CPC · California Plumbing Code

How do I select the correct backflow prevention device for a given hazard?

Choose the backflow device required by the CPC by (1) determining whether the connection is a low‑hazard (pollution) or high‑hazard (contamination) situation, (2) consulting Table 603.2 to see which devices are permitted for backsiphonage vs backpressure, and (3) applying the specific installation rules in § 603.5.1–§ 603.5.22 (for example, irrigation pumps and chemical injectors require RP assemblies).

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Last reviewed: July 6, 2026

What the code requires — plain English

The California Plumbing Code requires that every cross‑connection be protected by an approved backflow device appropriate to the degree of hazard (pollution — low hazard — or contamination — high hazard). Follow Table 603.2 to match the device to the hazard, and follow the specific application rules in § 603.5.1 through § 603.5.22 for certain fixtures and systems. See § 603.2 for the approval requirement before installation.

The single most important rule: choose the device required by Table 603.2 for the hazard, and follow the specific § 603.5 application rules for that type of equipment or outlet.

Requirements in detail

Start here — a 3‑step decision path grounded in the CPC:

  1. Identify the type of cross‑connection and whether it presents pollution (low hazard) or contamination (high hazard). Refer to the descriptive guidance and examples in § 603.5 subsections.
  2. Use Table 603.2 to determine which device(s) are acceptable for that hazard and whether the concern is backsiphonage or backpressure.
  3. Apply any specific installation rules for that application in § 603.5.1–§ 603.5.22 (critical levels, required device types for pumps/chemicals, air gap requirements, etc.).

Key defined terms (first time used)

  • Backsiphonage — flow caused by negative pressure (see Table 603.2 context).
  • Backpressure — pressure forcing contaminants back into potable system (see Table 603.2 and § 603.5 entries).
  • Critical level — minimum elevation marking for vacuum breakers or devices relative to flood‑rim; required by several § 603.5 rules (example: 6 inches for certain vacuum breakers).

Quick reference table — decision‑relevant dimensions, devices, and code references

Decision factor / value Typical device(s) allowed (short) When to pick Code Reference
Low hazard — backsiphonage Air gap, AVB, Dual check, etc. Simple non‑toxic cross‑connections (see Table 603.2) Table 603.2
Low hazard — backpressure Double check (DC), Dual check where table allows Pressurized non‑contaminating sources Table 603.2
High hazard (contamination) Reduced‑pressure principle (RP) (preferred) Any contamination risk (chemicals, boilers with chemicals, swimming pools, pure water systems) Table 603.2 and § 603.5.18, § 603.5.21
Irrigation without pump or chemicals AVB, PVB, SVB, or RP Typical sprinkler systems without backpressure or injection § 603.5.6
Irrigation with pump (creates backpressure) RP, when device is upstream of pump Pumped systems capable of backpressure § 603.5.6.1
Irrigation with chemical injection RP (chemical injectors require RP) Any chemical injection or provision § 603.5.6.3
Hose outlets (hose bibbs) Nonremovable hose‑bibb backflow preventer, nonremovable hose‑bibb vacuum breaker, or AVB ≥ 6 in above highest usage Potable outlets with hose attachments § 603.5.7
Beverage dispensers (carbonated) Air gap or vented backflow preventer per ASSE 1022 Carbonated beverage machines § 603.5.12
Boilers (steam / hot water) Double check (DC), backflow preventer with intermediate atmospheric vent and PRV, or RP (if chemicals introduced → RP required) Boiler feed connections § 603.5.10
Swimming pools / spas Air gap or RP where submerged fill line or direct connection to circulation system Pools with submerged fill or direct circulation connection § 603.5.21
Pure water process systems (dialysis, semiconductors) RP Protect against backpressure and backsiphonage § 603.5.18
Chemical dispensers ANSI/CAN/ASSE/IAPMO 1055 device or air gap, AVB, PVB, SVB, or RP See § 603.5.22 for options and listing requirements § 603.5.22

Notes: Table 603.2 contains additional device‑specific installation notes (e.g., orientation, minimum clearances, continuous pressure restrictions). Consult Table 603.2 for the exact device allowances for backsiphonage vs backpressure.

