must notify the Division within 60 days of adoption and provide a copy of the ordinance, or resolution and, if applicable, rule. The division may review the ordinance or resolution to ensure that the ordinance or resolution meets the minimum intent of Regulation #86, and may take action to compel any local graywater program to conform to the minimum requirements of the regulation.
The commission relied upon existing regulatory definitions where possible and adopted definitions for several terms not already defined in statute. The definitions of the terms "cross-connection" and "public water system" were taken from Regulation #11: Colorado Primary Drinking Water Regulations. The definitions of the terms "component", "design", "design flow", "floodplain", "floodway", "local public health agency", "on-site wastewater treatment system", "percolation test", "site evaluation", "soil horizon", "soil profile test pit", and "soil structure" were taken or modified from Regulation #43: On-site Wastewater Treatment System Regulation. The definitions of the terms "agronomic rate", "agricultural irrigation", and "Division" were taken or modified from Regulation #84: Reclaimed Water Control Regulation. The definition for "indirect connection" was modified from the International Plumbing Code 2012 edition definition of an "indirect waste pipe". The definitions of the terms "suitable soil" and "subsurface irrigation" were modified from Washington Administrative Code Chapter 246-274.
The commission created definitions for "closed sewerage system", "facility", "legally responsible party", "local agency", "local graywater control program", "modification", "public nuisance", and "single family".
In section 86.9 of the regulation, the commission set mandatory minimum requirements for a resolution or ordinance and, if applicable, rule as adopted by a local agency. The minimum requirements are intended to ensure that the local graywater control program meets the statutory requirements and to ensure a comprehensive graywater program. Based on stakeholder feedback, the regulation allows some administration elements to be authorized in rule, rather than in ordinance or resolution. The minimum requirements are meant to be flexible recognizing that many local agencies will incorporate graywater into existing business processes. A local agency may adopt more stringent standards in its ordinance, resolution, or rule.
A local government may only authorize graywater use in accordance with federal, state, and local requirements. The city, city and county, or county is ultimately responsible for legal compliance with its own ordinance or resolution. Before a local city, city and county, or county adopts an ordinance or resolution to authorize the use of graywater, a board of county commissioners or a municipal governing body is encouraged to coordinate with other local agencies, including but not limited to, the local board of health, local public health agencies, any water and wastewater service providers, and basin water quality authorities. Coordination with other local agencies may be accomplished through memorandums of agreement, memorandums of understanding, agency referral mechanism, or agency agreements. The commission anticipates there may be circumstances where one regulatory entity's rules and regulations could impact the legality of graywater use in a portion of an overall jurisdiction. For example, if a county allows graywater use but a portion of the county is served by a public water system that does not have appropriate water rights to allow graywater uses, this portion of the county must be excluded from the local graywater control program.
The ordinance, resolution, or rule must clearly state the requirements for graywater use within the jurisdiction. The local graywater control program must outline: the allowed graywater category(ies), the graywater treatment design criteria, site and soil evaluation methodology (if applicable), any regulatory fees, any testing requirements, or specific local requirements. The regulation does not require that an ordinance impose fees or water quality reporting.
A local agency's graywater program must include a tracking mechanism for all graywater treatment works, a regulatory approval process, and mechanisms to ensure that on-going graywater use is done in compliance with the requirements of the resolution, ordinance, or rule (e.g., control measures are being met). The commission concludes that a local graywater program must address all graywater treatment works within a jurisdiction, including single family users. Current information on the installed graywater treatment works will be useful in the event of an outbreak investigation and during property transfers. Information regarding the legally responsible party associated with every graywater treatment works will also allow the local jurisdiction to have a contact for the decision maker of each graywater treatment works.
The commission determined that the ordinance or resolution must define the local regulatory structure to implement the program to ensure compliance with the resolution or ordinance. The ordinance or resolution must clearly state which agency(ies) are involved in a local graywater control program and each agency's roles and responsibilities. These requirements are meant to encourage coordination within and between agencies.
