Chapter 6 — WATER SUPPLY AND DISTRIBUTION

603.2 Approval of Devices or Assemblies. Before a

California Plumbing Code (Title 24, Part 5) · 2022 edition · updated 2026-09-10 · California

Italicized text is a California amendment to the model code, as printed in the official publication.

device or an assembly is installed for the prevention of backflow, it shall have first been approved by the Authority Having Jurisdiction. Devices or assemblies shall be tested in accordance with recognized standards or other standards acceptable to the Authority Having Jurisdiction. Backflow prevention devices and assemblies shall comply with Table 603.2, except for specific applications and provisions as stated in Section 603.5.1 through Section 603.5.21.

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TABLE 603.2 BACKFLOW PREVENTION DEVICES, ASSEMBLIES, AND METHODS
DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD
DEVICE, ASSEMBLY, OR METHOD1	APPLICABLE STANDARDS	POLLUTION (LOW HAZARD)	POLLUTION (LOW HAZARD)	CONTAMINATION (HIGH HAZARD)	CONTAMINATION (HIGH HAZARD)	INSTALLATION2,3
DEVICE, ASSEMBLY, OR METHOD1	APPLICABLE STANDARDS	BACK- SIPHONAGE	BACK- PRESSURE	BACK- SIPHONAGE	BACK- PRESSURE	BACK- PRESSURE
Air gap	ASME A112.1.2	X	––	X	––	See Table 603.3.1 in this chapter.
Air gap fittings for use with plumbing fixtures, appliances, and appurte- nances	ASME A112.1.3	X	––	X	––	Air gap fitting is a device with an internal air gap, and typical installation includes plumbing fixtures, appliances, and appurtenances. The critical level shall not be installed below the flood level rim.
Atmospheric vacuum breaker (consists of a body, checking member and atmospheric port)	ASSE 1001 or CSA B64.1.1	X	––	X	––	Upright position. No valve downstream. Minimum of 6 inches or listed distance above all downstream piping and flood level rim of receptor.4,5
Antisiphon fill valve (ballcocks) for gravity water closet flush tanks and urinal tanks	ASSE 1002/ ASME A112.1002/ CSA B125.12	X	––	X	––	Installation of gravity water closet flush tank and urinal tanks with the fill valve installed with the critical level not less than 1 inch above the opening of the overflow pipe.4,5
Vacuum breaker wall hydrants, hose bibbs, freeze resistant, auto- matic draining type	ASSE 1019 or CSA B64.2.1.1	X	––	X	––	Installation includes wall hydrants and hose bibbs. Such devices are not for use under con- tinuous pressure conditions (means of shutoff downstream of device is prohibited).4,5
Hose connection vacuum breakers	ASSE 1011	X	––	X	––	Such devices are not for use under continuous pressure conditions. No valve downstream.4,6
Hose connection back- flow preventers	ASSE 1052	X	––	X	––	Such devices are not for use under continuous pressure conditions.4,6
Dual check backflow preventer	ASSE 1024	X	X	—	—	Installation does not include carbonated drink dispensers.
Dual check backflow preventer wall hydrants, freeze resistant	ASSE 1053	X	––	X	––	Such devices are not for use under continuous pressure conditions.4
Freeze resistant sanitary yard hydrants	ASSE 1057	X	––	X	––	Such devices are not for use under continuous pressure conditions.4
Backflow preventer with intermediate atmospheric vent	ASSE 1012	X	X	—	—	Installation of potable water connections to water boilers. No high-hazard chemicals shall be introduced into the system using such devices. Designed to operate under con- tinuous pressure conditions. May discharge water.
Backflow preventer with intermediate atmospheric vent and pressure reduc- ing valve	ASSE 1081	X	X	—	—	Installation of potable water connections to water boilers. No high-hazard chemicals shall be introduced into the system using such devices. Designed to operate under con- tinuous pressure conditions. May discharge water.
Backflow preventer for Carbonated Beverage Dispensers (two inde- pendent check valves with a vent to the atmos- phere)	ASSE 1022	X	––	––	––	Installation includes carbonated beverage machines or dispensers. These devices operate under intermittent or continuous pressure conditions.
Spill-Resistant Pressure Vacuum Breaker (single check valve with air inlet vent and means of field testing)	ASSE 1056	X	––	X	––	Upright position. Minimum of 12 inches or listed distance above all downstream piping and flood-level rim of receptor.5