Device selection rules pulled from the specific applications (§ 603.5.x)

  • Irrigation / sprinkler systems — if the system has no pumps and no chemical injection, acceptable devices include AVB, PVB, SVB, or RP; if the system has pumps or can develop backpressure, an RP is required when the backflow device is upstream of the source of backpressure (§ 603.5.6 and §§ 603.5.6.1–603.5.6.3).
  • Water supply inlets to tanks, vats, pools — require an air gap or a listed vacuum breaker with critical level ≥ 6 in above overflow rim, or another backflow preventer suitable for the hazard (§ 603.5.5).
  • Beverage machines, lab equipment, steam boilers, pure water systems, chemical dispensers, garbage can washers, pools — each have device/type requirements or options listed in § 603.5.10–§ 603.5.22; these specific rules override broad choices in Table 603.2 for those applications.

Exceptions & special cases

  • The code specifically notes some fire protection system provisions as non‑adopted by the State Fire Marshal; local enforcement/adoption may vary — check § 603.5.14 Note when applying backflow rules to fire systems.
  • Some devices shown in Table 603.2 (for example, certain hose‑connection vacuum breakers or freeze‑resistant wall hydrants) are not for use under continuous pressure conditions — confirm the device listing and intended use before selecting. See Table 603.2 installation notes.
  • Where a specific § 603.5.X entry exists for an application, that specific requirement governs over a generic Table 603.2 allowance for that same application (e.g., chemical injectors always require RP per § 603.5.6.3).

If you need an allowance or installation detail that is not explicitly stated in these controlling sections (for example: required test frequency, exact clearances for every device, or concrete sizing guidance), that information appears elsewhere in the CPC (for example § 603.4 and the manufacturer’s listing) and should be consulted — do not rely on this article alone for those details.

Common mistakes

  • Installing an Atmospheric Vacuum Breaker (AVB) where backpressure can occur (AVBs do not protect against backpressure). Check § 603.5.6 and Table 603.2 before selecting.
  • Using a PVB/SVB or AVB on systems with chemical injection — the CPC requires an RP if chemicals are injected (§ 603.5.6.3).
  • Ignoring critical level requirements for vacuum breakers — several §§ mandate minimum elevations (for example 6 inches in § 603.5.1 and § 603.5.5). Always install to the device’s listing and the applicable § 603.5 rule.
  • Relying on device capability without verifying it is listed/approved for the specific application per § 603.2 and Table 603.2. The Authority Having Jurisdiction must approve devices before installation.

Worked example — concrete scenario

Scenario: You are designing the potable water connection for a single‑family home irrigation system. The system has a booster pump and a fertilizer (chemical) injector.

Step 1 — classify the hazard: chemical injector = contamination (high hazard). (§ 603.5.6.3 requires RP where chemical injectors are present.)

Step 2 — consult the specific irrigation rules: because the system has a pump and an injector, § 603.5.6.1 and § 603.5.6.3 require protection by a reduced‑pressure principle backflow prevention assembly (RP) if the backflow device is located upstream of the source of backpressure; chemical injection also requires an RP.

Conclusion: Select a listed RP assembly sized to the supply main and install per the manufacturer’s instructions and the Authority Having Jurisdiction’s requirements. Do not use an AVB, PVB, or SVB for this installation because they do not provide the level of protection required for chemical injection and pumped/backpressure conditions. (§ 603.5.6.1 & § 603.5.6.3; see Table 603.2 for general device comparison.)

(Notes: This example intentionally focuses on device type selection required by the CPC. Detailed assembly sizing, orientation, precise mounting clearances, testing schedules, and freeze protection are covered in other CPC provisions and manufacturer listings.)

Related provisions (CPC sections to consult)

  • § 603.2 — Approval of devices or assemblies (must be approved/listed before installation).
  • Table 603.2 — Matrix of devices/assemblies and what hazards they protect against (backsiphonage/backpressure, pollution/contamination) — primary selection tool.
  • § 603.5.1 – § 603.5.22 — Specific application rules for fixtures, equipment, irrigation, boilers, beverage dispensers, pools, chemical dispensers, pure water systems, etc. (use these to override or refine Table 603.2 choices).
  • (If needed for installation details) see the CPC sections on device construction/listings and installation requirements referenced within Table 603.2 and § 603.5 entries.

