Part III. Design and Installation
12VAC5-635-200. Cross-connection abatement.
No rainwater harvesting system may be installed, operated, or allowed on any premises where cross-connection to a waterworks or a private well exists, unless the cross-connections are abated or controlled by means including cross-connection control and backflow prevention in accordance with the USBC. Where cross-connection to a waterworks exists, the cross-connection shall be abated or controlled to the satisfaction of the waterworks.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-210. Backflow prevention.
A. A rainwater harvesting system shall be designed, installed, and maintained to prevent contamination of secondary water supplies by backflow. Backflow prevention shall be achieved by one or more of the following:
1. Backflow elimination methods, including air gap separation or physical disconnection;
2. Backflow prevention assemblies, including the reduced pressure principle, double check valve, and pressure vacuum breaker assemblies; or
3. If backflow prevention is not generally required to withstand continuous pressure over 12 hours or to control high hazards, a backflow prevention device, including atmospheric type vacuum breakers and dual check valve devices.
B. Backflow prevention assemblies and backflow prevention devices shall be suitable to the application and shall conform to the USBC.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-220. Water storage unit location.
A. An underground water storage unit for a rainwater harvesting system shall be sited with appropriate consideration given to distance from potential contamination sources, vulnerability to known or suspected natural risks (e.g., flooding and sink holes), potential for interference with utilities, and safety.
B. If the rainwater harvesting system will include an underground installation of a water storage unit, the designer shall conduct a sanitary survey, including investigation of obvious sources of toxic or dangerous substances within 200 feet of the water storage unit. Sources of contamination may include items listed in Table 1. The minimum separation distance between an underground water storage unit and sources of contamination shall comply with the minimum distances shown in Table 1.
TABLE 1 Separation distance between underground water storage unit and potential source of contamination | |
Potential Source of Contamination | Separation Distance (feet) |
Active or permitted septic tank, holding tank, pump tank, aerobic unit, house sewer line, sewer line, sewer main, sewerage system | 50 |
Active or permitted drainfield, including reserve drainfield | 50 |
Permanently abandoned onsite sewage disposal system | 35 |
Petroleum storage tank, drum, tote, or other container (underground) | 100 |
Petroleum storage tank, drum, tote, or other container (aboveground) | 50 |
C. An aboveground water storage unit shall be installed on a sturdy and level foundation or platform with adequate drainage capable of bearing the weight of the unit at capacity. If multiple storage units are connected, compliant fittings must be used and installed in a manner that provides adequate flexibility to allow for unit settlement or movement.
D. A water storage unit and associated pipes and pipe fittings and appurtenances to be installed in locations subject to direct sunlight shall be constructed of materials stable under ultraviolet light exposure anticipated over the life of the system.
E. A water storage unit shall be supported and restrained to prevent lateral movement. Support and restraint devices may not be placed in a manner that will obstruct access for cleaning and maintenance.
F. A water storage unit subject to a shallow water table shall be ballasted or otherwise secured to prevent floatation or lateral movement. The unit shall be designed to withstand structural stresses of hydrostatic pressure and buoyancy. If partially buried, design shall include provision to withstand the weight of backfill.
G. A water storage unit subject to vehicular traffic shall be installed in accordance with manufacturer's installation instructions and the USBC.
H. A water storage unit shall have at least one access opening to allow inspection and cleaning of the unit interior. The access opening shall be located to facilitate pumping and servicing of inlets and outlets. The access opening shall be locked or otherwise secured to prevent unauthorized access and shall be located at a finished grade such that surface water ponding does not occur under annual precipitation extreme conditions.
I. A water storage unit shall be fitted with an overflow discharge system with the following requirements:
1. Overflow is not less than the capacity of the inlets;
2. Unit overflow pipes are protected from insects and vermin;
3. Piping associated with unit overflow discharges water away from the unit and in accordance with the USBC;
4. Discharge of unit overflow is directed to prevent hazardous conditions;
5. No shutoff valves are incorporated into discharge piping;
6. Cleanouts are provided on overflow piping in accordance with the USBC;
7. If connected to storm drainage systems, the storm drainage systems have a means to prevent backflow; and
8. Overflows are not directed to onsite sewage systems or sanitary sewers.
J. A water storage unit shall be fitted with a vent pipe having a minimum 38.1 mm diameter protected with 1.5 mm mesh to prevent the entry of vermin and particulates.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-230. Materials and equipment.
A. Materials and equipment used in rainwater harvesting systems shall be labeled to demonstrate compliance with applicable NSF 61 and NSF P151 standards, as appropriate.
