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SECTION P2902 PROTECTION OF POTABLE WATER SUPPLY

P2902.1 General.
A potable water supply system shall be designed and installed as to prevent contamination from nonpotable liquids, solids or gases being introduced into the potable water supply. Connections shall not be made to a potable water supply in a manner that could contaminate the water supply or provide a cross-connection between the supply and a source of contamination unless an approved backflow-prevention device is provided. Cross-connections between an individual water supply and a potable public water supply shall be prohibited.

P2902.2 Plumbing fixtures.
The supply lines and fittings for every plumbing fixture shall be installed to prevent backflow. Plumbing fixture fittings shall provide backflow protection in accordance with ASME A112.18.1.

P2902.3 Backflow protection.
A means of protection against backflow shall be provided in accordance with Sections P2902.3.1 through P2902.3.6. Backflow prevention applications shall conform to Table P2902.3, except as specifically stated in Sections P2902.4 through P2902.5.5.

 

TABLE P2902.3 APPLICATION FOR BACKFLOW PREVENTERS

DEVICE
DEGREE OF HAZARDa
APPLICATIONb
APPLICABLE
STANDARDS
Air gap
High or low hazard
Backsiphonage or backpressure ASME A112.1.2
Air gap fittings for use with plumbing fixtures, appliances and appurtenances
High or low hazard
Backsiphonage or backpressure ASME A112.1.3
Antisiphon-type fill valves for gravity water closet flush tanks
High hazard
Backsiphonage only ASSE 1002,
CSA B125.3
Backflow preventer with intermediate atmospheric vents
Low hazard
Backpressure or backsiphonage
Sizes 1/4″-3/4
ASSE 1012,
CSA B64.3
Double check backflow prevention assembly and double check fire protection backflow prevention assembly
Low hazard
Backpressure or backsiphonage
Sizes 3/8″- 16″
ASSE 1015, AWWA C510,
CSA B64.5, CSA B64.5.1
Double check detector fire protection backflow prevention assemblies
Low hazard
Backpressure or backsiphonage
(Fire sprinkler systems)
Sizes 2″- 16″
ASSE 1048
Dual-check-valve-type backflow preventer
Low hazard
Backpressure or backsiphonage
Sizes 1/4″- 1″
ASSE 1024, CSA B64.6
Hose connection backflow preventer
High or low hazard
Low head backpressure, rated working pressure backpressure or backsiphonage Sizes 1/2″- 1″ ASSE 1052,
CSA B64.2.1.1
Hose-connection vacuum breaker
High or low hazard
Low head backpressure or backsiphonage
Sizes 1/2″,3/4″, 1″
ASSE 1011,
CSA B64.2, CSA B64.2.1
Laboratory faucet backflow preventer
High or low hazard
Low head backpressure and backsiphonage ASSE 1035, CSA B64.7
Pipe-applied atmospheric-type vacuum breaker
High or low hazard
Backsiphonage only
Sizes 1/4″- 4″
ASSE 1001, CSA B64.1.1
Pressure vacuum breaker assembly
High or low hazard
Backsiphonage only
Sizes 1/2″- 2″
ASSE 1020, CSA B64.1.2
Reduced pressure detector fire protection backflow prevention assemblies
High or low hazard
Backsiphonage or backpressure
(Fire sprinkler systems)
ASSE 1047
Reduced pressure principle backflow preventer and reduced pressure principle fire protection backflow preventer
High or low hazard
Backpressure or backsiphonage
Sizes 3/8″- 16″
ASSE` 1013,
AWWA C511,
CSA B64.4, CSA B64.4.1
Spillproof vacuum breaker
High or low hazard
Backsiphonage only
Sizes 1/4″- 2″
ASSE 1056
Vacuum breaker wall hydrants, frost-resistant, automatic draining type
High or low hazard
Low head backpressure or backsiphonage
Sizes 3/4″- 1″
ASSE 1019, CSA B64.2.2


For SI: 1 inch = 25.4 mm.

a. Low hazard-See Pollution (Section R202). High hazard-See Contamination (Section R202).

b. See Backpressure (Section R202). See Backpressure, Low Head (Section R202). See Backsiphonage (Section R202).