Code references

Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:

  • CPC § 603.5.6.1 High relevance — show source text

    (1) Atmospheric vacuum breaker (AVB)

    (2) Pressure vacuum breaker backflow prevention assembly (PVB)

    (3) Spill-resistant pressure vacuum breaker (SVB)

    (4) Reduced-pressure principle backflow prevention assembly (RP)

    (5) A valve complying with IAPMO PS 72 603.5.6.1 Systems with Pumps. Where sprinkler and irrigation systems have pumps, connections for pumping equipment, or auxiliary air tanks, or are otherwise capable of creating backpressure, the potable water supply shall be protected by the following type of device where the backflow device is located upstream from the source of backpressure:

    (1) Reduced-pressure principle backflow prevention assembly (RP) 603.5.6.2 Systems with Backflow Devices. Where systems have a backflow device installed downstream from a potable water supply pump or a potable water supply pump connection, the device shall be one of the following:

    (1) Atmospheric vacuum breaker (AVB)

    (2) Pressure vacuum breaker backflow prevention assembly (PVB)

    (3) Spill-resistant pressure vacuum breaker (SVB)

    (4) Reduced-pressure principle backflow prevention assembly (RP) 603.5.6.3 Systems with Chemical Injectors. Where systems include a chemical injector or provisions for chemical injection, the potable water supply shall be protected by a reduced-pressure principle backflow prevention assembly (RP).

    2025 CALIFORNIA PLUMBING CODE 141

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    WATER SUPPLY AND DISTRIBUTION

    TABLE 603.2 BACKFLOW PREVENTION DEVICES, ASSEMBLIES, AND METHODS Col2 Col3 Col4 Col5 Col6 Col7
    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,
  • CPC § 25.4 High relevance — show source text

    2 Vertical walls, ribs, or similar obstructions extending from the water surface to or above the horizontal plane of the spout opening other than specified in Footnote 1 above. The effect of three or more such vertical walls or ribs has not been determined. In such cases, the air gap shall be measured from the top of the wall. 3 The effective opening shall be the minimum cross-sectional area at the seat of the control valve or the supply pipe or tubing that feeds the device or outlet. Where two or more lines supply one outlet, the effective opening shall be the sum of the cross-sectional areas of the individual supply lines or the area of the single outlet, whichever is smaller. 4 Air gaps less than 1 inch (25.4 mm) shall be approved as a permanent part of a listed assembly that has been tested under actual backflow conditions with vacuums of 0 to 25 inches of mercury (85 kPa).

    603.5.7 Outlets with Hose Attachments. Potable water outlets with hose attachments, other than water heater drains, boiler drains, and clothes washer connections, shall be protected by a nonremovable hose bibbtype backflow preventer, a nonremovable hose bibb-type vacuum breaker, or by an atmospheric vacuum breaker installed not less than 6 inches (152 mm) above the highest point of usage located on the discharge side of the last valve. In climates where freezing temperatures occur, a listed self-draining frost-proof hose bibb with an integral backflow preventer or vacuum breaker shall be used. 603.5.8 Water-Cooled Equipment. Water-cooled compressors, degreasers, or other water-cooled equipment shall be protected by a backflow preventer installed in accordance with the requirements of this chapter. Water-cooled equipment that produces backpressure shall be equipped with the appropriate protection. 603.5.9 Aspirators. Water inlets to water-supplied aspirators shall be equipped with a vacuum breaker installed in accordance with its listing requirements and this chapter. The discharge shall drain through an air gap. Where the tailpiece of a fixture to receive the discharge of an aspirator is used, the air gap shall be located above the flood-level rim of the fixture.

    603.5.10 Steam or Hot Water Boilers. Potable water connections to steam or hot water boilers shall be protected from backflow by a double check valve backflow prevention assembly, backflow preventer with intermediate atmospheric vent and pressure reducing valve, or reduced pressure principle backflow prevention assembly in accordance with Table 603.2. Where chemicals are introduced into the system a reduced pressure principle backflow prevention assembly shall be provided in accordance with Table 603.2.

    603.5.11 Nonpotable Water Piping. In cases where it is impractical to correct individual cross-connections on the domestic waterline, the line supplying such outlets

    shall be considered a nonpotable water line. No drinking or domestic water outlets shall be connected to the nonpotable waterline. Where possible, portions of the nonpotable waterline shall be exposed, and exposed portions shall be properly identified in a manner satisfactory to the Authority Having Jurisdiction. Each outlet on the nonpotable waterline that is permitted to be used for drinking or domestic purposes shall be posted: “CAUTION: NONPOTABLE WATER, DO NOT DRINK.”