Since the local jurisdiction will have enforcement authority, the local graywater control program must include violation notification mechanisms and escalation or enforcement actions. Possible violations of the ordinance or resolution that cause enforcement actions include, but are not limited to: not testing backflow prevention devices as required, not complying with control measures, and installation of a new or modification of an existing system without going through an approval process.
The local jurisdiction will be responsible for coordinating with the Water and Wastewater Facility Operator Board to ensure that any Regulation #100: Water and Wastewater Facility Operator Certification Requirements are being satisfied. The commission encourages local jurisdictions to incorporate a mechanism for operator compliance assurance and a referral mechanism to the Water and Wastewater Facility Operator Board.
The commission is authorizing two uses for graywater - subsurface irrigation and indoor toilet /urinal flushing. There were several factors that guided the commission in determining the graywater categories within the two allowed graywater uses, including the population exposed, potential health exposure, potential cross-connection control risk, and environmental risk. The commission established a major category distinction between a single family residential user and all other users (referred to in the regulation as non-single family). The commission anticipates that a single family user will be financially and personally vested in keeping the household graywater treatment works operating properly. Single family residents will likely be aware of the health status of the other residents in their immediate household. In contrast, non-single family users may not be as diligent in following graywater control measures, may not understand the implications to other graywater users, or may not be responsible for maintaining a graywater treatment works. Accordingly, four graywater use categories were created to address single family and non-single family graywater use for subsurface irrigation (Categories A and B) and indoor toilet and urinal flushing (Categories C and D).
Within the four graywater categories, the commission is adopting daily graywater flow restrictions to ensure that graywater treatment works are consistent with other commission regulations. The commission decided to define a daily graywater flow rate rather than use the building occupancy for a variety of reasons. A daily flow rate is more consistent with the plumbing code, and is more consistent with other commission regulations. Based on a joint American Water Works Association Research Foundation (AwwaRF) and American Water Works Association (AWWA) study titled the Residential End Uses of Water, approximately 30 to 35 gallons per day (gpd) of graywater is produced per person and approximately 18.5 gpd/person is used for toilet flushing. The commission decided on a flow limit of 400 gpd for single family users which is roughly the amount of graywater produced by 10 people and the amount that 22 people could use for indoor toilet flushing. The non-single family limit of 2,000 gpd is roughly the amount of graywater produced by 50 people and the amount that 108 people could use for indoor toilet flushing.
Graywater is expected to contain nitrogen, phosphorus, and total dissolved solids which are regulated pollutants for groundwater discharges under Regulation #41 (5 CCR 1002-41). The commission determined that the potential risks to groundwater from graywater systems are similar to the risk posed by decentralized onsite wastewater treatment systems. Therefore, at the same time as adopting this control regulation, the commission revised Regulation #61 (section 61.14(1)(b)) to exempt graywater treatment works from the requirement to obtain a discharge permit.
In addition to design requirements, the commission is adopting control measures, which are the required routine actions for graywater treatment works. The control measures compliment the design criteria. The control measures attempt to control potential graywater exposure though: limitation of graywater contamination at the point of production (e.g., sink), proper operation of the treatment process, and limitation of graywater exposure (e.g., toilet or irrigation system). For example, the design criteria for indoor toilet flushing use requires the installation of a dye injection system and the associated control measure is the daily operation of the dye injection system. The control measures are the critical barrier to protect public health and environment after installation of the graywater treatment works. The adopted control measures were developed after reviewing other states' graywater programs and the International Plumbing Code requirements. Some control measures are required for all graywater uses, while other control measures are only required for subsurface irrigation or indoor toilet flushing.
* Graywater must be collected in a manner that minimizes the presence or introduction of hazardous or toxic chemicals to the greatest extent possible. Residual hazardous or toxic chemicals may result from activities including, but not limited to: the use of cleaning chemicals; the use of hazardous household products; waste from a water softener; cleaning car parts; washing greasy or oily rags or clothing; rinsing paint brushes; disposal of pesticides, herbicides, or other chemicals; disposing of waste solutions from home photo labs or similar hobbyist or home occupation activities; or from other home maintenance activities.