B. Collection surfaces shall comply with the following requirements:
1. Collection roofing are composed of non-toxic materials;
2. Paint used on surfaces used for collection of rainwater for potable purposes is labeled to be certified to NSF/ANSI/CAN Standard 61-2020 or P151 and applied per the manufacturer's installation instructions;
3. Lead-based, chromium-based, or zinc-based paints are not used;
4. Galvanized metal is not used;
5. Flat roof products are labeled as meeting NSF Protocol P151;
6. Equipment and appliances mounted on collection surfaces have a means of preventing the introduction of contaminants into the rainwater harvesting system;
7. Equipment and appliances containing toxic fluids or other potentially harmful substances are not installed on collection surfaces or in locations where a release of contained substances will flow by gravity to collection surfaces; and
8. Materials used for collection surfaces conform to end use tier criteria pursuant to Table 2.
TABLE 2. Collection Surface Materials | |
Roofing Material (including flashing) | Acceptable for End Use Tier |
Asbestos cement | Not acceptable for any end use |
Asphalt | 1, 2, 3, 4 |
Asphalt felt and bituminous and tar membranes | 1, 2, 3 |
Ceramic | 1, 2, 3, 4 |
Clay | 1, 2, 3, 4 |
Concrete | 1, 2, 3, 4 |
Copper | 1, 2, 3 |
Fiberglass | 1, 2, 3, 4 |
Glass | 1, 2, 3, 4 |
Polyethylene membrane | 1, 2, 3, 4 |
Polymer and acrylic | 1, 2, 3 |
Rubber/Butyl/EPDM membrane | 1, 2, 3 |
Steel, coated | 1, 2, 3, 4 |
Steel, stainless | 1, 2, 3, 4 |
Tin | 1, 2, 3, 4 |
Wood, untreated | 1, 2, 3 |
Wood, treated | 1, 2, 3 |
PVC | 1, 2, 3, 4 |
TPO | 1, 2, 3 |
Public pedestrian accessible roofs | 1, 2, 3 |
Vegetated roofs | 1, 2, 3 |
Pedestrian and parking surfaces (rooftop) | 1, 2, 3 |
C. The conveyance system shall be protected to prevent the entrance of vermin. Inlets, debris excluders, filters, first-flush diverters, cleanouts, and conveyance system components requiring service shall be accessible. To convey captured rainwater, rainwater harvesting systems shall use drainage piping suitable for use with plumbing drainage or pressure systems. Conveyance system materials shall be labeled to demonstrate compliance with NSF/ANSI/CAN Standard 61-2020.
D. A cistern or water storage unit, liners, coatings, pipes, pipe fittings, and appurtenances shall be labeled to demonstrate compliance with the applicable requirements of NSF 61/ANSI/CAN Standard 61-2020 and NSF 372. The water storage unit shall be manufactured from previously unused materials, and no cistern or storage unit previously used to store anything other than water may be incorporated into a rainwater harvesting system. The water storage unit may be installed either above or below grade and provided a means for emptying and cleaning. If gravity drainage is not possible, a provision for pumping water from the unit shall be provided.
E. Water contained in an aboveground water storage unit shall be protected from direct sunlight through the use of opaque, ultraviolet-resistant materials or a sun barrier.
F. An underground water storage unit shall be installed in compliance with U.S. Occupational Safety and Health Administration Standard 1926 Subpart P and shall be provided with manhole risers a minimum of six inches above surrounding grade.
G. Pump and pump components shall be capable of delivering a minimum of 15 pounds per square inch in gauge residual pressure at the highest and most remote outlet served. Maximum pressure should not exceed 80 pounds per square inch in gauge.
H. Water piping, fittings, and related system components shall be appropriate for use in accordance with the USBC. Where plastic piping is exposed to sunlight, it shall be protected by a factory applied protective coating or painted with compatible latex paint.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-240. Design and installation.
A. The rainwater harvesting system shall be designed, installed, operated, and maintained to prevent contamination of water supplies and distribution piping.
B. Rainwater harvesting system components shall be protected from external contamination and entry by insects and vermin.
C. The rainwater harvesting system shall be sited and designed to produce and store water under local site conditions that include:
1. Excessive heat;
2. Freezing;
3. Flooding; and
4. Sunlight exposure.
D. The owner shall control access to rainwater harvesting system components to minimize unauthorized access.
E. Gutters, downspouts, and conveyance systems leading to the water storage unit shall be fitted with a screen or debris excluder to prevent the accumulation of leaves, needles, or other debris into the water storage tank or cistern.