    [HCD 1 & HCD 2] An international symbol of a glass in a circle with a slash through it shall be provided sim- ilar to that shown in Figure 601.

  • CPC § 603.5.9 High relevance — show source text

    603.5.9 Aspirators. Water inlets to water-supplied aspirators shall be equipped with a vacuum breaker installed in accordance with its listing requirements and this chapter. The discharge shall drain through an air gap. Where the tailpiece of a fixture to receive the discharge of an aspirator is used, the air gap shall be located above the flood-level rim of the fixture.

    603.5.10 Steam or Hot Water Boilers. Potable water connections to steam or hot water boilers shall be protected from backflow by a double check valve backflow prevention assembly, backflow preventer with intermediate atmospheric vent and pressure reducing valve, or reduced pressure principle backflow prevention assembly in accordance with Table 603.2. Where chemicals are introduced into the system a reduced pressure principle backflow prevention assembly shall be provided in accordance with Table 603.2.

    603.5.11 Nonpotable Water Piping. In cases where it is impractical to correct individual cross-connections on the domestic waterline, the line supplying such outlets

    shall be considered a nonpotable water line. No drinking or domestic water outlets shall be connected to the nonpotable waterline. Where possible, portions of the nonpotable waterline shall be exposed, and exposed portions shall be properly identified in a manner satisfactory to the Authority Having Jurisdiction. Each outlet on the nonpotable waterline that is permitted to be used for drinking or domestic purposes shall be posted: “CAUTION: NONPOTABLE WATER, DO NOT DRINK.”

    [HCD 1 & HCD 2] An international symbol of a glass in a circle with a slash through it shall be provided sim- ilar to that shown in Figure 601.

    603.5.12 Beverage Dispensers. Potable water supply to carbonated beverage dispensers shall be protected by an air gap or a vented backflow preventer that complies with ASSE 1022. For carbonated beverage dispensers, piping material installed downstream of the backflow preventer shall not be affected by carbon dioxide gas. Non-carbonated beverage dispensers, such as ice makers and coffee machines, shall be protected by an air gap or dual check backflow preventer that comply with ASSE 1032 or ASSE 1024.

    603.5.13 Deck-Mounted and Equipment- Mounted Vacuum Breakers. Deck-mounted or equipment-mounted vacuum breakers shall be installed in accordance with their listing and the manufacturer’s installation instructions, with the critical level not less than 1 inch (25.4 mm) above the flood-level rim.

    603.5.14 Protection from Fire Systems.

    Note: Fire Protection Systems has not been adopted by the State Fire Marshal. This section cannot be adopted or enforced pursuant to California Health and Safety Code 13114.7(a), which is being cited for reference. California Health and Safety Code 13114.7.

    (a) For the purposes of this section the following are definitions of class I and class II systems:

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    WATER SUPPLY AND DISTRIBUTION

  • CPC § 603.2 High relevance — show source text

    | |Chemical dispenser with
    integral backflow protec-
    tion|ANSI/CAN/
    ASSE/IAPMO
    1055|X|––|X|––|Shall be installed in accordance with
    manufacturer’s installation instructions with
    dedicated water supply whenever possible.| |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| |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.|

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    WATER SUPPLY AND DISTRIBUTION

    TABLE 603.2 BACKFLOW PREVENTION DEVICES, ASSEMBLIES, AND METHODS (continued) Col2 Col3 Col4 Col5 Col6 Col7
    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.
  • CPC § 602.4 High relevance — show source text

    602.4 Approval by Authority. No water piping supplied by a private water supply system shall be connected to any other source of supply without the approval of the Authority Having Jurisdiction, Health Department, or other department having jurisdiction.

    603.0 Cross-Connection Control.

    603.1 General. Cross-connection control shall be provided in accordance with the provisions of this chapter.

    No person shall install a water-operated equipment or mechanism, or use a water-treating chemical or substance, where it is found that such equipment, mechanism, chemical, or substance causes pollution or contamination of the domestic water supply. Such equipment or mechanism shall be permitted where equipped with an approved backflow prevention device or assembly.

    603.2 Approval of Devices or Assemblies. Before a 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 603.5.22.

    2025 CALIFORNIA PLUMBING CODE 139

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    WATER SUPPLY AND DISTRIBUTION

    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 certified in accordance with ASSE/IAPMO/ANSI Series 5000 or any other additional certification approved by the Authority Having Jurisdiction.