* Graywater must be collected in a manner that minimizes the presence or introduction of human excreta to the greatest extent possible. Human excreta may result from activities such as, but not limited to: washing diapers, washing soiled garments, and washing infectious garments.
* Graywater must be collected in a manner that minimizes the presence or introduction of household wastes. Residual household wastes may result from activities including, but not limited to: the use of cleaning chemicals; pharmaceuticals, or from home maintenance activities.
* Graywater must be collected in a manner that minimizes the presence or introduction of animal or vegetable matter. Animal or vegetable matter may result from activities such as but not limited to: cooking, cleaning, and washing pets
* Use of graywater is limited to the confines of the facility that generates the graywater. This control measure is a statutory requirement.
* The graywater treatment works must be operated and maintained in accordance with the O&M manual, including all manufacturer recommended maintenance activities. On the surface this control measure is similar to the administration section which requires each graywater treatment works to have an O&M manual. However, this control measure requires that the O&M manual be actively followed and be used to guide proper operation and maintenance of a graywater treatment works. The commission included a five (5) year minimum O&M recordkeeping requirement for Category D graywater treatment works that have a capacity to receive equal to or greater than 2,000 gallons per day since maintenance of these systems will be essential to protect public health. In the event of an outbreak, having records will allow public health officials to have a baseline of operational information to ensure that the graywater treatment works was properly operated.
* The owner or operator of a graywater treatment works must minimize exposure of graywater to humans and domestic pets. Research indicates that graywater is to be expected to contain human pathogens. Therefore, the commission considers minimization of exposure to humans and pets as a common sense measure to limit possible pathogen pathways. The commission understands that some exposures will be necessary for graywater treatment works maintenance, cleaning, aerosolization when flushing of urinals and toilets, and irrigation system maintence. Users should be aware that human pathogens are likely present, and should therefore limit their exposure as much as possible and take protective measures.
* Graywater use and graywater treatment works must not create a public nuisance. Graywater use and graywater treatment works must not create public nuisances such as odors and disease vectors (e.g., mosquitoes) habitat.
* Graywater must not be stored for more than 24 hours unless the graywater has been treated by a graywater treatment works that meets the design requirements of section 86.12. All graywater must be stored inside a tank(s) that meets the design requirements of section 86.12. Graywater stored for an extended time period will create an environment that encourages microorganism growth. Extended storage of untreated graywater will result in anaerobic (a.k.a. no oxygen) conditions and unpleasant odors. Colorado water rights laws will likely impact storage of treated graywater for an extended time period. In addition, this requirement is in conformance with the 2015 International Plumbing Code.
* Temporary or semi-temporary connections from the potable water system or public water system to the graywater treatment works are prohibited. Permanent connections from the potable water system or public water system must be controlled with an appropriate backflow prevention assembly or backflow prevention method. Temporary potable water connections to graywater treatment works are not allowed. An example of a temporary connection is a hose submerged in a graywater storage tank to provide irrigation water during vacation. The prohibition was put in place since temporary connections will not undergo design approval or have an appropriate backflow prevention assembly or backflow prevention method. While temporary connections are prohibited, graywater treatment works may have a permanent connection from a potable water system or public water system. Permanent connections from the potable water system or public water system must be controlled with an appropriate backflow prevention assembly or backflow prevention method as required in section 86.12.
* Agricultural irrigation with graywater is prohibited. In order to be protective of public health, and because insufficient information was presented at this hearing to fully evaluate the risk to public health, graywater may not be used for agricultural irrigation. The definition of agricultural irrigation includes household gardens, fruit trees, and other flora intended for human consumption. This is especially critical for local jurisdictions that allow household produced food products to be sold at farmers markets. The commission considers "human consumption" to mean any food or beverage consumed by humans, regardless of the processing method (e.g., raw, fermented, baked, canned).
