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Chapter 3 — GENERAL REGULATIONS

314.4 Excavations.

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.

Excavations shall be completely backfilled as soon after inspection as practicable. Precaution shall be taken to ensure compactness of backfill around piping without damage to such piping. Trenches shall be backfilled in thin layers to 12 inches (305 mm) above the top of the piping with clean earth, which shall not contain stones, boulders, cinder fill, frozen earth, construction debris, or other materials that will damage or break the piping or cause corrosive action. Mechanical devices such as bulldozers, graders, etc., shall be permitted to be then used to complete backfill to grade. Fill shall be properly compacted. Precautions shall be taken to ensure permanent stability for pipe laid in filled or made ground.

Underground thermoplastic pipe and fittings for sewers and other gravity flow applications shall be installed in accordance with this code and Section 314.4.1.

314.4.1 Installation of Thermoplastic Pipe and Fittings. Trench width for thermoplastic sewer pipe shall be not less than 1.25 times the outside diameter of the piping plus 12 inches (305 mm) or the outside diameter of the piping plus not less than 16 inches (406 mm). Thermoplastic piping shall be bedded in not less than 4 inches (102 mm) of granular fill supporting the piping. The backfill for thermoplastic piping shall be compacted along the sides of the piping in 6 inch (152 mm) layers and continue to not less than 12 inches (305 mm) above the piping. Compaction shall be not less than an 85 percent standard proctor density.

TABLE 313.6
HANGER ROD SIZES HANGER ROD SIZES
PIPE AND TUBE SIZE
(inches)		 ROD SIZE
(inches)
1⁄2 – 4 3⁄8
5 – 8 1⁄2
10 – 12 5⁄8

For SI units: 1 inch = 25.4 mm

2022 CALIFORNIA PLUMBING CODE 53

GENERAL REGULATIONS

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▸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
    Overview
    1. 301.1 Applicability. This chapter shall govern the general
    2. 301.2 Minimum Standards. Pipe, pipe fittings, traps, fixtures,…
    3. 301.3 Alternate Materials and Methods of Construc-
    4. 301.4 Flood Hazard Areas. Plumbing systems shall be
    5. 301.5 Alternative Engineered Design. An alternative
    6. 301.6 One- and Two-Family Dwellings. [HCD 1] The
    7. 301.7 OSHPD 1R [OSHPD 1R]. For OSHPD 1R, refer to
    8. 302.1 General. Iron, steel, copper, and copper alloy pipe
    9. 303.1 General. It shall be unlawful for a person to cause,
    10. 304.1 General. Plumbing fixtures, drains, appurtenances,
    11. 305.1 Unlawful Practices. It shall be unlawful for a person to…
    12. 306.1 Detrimental Wastes. Wastes detrimental to the public sew…
    13. 306.2 Safe Discharge. Sewage or other waste from a
    14. 307.1 System. Except as otherwise provided in this code,
    15. 307.2 Ownership. No subdivision, sale, or transfer of ownershi…
    16. 308.1 General. Piping, fixtures, or equipment shall not be
    17. 309.1 Engineering Practices. Design, construction, and
    18. 309.2 Concealing Imperfections. It is unlawful to conceal crac…
    19. 309.3 Burred Ends. Burred ends of pipe and tubing shall
    20. 309.4 Installation Practices. Plumbing systems shall be
    21. 309.5 Sound Transmission. Plumbing piping systems
    22. 309.6 Dead Legs. Dead legs shall have a method of flushing.
    23. 310.1 Fittings. No double hub fitting, single or double tee
    24. 310.2 Drainage and Vent Piping. No drainage or vent
    25. 310.3 Waste Connection. No waste connection shall be
    26. 310.4 Use of Vent and Waste Pipes. Except as hereinafter provi…
    27. 310.5 Obstruction of Flow. No fitting, fixture and piping
    28. 310.6 Dissimilar Metals. Except for necessary valves,
    29. 310.7 Direction of Flow. Valves, pipes, and fittings shall
    30. 310.8 Screwed Fittings. Screwed fittings shall be ABS,
    31. 310.9 [OSHPD 1, 2, 3, 4 & 5] Drainage piping over oper-
    32. 310.10 [OSHPD 1, 3, 4 & 5] Floor drains, waste traps, san-
    33. 310.11 [SFM] For applications listed in Section 1.11.0 regu-
    34. 310.12 [OSHPD 1, 2, 4 & 5] Services/Systems and Util-
    35. 310.13 Telephone and Data Equipment Rooms
    36. 311.1 General. The drainage system of each new building
    37. 312.1 General. Piping passing under or through walls shall
    38. 312.2 Installation. Piping in connection with a plumbing
    39. 312.3 Building Sewer and Drainage Piping. No building sewer or…
    40. 312.4 Corrosion, Erosion, and Mechanical Damage.
    41. 312.5 Protectively Coated Pipe. Protectively coated pipe
    42. 312.6 Freezing Protection. No water, soil, or waste pipe
    43. 312.7 Fire-Resistant Construction. Piping penetrations
    44. 312.8 Waterproofing of Openings. Joints at the roof
    45. 312.9 Steel Nail Plates. Plastic and copper or copper alloy
    46. 312.10 Sleeves. Sleeves shall be provided to protect piping th…
    47. 312.11 Structural Members. A structural member weakened or imp…
    48. 312.12 Rodentproofing. Strainer plates on drain inlets
    49. 313.1 General. Piping, fixtures, appliances, and appurtenances…
    50. 313.2 Material. Hangers and anchors shall be of sufficient
    51. 313.3 Suspended Piping. Suspended piping shall be supported at…
    52. 313.4 Alignment. Piping shall be supported in such a manner as…
    53. 313.5 Underground Installation. Piping in the ground
    54. 313.6 Hanger Rod Sizes. Hanger rod sizes shall be not
    55. 313.7 Gas Piping. Gas piping shall be supported by metal
    56. 313.8 [OSHPD 1, 2, 3, 4 & 5] Refer to Title 24, Part 2 of the
    57. 314.1 Trenches. Trenches deeper than the footing of a
    58. 314.2 Tunneling and Driving. Tunneling and driving shall
    59. 314.3 Open Trenches. Excavations required to be made
    60. 314.4 Excavations. Excavations shall be completely backfilled …
    61. 315.1 Unions. Approved unions shall be permitted to be
    62. 315.2 Prohibited Joints and Connections. A fitting or
    63. 316.1 General. Where different sizes of pipes and fittings
    64. 317.1 General. Food or drink shall not be stored, prepared,
    65. 318.1 General. Tests in accordance with this code, which
    66. 318.2 Pressure Tests (10 psi or less). Required pressure tests…
    67. 318.3 Pressure Tests (greater than 10 psi to 100 psi).
    68. 318.4 Pressure Tests (exceeding 100 psi). Required
    69. 318.5 Pressure Range. Test gauges shall have a pressure
    70. 319.1 General. Such piping shall be in accordance with the
    71. 320.1 General. Where pressure piping systems are rehabilitated…
  4. Chapter 4 — PLUMBING FIXTURES AND FIXTURE FITTINGS
  5. Chapter 5 — WATER HEATERS
  6. Chapter 6 — WATER SUPPLY AND DISTRIBUTION
  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 …

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