    603.3 Backflow Prevention Devices, Assemblies, and Methods. Backflow prevention devices, assemblies, and methods shall comply with Section 603.3.1 through Section 603.3.12.

    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.

  • CPC § 603.5.2 High relevance — show source text

    603.5.2 Ballcock. Water closet and urinal tanks shall be equipped with a ballcock. The ballcock shall be installed with the critical level not less than 1 inch (25.4 mm) above the full opening of the overflow pipe. In cases where the ballcock has no hush tube, the bottom of the water supply inlet shall be installed 1 inch (25.4 mm) above the full opening of the overflow pipe.

    603.5.3 Backflow Prevention. Water closet flushometer tanks shall be protected against backflow by an approved backflow prevention assembly, device, or method.

    603.5.4 Heat Exchangers. Heat exchangers used for heat transfer, heat recovery, or solar heating shall protect the potable water system from being contaminated by the

    heat-transfer medium. Single-wall heat exchangers used in indirect-fired water heaters shall meet the requirements of Section 505.4.1. Double-wall heat exchangers shall separate the potable water from the heat-transfer medium by providing a space between the two walls that are vented to the atmosphere. 603.5.5 Water Supply Inlets. Water supply inlets to tanks, vats, sumps, swimming pools, and other receptors shall be protected by one of the following means:

    (1) An approved air gap.

    (2) A listed vacuum breaker installed on the discharge side of the last valve with the critical level not less than 6 inches (152 mm) or in accordance with its listing.

    (3) A backflow preventer suitable for the degree of hazard, installed in accordance with the requirements for that type of device or assembly as set forth in this chapter. 603.5.6 Protection from Lawn Sprinklers and Irri- gation Systems. Potable water supplies to systems having no pumps or connections for pumping equipment, and no chemical injection or provisions for chemical injection, shall be protected from backflow by one of the following devices:

    (1) Atmospheric vacuum breaker (AVB)

    (2) Pressure vacuum breaker backflow prevention assembly (PVB)

    (3) Spill-resistant pressure vacuum breaker (SVB)

    (4) Reduced-pressure principle backflow prevention assembly (RP)

    (5) A valve complying with IAPMO PS 72 603.5.6.1 Systems with Pumps. Where sprinkler and irrigation systems have pumps, connections for pumping equipment, or auxiliary air tanks, or are otherwise capable of creating backpressure, the potable water supply shall be protected by the following type of device where the backflow device is located upstream from the source of backpressure:

    (1) Reduced-pressure principle backflow prevention assembly (RP) 603.5.6.2 Systems with Backflow Devices. Where systems have a backflow device installed downstream from a potable water supply pump or a potable water supply pump connection, the device shall be one of the following:

    (1) Atmospheric vacuum breaker (AVB)

    (2) Pressure vacuum breaker backflow prevention assembly (PVB)

    (3) Spill-resistant pressure vacuum breaker (SVB)

    (4) Reduced-pressure principle backflow prevention assembly (RP) 603.5.6.3 Systems with Chemical Injectors. Where systems include a chemical injector or provisions for chemical injection, the potable water supply shall be protected by a reduced-pressure principle backflow prevention assembly (RP).

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  • CPC § 5.1 High relevance — show source text
    2 BACKFLOW PREVENTION DEVICES, ASSEMBLIES, AND METHODS (continued) Col2 Col3 Col4 Col5 Col6 Col7
    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 man-
    ufacturer’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.
    Freeze resistant sanitary
    yard hydrants    		 ASSE 1057 X –– X –– Such devices are not for use under
    continuous pressure conditions.4
    Hose connection back-
    flow preventers    		 ASSE 1052 X –– X –– Such devices are not for use under
    continuous pressure conditions.4,6
    Hose connection vac-
    uum breakers    		 ASSE 1011 X –– X –– Such devices are not for use under continuous
    pressure conditions. No valve downstream.4,6
    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
    Pressure Vacuum Breaker
    Backflow Prevention
    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.
  • CPC § 603.5.14.2 High relevance — show source text

    (1) Reduced pressure principle backflow prevention assembly (RP)