* Irrigation is prohibited when the ground is frozen, plants are dormant, during rainfall events, or the ground is saturated. The commission intends to ensure that graywater use does not result in ponding, runoff, or unauthorized discharge to state waters. Therefore, graywater irrigation under these conditions is not allowed.
* Irrigation scheduling must be adjusted so that application rates are closely matched with soil and weather conditions. The amount of water needed for irrigation is dependent on a variety of local conditions such as the flora being irrigated, weather condition, and local soils. The user needs to be mindful that the required amount of graywater and nutrients will change over time and therefore the graywater application rate must also be adjusted.
* Graywater must be applied at an agronomic rate which does not result in ponding, runoff, or unauthorized discharge to state waters. The definition of agronomic rate is generally consistent with the definition from Regulation #84 (which addresses centralized reclaimed water operations). While this regulation does not require a water quality test, such testing is encouraged. Graywater use must not result in ponding, runoff, or unauthorized discharge to state waters.
* For mulch basin systems, mulch must be replenished as required due to decomposition of organic manner. Mulch basins must undergo periodic maintenance, reshaping or removal of material to maintain surge capacity and to prevent ponding and runoff. Microbial activity within the mulch basins will result in decomposition of organic material. To maintain the required storage volume and soil permeability, the mulch beds must undergo routine maintenance. This requirement was based on the 2013 California Plumbing Code.
* Graywater for toilet and urinal flushing use must be disinfected. Graywater research indicates that graywater is to be expected to contain human pathogens. Therefore, the commission is using a multi-barrier approach, including the addition of a potent disinfectant to inhibit the presence of organisms, pathogens and viruses in the graywater distribution system.
* Graywater treatment works that utilize chlorine for disinfection must have a minimum of 0.2 mg/L and a maximum of 4.0 mg/L of free chlorine residual throughout the indoor plumbing system, including fixtures. The free chlorine residual requirement is generally consistent with Regulation #11. The commission is not implying that graywater for indoor toilet and urinal flushing must be treated to potable water standards, as defined by Regulation #11, but that a free chlorine residual range of 0.2 to 4.0 mg/L is reliably detectable and not high enough to adversely impact plumbing fixtures.
* Single family graywater treatment works that utilize non-chemical methods, such as UV, for disinfection must have a chlorine puck present in each toilet tank. The commission wants to give some flexibility to Category C systems and not require chlorine injection for all systems. Since some disinfectants, such as UV, do not have a residual present in the distribution system, a chlorine puck will inhibit the presence of organisms, pathogens, and viruses within the toilet tank and bowl.
* Graywater for toilet and urinal flushing must be dyed with either blue or green food grade vegetable dye and be visibly distinct from potable water. The commission adopted this requirement from the 2012 International Plumbing Code. Dye is a visual indicator that the water within the building is non-potable. Because single family households are not required to have signage for indoor toilet flushing, the dye serves as the notification method that a cross connection has occurred and graywater is entering the potable water lines of the operation.
For dispersed subsurface irrigation, the commission's intention with the design criteria is to protect the subsurface irrigation system from failure. The commission anticipates that without filtration, graywater irrigation systems would fail in a similar manner to an OWTS soil treatment area. Therefore, the commission is requiring filtration prior to the irrigation distribution system to inhibit failure of the emitter systems by particulate or bio-growth clogging. Irrigation system failure will result in surfacing graywater, unequal distribution, and discharge to groundwater.
For subsurface irrigation mulch basin systems, the commission's intention is to ensure that the mulch basin has an adequate volume for surge events and that the soil is capable of adsorption of any excess graywater that is not utilized by the flora. Mulch basin system failure will result in clogged mulch basins, surfacing graywater, and excessive discharge to groundwater.