F. Vegetation above roofs and gutters shall be removed to reduce organic matter falling on and decomposing in rainwater collection surfaces and conveyances, and to reduce or remove locations for animals to introduce contaminants.
G. Rainwater shall pass through a prefiltration system prior to entering the water storage unit or cistern. Appropriate prefiltration devices include a gutter screen, inline filters, and vortex filters to reduce organic matter, debris, and particulates from entering and accumulating in the bottom of the unit or cistern. Prefiltration devices without a self-cleaning design shall incorporate a corrosion-resistant debris screen having openings no larger than 0.15 cm.
H. A first flush device shall be used to remove accumulated debris from the collection surface before rainwater is introduced to the water storage unit. First flush diverters shall:
1. Be placed after prefiltration;
2. Operate automatically and not rely on mechanically operated valves or devices;
3. Discharge diverted rainwater in a manner consistent with local stormwater runoff requirements so as not to cause damage to a property or erosion; and
4. Be readily accessible for maintenance.
I. Inlets and outlets on the water storage unit shall be installed and supported in accordance with the manufacturer's instructions. Water storage units, including units used in series, shall each be fitted as follows:
1. Rainwater inlets to a water storage unit shall be arranged to minimize turbulent flow by means of a calming device such as a return bend elbow pointed upward at least 10 cm above the bottom of the tank.
2. Outlets shall be positioned, and floating collared offtakes shall be used below the top water level in the unit to draw water from the cleanest strata of the unit.
3. Overflow outlets or flap valves shall be protected with a screen having openings no greater than 1.5 mm to prevent entrance of insects or vermin into the unit.
4. The vent shall be minimum 38.1 mm diameter and be protected with mesh having openings no greater than 1.5 mm to prevent entrance of vermin and particulates.
5. Rainwater outlets and pump suction shall be located at least 100 mm above the bottom of the unit. If a floating pump is used, it shall draw water from below the water surface.
6. Pipe penetrations through unit walls shall be watertight and shall comply with the USBC. Pipe penetrations shall not prevent access to the unit for inspection or cleaning.
J. A rainwater harvesting system shall be equipped with filtration systems conforming to the standards specified in 12VAC5-635-250 and 12VAC5-635-340 and shall:
1. Be installed in accordance with the USBC;
2. Be accessible for inspection and maintenance;
3. Provide indication when servicing or replacement is due; and
4. Incorporate shutoff valves immediately upstream and downstream to allow for isolation during maintenance.
K. A rainwater harvesting system shall be equipped with disinfection systems that:
1. Conform with the standards specified in 12VAC5-635-260 and 12VAC5-635-340; and
2. Are designed and installed in accordance with the manufacturer's instructions and the USBC.
L. A rainwater harvesting system for Tier 3 and Tier 4 end use shall be equipped with a fail-safe system for disinfection systems, with alerts and alarms as follows:
1. Alerts shall be provided for critical control points identified in the operation and maintenance manual to indicate when the rainwater harvesting system is operating outside design parameters but not causing a hazard to health or safety or damage to system components.
2. Alerts shall have a visible output and may have an audible output.
3. Alarms shall be provided for critical control points identified in the operation and maintenance manual to indicate when the rainwater harvesting system is operating outside the design parameters and potentially causing a hazard to health or safety or damage to system components.
4. Alarms shall have visible and audible outputs.
5. A remote alarm of an alert system using electronic communication shall be used to notify the operator that the system has failed or that failure is imminent.
M. Separation shall be maintained between potable and nonpotable distribution systems by means of color coded and labeled piping and cross-connection control in accordance with the USBC.
N. Controls for rainwater harvesting systems supplying water for fire sprinkler systems or standpipes shall comply with the Virginia Statewide Fire Prevention Code Act (§ 27-94 et seq. of the Code of Virginia).
O. If a rainwater harvesting system is installed in any building, facility, or residence, it shall be so indicated as follows:
1. Fixtures not specifically treated for potable water use shall be labeled for nonpotable use in accordance with the USBC.
2. Fixtures not subject to the USBC and not specifically treated for potable water use shall be prominently labeled "CAUTION: NONPOTABLE WATER – DO NOT DRINK" and "ATTENCIÓN: AGUA NO-POTABLE – NO BEBER." Labels shall be indelibly printed on a tag or sign constructed of a corrosion resistant, waterproof material permanently mounted in a visible location. The letters of the labels and markings shall be at least 0.5 inches in height and shall be of a color that contrasts with the background on which they are printed. In addition to the required words, a pictograph consistent with the following shall appear in the tag or sign:
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-250. Filtration.
