Skip to content
ChatProjectCodes

Earlier editions: 20222019

Chapter 6 — WATER SUPPLY AND DISTRIBUTION

603.4 General Requirements.

California Plumbing Code (Title 24, Part 5) · 2025 edition · updated 2026-09-12 · California

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

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

WATER SUPPLY AND DISTRIBUTION

inlet, but in no case shall the gap be less than 1 inch (25.4 mm). Connection shall be permitted to be made to the inlet side of a trap provided that an approved vacuum breaker is installed not less than 6 inches (152 mm), or the distance according to the device’s listing, above the flood-level rim of such trapped fixture, so that at no time will such device be subjected to backpressure.

603.4.5 Hot Water Backflow Preventers. Backflow preventers for hot water exceeding 110°F (43°C) shall be a type designed to operate at temperatures exceeding 110°F (43°C) without rendering a portion of the assembly inoperative. 603.4.6 Integral Backflow Preventers. Fixtures, appliances, or appurtenances with integral backflow preventers or integral air gaps manufactured as a unit shall be installed in accordance with their listing requirements and the manufacturer’s installation instructions.

be a type designed to operate at temperatures exceeding 110°F (43°C) without rendering a portion of the assembly inoperative. 603.4.6 Integral Backflow Preventers. Fixtures, appliances, or appurtenances with integral backflow preventers or integral air gaps manufactured as a unit shall be installed in accordance with their listing requirements and the manufacturer’s installation instructions.

603.4.7 Freeze Protection. In cold climate areas, backflow assemblies and devices shall be protected from freezing with an outdoor enclosure that complies with ASSE 1060 or by a method acceptable to the Authority Having Jurisdiction. 603.4.8 Drain Lines. Drain lines serving backflow devices or assemblies shall be sized in accordance with the discharge rates of the manufacturer’s flow charts of such devices or assemblies.

603.4.9 Prohibited Locations. Backflow prevention devices with atmospheric vents or ports shall not be installed in pits, underground, or submerged locations. Backflow preventers shall not be located in an area containing fumes that are toxic, poisonous, or corrosive.

Get a plain-English answer with a citation back to this text.