For indoor toilet and urinal flushing, the commission is requiring a treatment technology that will be protective of public health and will consistently treat graywater without on-going water quality testing. Graywater research indicates that graywater is to be expected to contain human pathogens. Graywater is an emerging research area and peer reviewed research regarding graywater as a potential disease vector and treatment technology impacts on human pathogens are limited. Until additional graywater research studies indicate a definite public health safety threshold, the commission selected the ANSI/NSF 350-2011 standard for indoor toilet and urinal flushing. ANSI/NSF 350 is a performance based treatment testing protocol which requires a third party review of water quality data. The ANSI/NSF 350 standard is required in the 2015 International Plumbing Code and is required by other western states that allow indoor toilet flushing with graywater. The 2013 California Plumbing Code sets ANSI/NSF 350 as the minimum water quality standards (unless the authority having jurisdiction has other water quality requirements). Oregon allows indoor use with an ANSI certified graywater standard. In addition to ANSI/NSF 350 treatment, the commission is requiring dye to visually differentiate graywater from potable water, as well as requiring a disinfectant to prevent biological growth in the graywater distribution system.
The commission is adopting graywater flow rates based on the 2012 Uniform Plumbing Code. The 2012 Uniform Plumbing Code includes daily flow estimates for water saving fixtures while the 2015 International Plumbing Code only has traditional fixture daily flow estimates. The commission received comments from local agencies indicating that the allowed occupancy rates and therefore overall flow rate projections are not very conservative. The commission determined that if graywater is produced at graywater treatment works designed with a storage tank at a rate higher than the estimates, that any excess graywater will overflow to a combined sewer system. Excess graywater production will not impact the graywater treatment works flow (after the storage tank) for graywater use and the overall flow to the closed sewerage system from the facility will not be impacted.
For mulch basin systems without a storage tank, excess graywater production may have a more direct impact. A mulch basin without a storage tank, which is sized for surge events at three times the daily production volume, provides some safety factor for additional daily flow. The local implementing agencies will have the flexibility to adopt more conservative flow rates. For multi-family residential systems, this flow projection design criteria allows flexibility if site specific flow information is available. The residential flow values are intended for circumstances where site specific fixture information is unknown.
The commission is adopting general design criteria for all graywater treatment works including: component sizing requirements, a graywater diversion valve, no bypass lines around the treatment works, and labeling. Treatment works components must be sized to treat the anticipated peak flow rate. For example: an improperly sized filter upstream of a storage tank may result in graywater backing up into the building's plumbing system. The diversion valve is a critical component for the graywater user to allow graywater to be sent to the closed sewerage system during non-irrigation periods, divert graywater when cleaning the tank, divert graywater when hazardous chemical are being used in the building, etc. The diversion valve is intended to direct graywater prior to the graywater treatment works to a closed sewerage system. No bypass lines around the graywater treatment works prior to use is allowed. The graywater lines must also be clearly distinguished to guarantee that the graywater piping is not mistaken for potable water piping. This requirement is intended to be consistent with the anticipated Colorado Plumbing Code requirements but will apply to all graywater piping, including piping outside the structure.
This regulation is consistent with the requirements for onsite wastewater treatment facilities with respect to: the impact of a graywater system on the onsite wastewater treatment facility sizing, floodplain, and floodway requirements. The onsite wastewater treatment system must be sized for the potentially full wastewater treatment flow from the facility in the event that future property owners elect to discontinue use of the graywater treatment works.
The commission determined that a storage tank is required for all graywater treatment works, except for properly sized mulch basin systems. Tanks equalize flow surges and minimize water quality variations through the day. Tanks also allow graywater application to be controlled to ensure agronomic rate control. If excess graywater is produced (over the agronomic rate), the excess graywater will be sent to the closed sewerage system via the overflow line rather than being disposed of in the subsurface irrigation system. Tanks can be used as a collection reservoir for a pressurized graywater distribution system which will allow for equal distribution of graywater throughout graywater piping. For indoor tanks, the Colorado Plumbing code may be more restrictive than the requirements in this regulation, but the design criteria adopted here set minimum standards for water quality needs. The required tank appurtenances are important design features necessary for maintaining the required control measures. Design criteria were included for tank materials, access openings, vents, overflow lines, drains, tank foundation, and signage. A minimum tank volume of 50 gallons was adopted based on the 2012 Uniform Plumbing Code. Outdoor tanks must be protected from direct sunlight to limit biological growth prior to use of stored water.