A. The owner shall ensure that harvested rainwater for Tier 2, Tier 3, and Tier 4 end uses is filtered.
B. Filtration is not required for Tier 2 end use water used outdoors.
C. If ultraviolet disinfection is used, particulate filtration systems shall be located downstream of the water storage tank and upstream of the ultraviolet system.
D. If ozone or chemical based disinfection is used, particulate filtration systems shall be installed downstream of the disinfection equipment. Filtration shall be installed as required for the disinfection system and in accordance with manufacturer's installation requirements.
E. Filters shall be sized to extend service time and shall be labeled to demonstrate compliance with NSF 42 for the reduction of taste or odor or shall be labeled to demonstrate compliance with NSF 53 for organic and cyst removal based on the end use tier.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-260. Disinfection.
A. The owner shall ensure that harvested rainwater intended for Tier 2, 3, or 4 end use is disinfected and that water meeting the quality standards in 12VAC5-635-310 is delivered to the point of use.
B. The owner shall ensure that disinfection systems are designed and installed in accordance with the manufacturer's instructions and the USBC.
C. If a rainwater harvesting system requires a disinfection system pursuant to this section, the owner shall use one of the following acceptable methods:
1. An ultraviolet (UV) disinfection system that (i) treats water for distribution downstream of the water storage unit and upstream of the point of use; (ii) is sized based on the required dose, taking into consideration the design flow and minimum UV transmittance required to achieve the end use tier standard; and (iii) for Tier 4 end use, is labeled to be certified to Class A of NSF 55;
2. An ozone disinfection system that maintains adequate contact time based on end use tier and off-gasses to a safe environment; or
3. A chemical system that:
a. Has means to measure and control the disinfection and oxidation levels to achieve the performance requirements in 12VAC5-635-310;
b. Uses chemical feed pumps that are controlled to prevent operation unless there is flow through the system;
c. Is labeled to be certified to provide the required log reductions for protozoa and bacteria pursuant to NSF 53 or is labeled to be certified to provide the required log reductions for protozoa and bacteria pursuant NSF/ANSI 419-2018;
d. Uses chemicals that are labeled to demonstrate compliance with NSF/ANSI/CAN Standard 60-2020 if water is provided for Tier 4 end use; and
e. Maintains a chlorine residual of at least 0.5 mg/L and control disinfection byproducts if untreated harvested rainwater is stored at temperatures higher than 77°F and chlorine disinfection is used.
D. A rainwater harvesting system for end use in a single-family home shall only use ultraviolet or ozone disinfection methods.
E. The department may approve other disinfection methods on a case-by-case basis.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-270. General certification.
A. Premanufactured treatment systems and equipment and materials used to assemble treatment systems that are not premanufactured shall be labeled to demonstrate that the systems, equipment, and materials comply with NSF standards, as follows:
1. NSF/ANSI 53-2020 for point-of-entry or point-of-use filtration systems;
2. NSF/ANSI 55-2020 for ultraviolet disinfection systems;
3. NSF/ANSI/CAN 60-2020 for water treatment chemicals;
4. NSF/ANSI/CAN 61-2020 for protective barrier materials, joining and sealing materials, mechanical devices, plumbing devices, pipes, hoses, pipe fittings, process media, and nonmetallic potable water materials; and
5. NSF/ANSI 350-2020 and NSF/ANSI/CAN 350.1-2017 for material, design, construction, and performance requirements for reuse water.
B. Harvested rainwater is not reuse water. However, NSF/ANSI 350-2020 and NSF/ANSI/CAN 350.1-2017 establish baseline standards suitable for equipment and materials used in the design, installation, and operation of rainwater harvesting systems.
C. A person providing design, installation, or inspection of rainwater harvesting systems shall be certified by the American Society of Sanitary Engineering (ASSE) as follows:
1. Rainwater Harvesting System Designers shall maintain ASSE 21120 Rainwater Catchment Systems Designer certification.
2. Rainwater Harvesting System Installers shall maintain ASSE 21110 Rainwater Catchment Systems Installer certification.
3. Rainwater Harvesting System Inspectors shall maintain ASSE 21130 Rainwater and Stormwater Catchment Systems Inspector certification.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.
12VAC5-635-280. Temporary removal from service.
If a rainwater harvesting system is seasonally or temporarily removed from service, the owner or operator shall:
1. Lock out or disable piping connected to a waterworks;
2. Secure water storage units from unauthorized access;
3. Divert inlet piping as necessary; and
4. Disconnect electrical power.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.