P2902.3.1 Air gaps. Air gaps shall comply with ASME A112.1.2 and air gap fittings shall comply with ASME A112.1.3. The minimum air gap shall be measured vertically from the lowest end of a water supply outlet to the flood level rim of the fixture or receptor into which such potable water outlets discharge. The minimum required air gap shall be twice the diameter of the effective opening of the outlet, but in no case less than the values specified in Table P2902.3.1. An air gap is required at the discharge point of a relief valve or piping. Air gap devices shall be incorporated in dishwashing and clothes washing appliances.

TABLE P2902.3.1
MINIMUM AIR GAPS

FIXTURE
MINIMUM AIR GAP
Away from a walla
(inches)
Close to a wall
(inches)
Effective openings greater than 1 inch
Two times the diameter of the effective opening
Three times the diameter of the effective opening
Lavatories and other fixtures with effective opening not greater than 1/2 inch in diameter
1
1.5
Over-rim bath fillers and other fixtures with effective openings not greater than 1 inch in diameter
2
3
Sink, laundry trays, gooseneck back faucets and other fixtures with effective openings not greater than 3/4 inch in diameter
1.5
2.5


For SI: 1 inch = 25.4 mm.
 
a. Applicable where walls or obstructions are spaced from the nearest inside edge of the spout opening a distance greater than three times the diameter of the effective opening for a single wall, or a distance greater than four times the diameter of the effective opening for two intersecting walls.
P2902.3.2 Atmospheric-type vacuum breakers. Pipe-applied atmospheric-type vacuum breakers shall conform to ASSE 1001 or CSA B64.1.1. Hose-connection vacuum breakers shall conform to ASSE 1011, ASSE 1019, ASSE 1035, ASSE 1052, CSA B64.2, CSA B64.2.1, CSA B64.2.1.1, CSA B64.2.2 or CSA B64.7. These devices shall operate under normal atmospheric pressure when the critical level is installed at the required height.
P2902.3.3 Backflow preventer with intermediate atmospheric vent. Backflow preventers with intermediate atmospheric vents shall conform to ASSE 1012 or CAN/CSA B64.3. These devices shall be permitted to be installed where subject to continuous pressure conditions. The relief opening shall discharge by air gap and shall be prevented from being submerged.
P2902.3.4 Pressure-type vacuum breakers. Pressure-type vacuum breakers shall conform to ASSE 1020 or CSA B64.1.2 and spillproof vacuum breakers shall comply with ASSE 1056. These devices are designed for installation under continuous pressure conditions when the critical level is installed at the required height. Pressure-type vacuum breakers shall not be installed in locations where spillage could cause damage to the structure.
P2902.3.5 Reduced pressure principle backflow preventers. Reduced pressure principle backflow preventers shall conform to ASSE 1013, AWWA C511, CSA B64.4 or CSA B64.4.1. Reduced pressure detector assembly backflow preventers shall conform to ASSE 1047. These devices shall be permitted to be installed where subject to continuous pressure conditions. The relief opening shall discharge by air gap and shall be prevented from being submerged.
P2902.3.6 Double check-valve assemblies. Double check-valve assemblies shall conform to ASSE 1015, CSA B64.5, CSA B64.5.1 or AWWA C510. Double-detector check-valve assemblies shall conform to ASSE 1048. These devices shall be capable of operating under continuous pressure conditions.
P2902.4 Protection of potable water outlets. Potable water openings and outlets shall be protected by an air gap, reduced pressure principle backflow preventer with atmospheric vent, atmospheric-type vacuum breaker, pressure-type vacuum breaker or hose connection backflow preventer.