Some graywater treatment works will produce backwash waste streams. The backwash waste stream must be properly contained or disposed. An example of a graywater treatment works with a produced wastewater stream would be a filter with a backwash process. Any wastewater from the treatment process must be sent to an appropriate disposal location such as a closed sewerage system or an approved Underground Injection Control well.
Graywater treatment works must be located within the confines of the legal property boundary and not within an easement.
In order to ensure the integrity of the irrigation system, the commission is requiring a filter. The filter must be located between the treatment system and the irrigation distribution system to inhibit failure of the soil or emitter systems by particulate clogging. A 60 mesh filter was determined to be the appropriate minimum size for protection of the irrigation system. However, the irrigation system manufacturer may recommend smaller filter sizes based on the selected graywater irrigation system components. Local governments can be more stringent and require designers to follow the manufacturer's recommendations. Prefiltration is not required but is recommended to reduce maintenance on the 60 mesh filter. The filter must be located between the tank and the irrigation area. To prevent pump failure, the filter must be located after the pump and not on the suction side of the pump.
For mulch basin systems, the commission's aim was to not require a filter and to allow for simple graywater systems. It is anticipated that the mulch and underlying soil will act similar to a trickling filter and will provide some treatment of graywater that is not used by the flora.
The commission is adopting different cross-connection control requirements for a graywater system served by a public water system (as defined in Regulation #11) than for graywater systems served by a non-public water system. The commission believes that installation of control devices is critical at all graywater treatment works with potable water connections. However, the commission does not want to require annual device testing for non-public water system users and customers (e.g., a single family house on an individual private well) that would not be required under the commission's existing regulations. The cross connection control requirements for public water systems are well defined in Regulation #11 and therefore this regulation does not repeat the associated requirements. For urinal and toilet flushing users, potable water supply is required for sanitary purposes since toilets and urinals must have a water supply at all times. For subsurface irrigation users, a potable water supply is optional.
The regulation requires signage for public notification. The signage requirement is for non-single family users since the building occupants and visitors are less likely to be aware that a graywater treatment works is in use than at a single family residence. The required signage is for general notification and is a component of the required control measures. For non-single family users, signs are required at three locations:
NSF/ANSI 350-2011 is a performance based water quality standard developed by the NSF Joint Committee on Wastewater Technology in 2011 for residential and commercial graywater treatment for indoor toilet and urinal flushing. The standard sets the minimum design, material, design and construction, and performance requirements for on-site residential and commercial graywater treatment systems. Technologies are tested under normal operating conditions and stress conditions and water quality results are verified by a third party certification agency. The standard does not specify the treatment technologies used to meet the water quality standard which gives flexibility of various treatment technologies to get certified. The commission finds that the ANSI/NSF standard meets an acceptable technology review protocol that would be certified by a third party agency to simplify the technology review process for the local jurisdictions. In addition, ANSI/NSF is a nationally recognized standard that is intended to be protective of public health and would consistently treat graywater without the need for on-going water quality testing. As the ANSI/NSF certification standard is relatively recent only a few manufacturers have gone through the certification process. The commission anticipates that as indoor graywater use becomes more accepted, more manufacturers will certify their products. Additionally, the ANSI/NSF 350 standard has on-site performance testing and evaluation protocol for commercial systems over 1,500 gallons per day. The commission anticipates some graywater users will use a third party testing agency to certify their graywater treatment works to the NSF/ANSI 350 standard.