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TABLE 603.2 BACKFLOW PREVENTION DEVICES, ASSEMBLIES, AND METHODS (continued)
DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD	DEGREE OF HAZARD
DEVICE, ASSEMBLY, OR METHOD1	APPLICABLE STANDARDS	POLLUTION (LOW HAZARD)	POLLUTION (LOW HAZARD)	CONTAMINATION (HIGH HAZARD)	CONTAMINATION (HIGH HAZARD)	INSTALLATION2,3
DEVICE, ASSEMBLY, OR METHOD1	APPLICABLE STANDARDS	BACK- SIPHONAGE	BACK- PRESSURE	BACK- SIPHONAGE	BACK- PRESSURE	BACK- PRESSURE
Double Check Valve Backflow Prevention Assembly (two inde- pendent check valves and means of field test- ing)	ASSE 1015; AWWA C510; CSA B64.5 or CSA B64.5.1	X	X	––	––	Horizontal unless otherwise listed. Access and clearance shall be in accordance with the manufacturer’s instructions, and not less than a 12 inch clearance at the bottom for maintenance. May need platform/ladder for test and repair. Does not discharge water.
Double Check Detector Fire Protection Backflow Prevention Assembly (two independent check valves with a parallel detector assembly con- sisting of a water meter and a double check valve backflow prevention assembly and means for field testing)	ASSE 1048	X	X	––	––	Horizontal unless otherwise listed. Access and clearance shall be in accordance with the manufacturer’s instructions, and not less than a 12 inch clearance at the bottom for maintenance. May need platform/ladder for test and repair. Does not discharge water. Installation includes a fire protection system and is designed to operate under continuous pressure conditions.
Pressure Vacuum Breaker Backflow Pre- vention Assembly (loaded air inlet valve, internally loaded check valve and means for field testing)	ASSE 1020 or CSA B64.1.2	X	––	X	––	Upright position. May have valves down- stream. Minimum of 12 inches above all downstream piping and flood-level rim of the receptor. May discharge water.
Reduced Pressure Princi- ple Backflow Prevention Assembly (two independ- ently acting loaded check valves, a differential pressure relief valve and means for field testing)	ASSE 1013; AWWA C511; CSA B64.4 or CSA B64.4.1	X	X	X	X	Horizontal unless otherwise listed. Access and clearance shall be in accordance with the manufacturer’s instructions, and not less than a 12 inch clearance at the bottom for maintenance. May need platform/ladder for test and repair. May discharge water.
Reduced Pressure Detec- tor Fire Protection Back- flow Prevention Assembly (two inde- pendently acting loaded check valves, a differen- tial pressure relief valve, with a parallel detector assembly consisting of a water meter and a reduced-pressure princi- ple backflow prevention assembly, and means for field testing)	ASSE 1047	X	X	X	X	Horizontal unless otherwise listed. Access and clearance shall be in accordance with the manufacturer’s instructions, and not less than a 12 inch clearance at the bottom for maintenance. May need platform/ladder for test and repair. May discharge water. Installation includes a fire protection system and is designed to operate under continuous pressure conditions.
Laboratory faucet back- flow preventer	ASSE 1035	––	––	X	X	Installation includes laboratory faucets. Such devices are not for use under continuous pressure conditions. No valve downstream.4

For SI units: 1 inch = 25.4 mm Notes: 1 See the description of devices and assemblies in this chapter. 2 Installation in pit or vault requires previous approval by the Authority Having Jurisdiction. 3 Refer to the general and specific requirement for installation. 4 Not to be subjected to operating pressure for more than 12 hours in a 24 hour period. 5 For deck-mounted and equipment-mounted vacuum breaker, see Section 603.5.13. 6 Shall be installed in accordance with Section 603.5.7.

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Devices or assemblies installed in a potable water supply system for protection against backflow shall be maintained in good working condition by the person or persons having control of such devices or assemblies. Such devices or assemblies shall be tested at the time of installation, repair, or relocation and not less than on an annual schedule thereafter, or more often where required by the Authority Having Jurisdiction. Where found to be defective or inoperative, the device or assembly shall be repaired or replaced. No device or assembly shall be removed from use or relocated or other device or assembly substituted, without the approval of the Authority Having Jurisdiction.

Testing or maintenance shall be performed by a certified backflow assembly tester or repairer in accordance with ASSE Series 5000 or otherwise approved by the Authority Having Jurisdiction.