    (2) Reduced pressure detector fire protection backflow prevention assembly

    Nonpotable water sources include fire department vehicles carrying water of questionable quality or water that is treated with antifreeze, corrosion inhibitors, or extinguishing agents. 603.5.14.2 Chemicals. Where antifreeze, corrosion inhibitors, or other chemicals are added to a fire protection system supplied from a potable water supply, the potable water system shall be protected by one of the following:

    (1) Reduced pressure principle backflow prevention assembly (RP)

    (2) Reduced pressure detector fire protection backflow prevention assembly 603.5.14.3 Hydraulic Design. Where a backflow device is installed in the potable water supply to a fire protection system, the hydraulic design of the system shall account for the pressure drop through the backflow device. Where such devices are retrofitted for an existing fire protection system, the hydraulics of the sprinkler system design shall be checked to verify that there will be sufficient water pressure available for satisfactory operation of the fire sprinklers. 603.5.15 Health Care or Laboratory Areas. Vacuum breakers for washer-hose bedpans shall be located not less than 5 feet (1524 mm) above the floor. Hose con

    nections in health care or laboratory areas shall be not less than 6 feet (1829 mm) above the floor. 603.5.16 Special Equipment. Portable cleaning equipment and dental vacuum pumps shall be protected from backflow by an air gap, an atmospheric vacuum breaker, a spill-resistant vacuum breaker, or a reduced pressure principle backflow preventer.

    603.5.17 Potable Water Outlets and Valves. Potable water outlets, freeze-proof yard hydrants, combination stop-and-waste valves, or other fixtures that incorporate a stop and waste feature that drains into the ground shall not be installed underground. 603.5.18 Pure Water Process Systems. The water supply to a pure water process system, such as dialysis water systems, semiconductor washing systems, and similar process piping systems, shall be protected from backpressure and backsiphonage by a reduced-pressure principle backflow preventer. 603.5.18.1 Dialysis Water Systems. The individual connections of the dialysis related equipment to the dialysis pure water system shall not require additional backflow protection. 603.5.19 Garbage Can Washers. Where garbage can washers are connected to a potable water supply system, the connection shall be protected against backflow in accordance with Table 603.2.

    603.5.20 Plumbing Fixture Fittings. Plumbing fixture fittings with integral backflow protection shall comply with ASME A112.18.1/CSA B125.1. 603.5.21 Swimming Pools, Spas, and Hot Tubs. Potable water supply to swimming pools, spas, and hot tubs shall be protected by an air gap or a reduced pressure principle backflow preventer in accordance with the following:

    (1) The unit is equipped with a submerged fill line.

    (2) The potable water supply is directly connected to the unit circulation system. 603.5.22 Chemical Dispensers. The water supply to chemical dispensers shall be protected against backflow by one of the following:

  • CPC § 603.3 High relevance — show source text

    Testing or maintenance shall be performed by a certified backflow assembly tester or repairer certified in accordance with ASSE/IAPMO/ANSI Series 5000 or any other additional certification approved by the Authority Having Jurisdiction.

    603.3 Backflow Prevention Devices, Assemblies, and Methods. Backflow prevention devices, assemblies, and methods shall comply with Section 603.3.1 through Section 603.3.12.

    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 force loaded 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 Protection Backflow 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).

    603.3.10 Dual Check Backflow Preventer. A dual check backflow preventer consists of two independently acting check valves, force loaded to a normally closed position.

    603.3.11 Laboratory Faucet Backflow Preven- ters. Laboratory faucet backflow preventers shall comply with ASSE 1035.

    603.3.12 Backflow Preventer with Intermediate Atmospheric Vent. A backflow preventer with intermediate atmospheric vent consists of two independently acting check valves, force loaded to a normally closed position, and an intermediate chamber with a means for automatically venting to atmosphere, force loaded to a normally open position. 603.4 General Requirements. Assemblies shall comply with listed standards and be acceptable to the Authority Having Jurisdiction, with jurisdiction over the selection and installation of backflow prevention assemblies.

    **603.4.1 Backflow Prevention Valve.

  • CPC § 601.8.1.1 Medium relevance — show source text

    601.8.1.1 Equipment using potable water shall be so installed as to prevent back-siphonage into the potable water system.