Graywater research indicates that graywater is to be expected to contain human pathogens; therefore, the commission considers the use of a potent disinfectant an essential part of a multi-barrier approach to protect public health. The use of a disinfectant is required if disinfection is not already part of the ANSI/NSF equipment. The disinfectant is to inhibit the growth of microorganisms, pathogens and viruses in the indoor graywater plumbing system. For non-single family systems, the commission is requiring a free chlorine residual of 0.2 mg/L to 4 mg/L to prevent regrowth of microorganism in the graywater distribution system. Non-single family users are expected to have a large potentially impacted population and a more complicated distribution system design than single family systems. To reduce the burden on single family users, systems that use non-chemical methods for disinfection are required to use a chlorine puck in the toilet or urinal.
To maintain a multi-barrier approach, the commission is requiring that the disinfection process be capable of producing free chlorine rather than total chlorine. The disinfection process for non-single family users must be capable of injecting enough chlorine to react with all reducing agents, ammonium, organics, etc present in the graywater (aka past the breakpoint chlorination point) and that free chlorine must be present. EPA documents indicate that chloramines (which are formed prior to breakpoint chlorination) are approximately 100 times less effective than free chlorine at inactivating pathogens such as Giardia lamblia or viruses. Therefore, the commission believes that free chlorine is a readily available and safe, potent disinfectant.
The professional engineer requirement for graywater treatment works with a design capacity greater than 2,000 gallons per day was determined to be necessary to ensure the protection of public health and the environment. The local jurisdiction may elect to make designer requirements more stringent in their graywater control program.
The irrigation design requirements in this regulation are modeled after the State of Washington's graywater regulation (Chapter 246-274 WAC). Washington requires that graywater be applied directly to the plant root zone. The requirement that irrigation systems be located four (4) inches below ground rather than two (2) inches results in less potential graywater surfacing or accidental breakage incidents. The commission wants to be in general conformance with the required set back distance requirements.
The requirements adopted for single family dispersed subsurface irrigation systems are intended to prevent undersizing of the subsurface irrigation area while making the application process straightforward. For non-single family dispersed subsurface irrigation systems and mulch basin systems, the commission's intent was to adequately size the irrigation system using the best information available including site specific soil testing.
The intention with the dispersed subsurface irrigation systems area sizing was to have a reasonable and simple calculation for single family systems. The commission believes this equation is the simplest and most economical method to estimate the landscape area for small graywater systems. The equation is used by other state agencies (e.g., Idaho, Washington) and designers (e.g., Oasis Design). Furthermore, this method does not require soils testing at each single family residential site. Local jurisdictions that are not comfortable without soils testing results may elect to require the mulch bed or Category B requirements for the single family dispersed subsurface irrigation systems.
The commission modeled the Category B and mulch basin irrigation design requirements on the State of Washington's graywater regulation (Chapter 246-274 WAC). The Washington soil type table was merged with the soil type descriptions in Regulation #43 for ease of local implementation and for consistency between commission regulations. The soil depths are not the same as the Regulation #43 requirements since Regulation #43 is intended for onsite wastewater treatment while this regulation is intended for graywater use by flora. Although intended for use by flora, the mulch basin system design criteria recognize that disposal to groundwater may result. This recognition is the basis for requiring a site and soil evaluation for all mulch basin systems, even single family systems. The site and soil evaluation requirement aims to provide site specific conditions design parameters to allow proper design for category B and mulch basin systems.
Mulch basin design requirements in other western states were researched, and detailed mulch basin design parameters were not found. Therefore the commission's goal for the mulch basin design criteria was to have sufficient volume to adsorb graywater volume surges for graywater treatment works. For graywater treatment works that do not have a storage tank the volume requirements are to capture a surge volume three (3) times the daily flow. For graywater treatment works with a storage tank the volume requirement has a safety factor of 1.5 times the daily flow. The purposes of the other mulch basin design criteria are for proper operation and to minimize potential human exposure.
5 CCR 1002-86.21