Ask AI about this code
Export this section
▸Contents — California Plumbing Code (Title 24, Part 5)
California Plumbing Code (Title 24, Part 5)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — PLUMBING FIXTURES AND FIXTURE FITTINGS
  5. Chapter 5 — WATER HEATERS
  6. ▸Chapter 6 — WATER SUPPLY AND DISTRIBUTION
    Overview
    1. 601.1 Applicability.
    2. 601.2 Water Supply and Flushing.
    3. 601.3 Identification of a Potable and Nonpotable Water System.
    4. 601.4 Schools of Cosmetology and Cosmetological
    5. 601.5 Meat and Poultry Processing Plants.
    6. 601.6 Collection Centers and Facilities. [AGR]
    7. 601.7 Renderers. [AGR]
    8. 601.8 Horse Meat and Pet Food Establishments. [AGR]
    9. 602.1 Prohibited Installation.
    10. 602.2 Cross-Contamination.
    11. 602.3 Backflow Prevention.
    12. 602.4 Approval by Authority.
    13. 603.1 General.
    14. 603.2 Approval of Devices or Assemblies.
    15. 603.3 Backflow Prevention Devices, Assemblies, and Methods.
    16. 603.4 General Requirements.
    17. 603.5 Specific Requirements.
    18. 604.1 Pipe, Tube, and Fittings.
    19. 604.2 Lead Content.
    20. 604.3 Copper or Copper Alloy Tube.
    21. 604.4 Hard-Drawn Copper or Copper Alloy Tubing.
    22. 604.5 Flexible Connectors.
    23. 604.6 Cast-Iron Fittings.
    24. 604.7 Malleable Iron Fittings.
    25. 604.8 Previously Used Piping and Tubing.
    26. 604.9 Epoxy Coating.
    27. 604.10 Plastic Materials.
    28. 604.11 Solder.
    29. 604.12 Flexible Corrugated Connectors.
    30. 604.13 Water Heater Connectors.
    31. 605.1 Copper or Copper Alloy Pipe, Tubing,
    32. 605.2 CPVC Plastic Pipe and Joints.
    33. 605.3 CPVC/AL/CPVC Plastic Pipe and Joints.
    34. 605.4 Ductile Iron Pipe and Joints.
    35. 605.5 Galvanized Steel Pipe and Joints.
    36. 605.6 PE
    37. 605.7 PE-AL-PE Plastic
    38. 605.8 PE-RT.
    39. 605.9 PEX
    40. 605.10 PEX-AL-PEX Plastic Tubing and Joints.
    41. 605.11 Polypropylene (PP) Piping and Joints.
    42. 605.12 PVC
    43. 605.13 Stainless Steel Pipe
    44. 605.14 Slip Joints.
    45. 605.15 Dielectric Unions.
    46. 605.16 Joints Between Various Materials.
    47. 606.1 General.
    48. 606.2 Fullway Valve.
    49. 606.3 Multidwelling Units.
    50. 606.4 Multiple Openings.
    51. 606.5 Control Valve.
    52. 606.6 Accessible.
    53. 606.7 Multiple Fixtures.
    54. 606.8 [OSHPD 1, 1R, 2, 3, 4 & 5]
    55. 606.9 Check Valve Required.
    56. 606.10 Leak Detection Devices.
    57. 607.1 General.
    58. 607.2 Private Well Water Tanks.
    59. 607.3 Potable Water Tanks.
    60. 607.4 Venting.
    61. 607.5 Overflow.
    62. 607.6 Valves.
    63. 608.1 Inadequate Water Pressure.
    64. 608.2 Excessive Water Pressure.
    65. 608.3 Expansion Tanks, and Combination Tempera-ture and Pressu…
    66. 608.4 Pressure Relief Valves.
    67. 608.5 Discharge Piping.
    68. 608.6 Water-Heating Devices.
    69. 608.7 Vacuum Relief Valves.
    70. 609.1 Installation.
    71. 609.2 Trenches.
    72. 609.3 Under Concrete Slab.
    73. 609.4 Testing.
    74. 609.5 Unions.
    75. 609.6 Location.
    76. 609.7 Abutting Lot.
    77. 609.8 Pumps.
    78. 609.9 Low-Pressure Cutoff Required on Booster Pumps for Water …
    79. 609.10 Disinfection of Potable Water System.
    80. 609.11 Water Hammer.
    81. 609.12 Pipe Insulation.
    82. 610.1 Size.
    83. 610.2 Pressure Loss.
    84. 610.3 Quantity of Water.
    85. 610.4 Sizing Water Supply and Distribution Systems.
    86. 610.5 Sizing per Appendices A, C,
    87. 610.6 Friction and Pressure Loss.
    88. 610.7 Conditions for Using Table 610.4.
    89. 610.8 Size of Meter and Building Supply Pipe Using Table 610.4.
    90. 610.9 Size of Branches.
    91. 610.10 Sizing for Flushometer Valves.
    92. 610.11 Sizing Systems for Flushometer Tanks.
    93. 610.12 Sizing for Velocity.
    94. 610.13 Exceptions.
    95. 611.1 Application.
    96. 611.2 Air Gap Discharge.
    97. 611.3 Connection Tubing.
    98. 611.4 Sizing of Residential Softeners.
    99. 612.1 Installation.
    100. 613.1 The domestic water-heating equipment and distribu-
    101. 613.2 At least two pieces of hot-water-heating equipment shall
    102. 613.3 Instantaneous heaters are permitted for supplying hot
    103. 613.4 Water storage tanks shall be fabricated of corrosion-
    104. 613.5 Temperature control valves shall be provided to auto-
    105. 613.6 Hot-water distribution system serving patient care areas
    106. 613.7 At fixtures where water exceeding 125°F (52°C) is acces-
    107. 613.8 Sectionalizing valves shall be provided as required by S…
    108. 613.9 Hot water distribution shall include test ports and valved
    109. 614.1 Dialysis water feedlines shall be CPVC (chlorinated
    110. 614.2 All piping for multistation or central dialysis units sh…
    111. 614.3 All valves shall be located in accessible locations.
    112. 614.4 Piping and valves shall be identified according to their…
    113. 614.5 A means of preventing backwashing or flushing of the
    114. 614.6 A continuous audible alarm shall sound at the nurses’
    115. 614.7 Water treatment equipment and water used for dialysis
    116. 614.8 A diagram of all piping as installed shall be posted at …
    117. 615.1 Uses Not Permitted.
    118. 615.2 [OSHPD 1, 1R, 2, 3, 4 & 5]
    119. 615.3 [OSHPD 1, 1R, 2, 3, 4 & 5]
    120. 616.1 For new acute care hospital buildings submitted after
    121. 616.2 The emergency supply of water shall be provided at ade-
    122. 616.3 Storage tank connections and circulation shall be
  7. Chapter 7 — SANITARY DRAINAGE
  8. Chapter 8 — INDIRECT WASTES
  9. Chapter 9 — VENTS
  10. Chapter 10 — TRAPS AND INTERCEPTORS
  11. Chapter 11 — STORM DRAINAGE
  12. Chapter 12 — FUEL GAS PIPING
  13. Chapter 13 — HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICA…
  14. Chapter 14 — FIRESTOP PROTECTION
  15. Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
  16. Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS
  17. Chapter 17 — REFERENCED STANDARDS
  18. Appendix A — RECOMMENDED RULES FOR SIZING THE WATER SUPPLY SYS…
  19. Appendix B — EXPLANATORY NOTES ON COMBINATION WASTE AND VENT S…
  20. Appendix C — ALTERNATE PLUMBING SYSTEMS
  21. Appendix D — SIZING STORM WATER DRAINAGE SYSTEMS
  22. Appendix E — MANUFACTURED/MOBILE HOME PARKS AND RECREATIONAL V…
  23. Appendix F — FIREFIGHTER BREATHING AIR REPLENISHMENT SYSTEMS
  24. Appendix G — SIZING OF VENTING SYSTEMS
  25. Appendix H — PRIVATE SEWAGE DISPOSAL SYSTEMS
  26. Appendix I — INSTALLATION STANDARDS
  27. Appendix J — COMBINATION OF INDOOR AND OUTDOOR COMBUSTION AND …
  28. Appendix K — POTABLE RAINWATER CATCHMENT SYSTEMS
  29. Appendix L — SUSTAINABLE PRACTICES
  30. Appendix M — PEAK WATER DEMAND CALCULATOR
  31. Appendix N — IMPACT OF WATER TEMPERATURE ON THE POTENTIAL FOR …
  32. Appendix O — NON-SEWERED SANITATION SYSTEMS
  33. Appendix P — PROFESSIONAL QUALIFICATIONS
  34. Appendix Q — INDOOR HORTICULTURAL FACILITIES
  35. Appendix R — TINY HOUSES
  36. Appendix S — ONSITE STORMWATER TREATMENT SYSTEMS

GoCodebook provides public access, search, citation, multilingual explanation, and practical interpretation of legally adopted building regulations. It is not a substitute for the official ICC or California code publications.