    601.8.1.2 Non-potable water is permitted only in those parts of o ffi cial plants where no edible product is han- dled or prepared, and then only for limited purposes, such as on ammonia condensers not connected with the potable water supply, in vapor lines serving inedi- ble product rendering tanks, in connection with equip- ment used for washing and washing inedible products preparatory to tanking, and in sewer lines for moving heavy solids in sewage. In all cases, non-potable water lines shall be clearly identi fi ed and shall not be cross connected with the potable water supply.

    Exception: Cross connection is permitted if this is necessary for fi re protection, and such connection is of a type with a break to ensure against accidental contamination, and is approved by local authorities or by the Department.

    601.8.2 All pipelines, reservoirs, tanks, cooling towers, and like equipment employed in handling reused water shall be constructed and installed so as to facilitate their cleaning and inspection.

    601.8.3 Hot water for cleaning rooms and equipment shall be delivered under pressure to outlets and shall be of such temperature as to accomplish a thorough cleanup.

    601.8.3.1 An ample supply of water at not less than 180°F (82°C) shall be available when used for san- itizing purposes.

    601.8.4 Pens, alleys, and runways shall have hose con- nections for cleanups purposes.

    602.0 Unlawful Connections.

    602.1 Prohibited Installation. No installation of potable water supply piping, or part thereof, shall be made in such a manner that it will be possible for used, unclean, polluted, or contaminated water, mixtures, or substances to enter a portion of such piping from a tank, receptor, equipment, or plumbing fixture by reason of backsiphonage, suction, or other cause, either during normal use and operation thereof, or where such tank, receptor, equipment, or plumbing fixture is flooded or subject to pressure exceeding the operating pressure in the hot or cold water piping. 602.2 Cross-Contamination. No person shall make a connection or allow one to exist between pipes or conduits carrying domestic water supplied by a public or private building supply system, and pipes, conduits, or fixtures containing or carrying water from any other source or containing or carrying water that has been used for any purpose whatsoever, or piping carrying chemicals, liquids, gases, or substances whatsoever, unless there is provided a backflow prevention device approved for the potential hazard and maintained in accordance with this code. Each point of use shall be separately protected where potential cross-contamination of individual units exists.

    602.3 Backflow Prevention. No plumbing fixture, device, or construction shall be installed or maintained, or shall be connected to a domestic water supply, where such installation or connection provides a possibility of polluting such water supply or cross-connection between a distributing system of water for drinking and domestic purposes and water that becomes contaminated by such plumbing fixture, device, or construction unless there is provided a backflow prevention device approved for the potential hazard.

  • CPC § 603.3.7 Medium relevance — show source text

    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 Protection Backflow 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).

    603.3.10 Dual Check Backflow Preventer. A dual check backflow preventer consists of two independently acting check valves, force loaded to a normally closed position.

    603.3.11 Laboratory Faucet Backflow Preven- ters. Laboratory faucet backflow preventers shall comply with ASSE 1035.

    603.3.12 Backflow Preventer with Intermediate Atmospheric Vent. A backflow preventer with intermediate atmospheric vent consists of two independently acting check valves, force loaded to a normally closed position, and an intermediate chamber with a means for automatically venting to atmosphere, force loaded to a normally open position. 603.4 General Requirements. Assemblies shall comply with listed standards and be acceptable to the Authority Having Jurisdiction, with jurisdiction over the selection and installation of backflow prevention assemblies.

    603.4.1 Backflow Prevention Valve. Where more than one backflow prevention valve is installed on a single premise, and the valves are installed in one location, each separate valve shall be permanently identified by the permittee in a manner satisfactory to the Authority Having Jurisdiction. 603.4.2 Testing. The premise owner or responsible person shall have the backflow prevention assembly tested by a certified backflow assembly tester 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. The periodic testing shall be performed in accordance with the procedures referenced in ASSE/IAPMO/ANSI Series 5000 by a tester qualified in accordance with those standards. The field test kit used shall comply with ASSE 1064.

    603.4.3 Access and Clearance. Access and clearance shall be provided for the required testing, maintenance, and repair. Access and clearance shall be in accordance with the manufacturer’s instructions, and not less than 12 inches (305 mm) between the lowest portion of the assembly and grade, floor, or platform. Installations elevated that exceed 5 feet (1524 mm) above the floor or grade shall be provided with a platform capable of supporting a tester or maintenance person.

