Chapter 6 — WATER SUPPLY AND DISTRIBUTION

603.3 Backflow Prevention Devices, Assemblies, andMethods.

California Plumbing Code (Title 24, Part 5) · 2019 edition · updated 2026-09-10 · California

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

Backflow prevention devices, assemblies, and methods shall comply with Section 603.3.1 through Section 603.3.9.

2019 CALIFORNIA PLUMBING CODE 137

WATER SUPPLY AND DISTRIBUTION any other purpose or distributed to any other persons or parti es.

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 continuous 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 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 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
~~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.

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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 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 mainte- nance. 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 pres- sure 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 inde- pendently acting loaded check valves, a differen- tial pressure relief valve and means for field test- ing)	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 mainte- nance. 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 mainte- nance. 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.

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.

2019 CALIFORNIA PLUMBING CODE 139

WATER SUPPLY AND DISTRIBUTION any other purpose or distributed to any other persons or parti es.

603.3.1 Air Gap. The minimum air gap to afford backflow protection shall be in accordance with Table 603.3.1. 603.3.2 Atmospheric Vacuum Breaker (AVB). An atmospheric vacuum breaker consists of a body, a checking member, and an atmospheric port. 603.3.3 Hose Connection Backflow Preventer. A hose connection backflow preventer consists of two independent check valves with an independent atmospheric vent between and a means of field testing and draining. 603.3.4 Double Check Valve Backflow Prevention Assembly (DC). A double check valve backflow prevention assembly consists of two independently acting internally loaded check valves, four properly located test cocks, and two isolation valves. 603.3.5 Pressure Vacuum Breaker Backflow Pre- vention Assembly (PVB). A pressure vacuum breaker backflow prevention assembly consists of a loaded air inlet valve, an internally loaded check valve, two properly located test cocks, and two isolation valves. This device shall be permitted to be installed indoors where provisions for spillage are provided. 603.3.6 Spill-Resistant Pressure Vacuum Breaker (SVB). A pressure-type vacuum breaker backflow prevention assembly consists of one check valve force-loaded closed and an air inlet vent valve forceloaded open to atmosphere, positioned downstream of the check valve and located between and including two tightly closing shutoff valves and test cocks. 603.3.7 Reduced-Pressure Principle Backflow Prevention Assembly (RP). A reduced-pressure principle backflow prevention assembly consists of two independently acting internally loaded check valves, a differential pressure relief valve, four properly located test cocks, and two isolation valves.

603.3.8 Double Check Detector Fire ProtectionBackflow Prevention Assembly. A double check valve backflow prevention assembly with a parallel detector assembly consisting of a water meter and a double check valve backflow prevention assembly (DC). 603.3.9 Reduced Pressure Detector Fire Protec-tion Backflow Prevention Assembly. A reducedpressure principle backflow prevention assembly with a parallel detector assembly consisting of a water meter and a reduced-pressure principle backflow prevention assembly (RP).