P2902.4.1 Fill valves. Flush tanks shall be equipped with an antisiphon fill valve conforming to ASSE 1002 or CSA B 125.3. The fill valve backflow preventer shall be located at least 1 inch (25 mm) above the full opening of the overflow pipe.
P2902.4.2 Deck-mounted and integral vacuum breakers. Approved deck-mounted vacuum breakers and faucets with integral atmospheric or spill-proof vacuum breakers shall be installed in accordance with the manufacturer's installation instructions and the requirements for labeling with the critical level not less than 1 inch (25 mm) above the flood level rim.
P2902.4.3 Hose connection. Sillcocks, hose bibbs, wall hydrants and other openings with a hose connection shall be protected by an atmospheric-type or pressure-type vacuum breaker or a permanently attached hose connection vacuum breaker.

Exceptions:
1. This section shall not apply to water heater and boiler drain valves that are provided with hose connection threads and that are intended only for tank or vessel draining.
2. This section shall not apply to water supply valves intended for connection of clothes washing machines where backflow prevention is otherwise provided or is integral with the machine.
P2902.5 Protection of potable water connections. Connections to the potable water shall conform to Sections P2902.5.1 through P2902.5.5.

P2902.5.1 Connections to boilers. The potable supply to the boiler shall be equipped with a backflow preventer with an intermediate atmospheric vent complying with ASSE 1012 or CSA B64.3. Where conditioning chemicals are introduced into the system, the potable water connection shall be protected by an air gap or a reduced pressure principle backflow preventer complying with ASSE 1013, CSA B64.4 or AWWA C511.
P2902.5.2 Heat exchangers. Heat exchangers using an essentially toxic transfer fluid shall be separated from the potable water by double-wall construction. An air gap open to the atmosphere shall be provided between the two walls. Heat exchangers utilizing an essentially nontoxic transfer fluid shall be permitted to be of single-wall construction.
P2902.5.3 Lawn irrigation systems. The potable water supply to lawn irrigation systems shall be protected against backflow by an atmospheric-type vacuum breaker, a pressure-type vacuum breaker or a reduced pressure principle backflow preventer. A valve shall not be installed downstream from an atmospheric vacuum breaker. Where chemicals are introduced into the system, the potable water supply shall be protected against backflow by a reduced pressure principle backflow preventer.
P2902.5.4 Connections to automatic fire sprinkler systems. The potable water supply to automatic fire sprinkler systems shall be protected against backflow by a double check-valve assembly or a reduced pressure principle backflow preventer.

Exception:
Where systems are installed as a portion of the water distribution system in accordance with the requirements of this code and are not provided with a fire department connection, isolation of the water supply system shall not be required.
P2902.5.4.1 Additives or nonpotable source. Where systems contain chemical additives or antifreeze, or where systems are connected to a nonpotable secondary water supply, the potable water supply shall be protected against backflow by a reduced pressure principle backflow preventer. Where chemical additives or antifreeze is added to only a portion of an automatic fire sprinkler or standpipe system, the reduced pressure principle backflow preventer shall be permitted to be located so as to isolate that portion of the system.
P2902.5.5 Solar systems. The potable water supply to a solar system shall be equipped with a backflow preventer with intermediate atmospheric vent complying with ASSE 1012 or a reduced pressure principle backflow preventer complying with ASSE 1013. Where chemicals are used, the potable water supply shall be protected by a reduced pressure principle backflow preventer.

Exception:
Where all solar system piping is a part of the potable water distribution system, in accordance with the requirements of the International Plumbing Code, and all components of the piping system are listed for potable water use, cross-connection protection measures shall not be required.
P2902.6 Location of backflow preventers. Access shall be provided to backflow preventers as specified by the manufacturer's installation instructions.

P2902.6.1 Outdoor enclosures for backflow prevention devices. Outdoor enclosures for backflow prevention devices shall comply with ASSE 1060.
P2902.6.2 Protection of backflow preventers. Backflow preventers shall not be located in areas subject to freezing except where they can be removed by means of unions, or are protected by heat, insulation or both.
P2902.6.3 Relief port piping. The termination of the piping from the relief port or air gap fitting of the backflow preventer shall discharge to an approved indirect waste receptor or to the outdoors where it will not cause damage or create a nuisance.