    603.4.4 Connections. Direct connections between potable water piping and sewer-connected wastes shall not be permitted to exist un der any condition with or without backflow protection. Where potable water is discharged to the drainage system, it shall be by means of an approved air gap of two pipe diameters of the supply

    140 2025 CALIFORNIA PLUMBING CODE

    ), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

    WATER SUPPLY AND DISTRIBUTION

  • CPC § 16-2021 Medium relevance — show source text

    16-2021|Personal Hygiene Devices for Water Closets|Fixtures|411.4| |CSA B64.1.1-2021|Atmospheric Vacuum Breakers (AVB)|Backflow Protection|Table 603.2| |CSA B64.1.2-2021|Pressure Vacuum Breakers (PVB)|Backflow Protection|Table 603.2| |CSA B64.2.1.1-2021|Hose Connection Dual Check Vacuum Breakers (HCDVB)|Backflow Protection|Table 603.2| |CSA B64.4-2021|Reduced Pressure Principle (RP) Backflow Preventers|Backflow Protection|Table 603.2| |CSA B64.4.1-2021|Reduced Pressure Principle Backflow Preventers for Fire Pro-
    tection Systems (RPF)|Backflow Protection|Table 603.2| |CSA B64.5-2021|Double Check Valve (DCVA) Backflow Preventers|Backflow Protection|Table 603.2| |CSA B64.5.1-2021|Double Check Valve Backflow Preventers for Fire Protection
    Systems (DCVAF)|Backflow Protection|Table 603.2| |CSA B79-2008 (R2018)|Commercial and Residential Drains and Cleanouts|Fixtures|418.1, Table 707.2| |ASME A112.18.1-
    2018/CSA B125.1-2018|Plumbing Supply Fittings|Fittings|408.4, 417.1, 417.2,
    417.3, 417.4, 417.6,
    603.5.20| |ASME A112.18.2-
    2020/CSA B125.2-2020|Plumbing Waste Fittings|Fittings|404.1, 408.5| |CSA B125.3-2018|Plumbing Fittings|Fittings|409.4(1), 410.3(1)| |CSA B125.5-2011/IAPMO
    Z600-2011 (R2016)|Flexible Water Connectors with Excess Flow Shut-off Device|Miscellaneous|604.5| |ASME A112.18.6-
    2017/CSA B125.6-2017
    (R2021)|Flexible Water Connectors|Piping|604.5, 604.13| |ASSE 1002-2020/ASME
    A112.1002-2020/CSA
    B125.12-2020|Anti-Siphon Fill Valves for Water Closet Tanks|Backflow Protection|413.3, Table 603.2| |ASME A112.4.14-
    2017/CSA B125.14-2017|Manually Operated Valves for Use in Plumbing Systems|Valves|606.1| |ASSE 1016-2017/ASME
    A112.1016-2017/CSA
    B125.16-2017|Automatic Compensating Valves for Individual Showers and
    Tub/Shower Combinations|Valves|408.4, 408.4.2(1)| |ASSE 1037-2020/ASME
    A112.1037-2020/CSA
    B125.37-2020|Pressurized Flushing Devices for Plumbing Fixtures|Backflow Protection|413.2| |ASSE 1070-2020/ASME
    A112.

Frequently asked questions

What is the first thing I should check when selecting a backflow device?

Confirm whether the connection poses pollution (low hazard) or contamination (high hazard) and then consult Table 603.2 to see which devices are allowed for that type of hazard.

If I have a pump on my irrigation system, can I use a PVB?

If the pump or connections can create backpressure, an RP is required when the backflow device is upstream of the source of backpressure; otherwise § 603.5.6.2 lists AVB/PVB/SVB/RP as options if the backflow device is installed downstream of the pump. Check the exact system layout against § 603.5.6.1–603.5.6.2.

Do I always need a reduced‑pressure (RP) assembly for chemicals?

Yes — where systems include a chemical injector or provisions for chemical injection, the potable water supply must be protected by an RP (see § 603.5.6.3).

Can I use an atmospheric vacuum breaker (AVB) for a hose bibb?

You may use a listed nonremovable hose‑bibb backflow preventer, a nonremovable hose‑bibb vacuum breaker, or an AVB installed not less than 6 inches above the highest point of usage, per § 603.5.7. Confirm device listing and freeze‑protection if applicable.

Where do I find the device installation orientation/clearance notes?

Table 603.2 includes installation notes (orientation, minimum elevations for some devices, and continuous‑pressure limitations). Always review the Table entry for the chosen device and the device listing.

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