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Chapter 11 — STORM DRAINAGE

1101.15 Traps on Storm Drains and Leaders. Leaders

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.

and storm drains, where connected to a combined sewer, shall be trapped. Floor and area drains connected to a storm drain shall be trapped. Exception: Traps shall not be required where roof drains, rain leaders, and other inlets are at locations permitted under Section 906.0, Vent Termination.

1101.15.1 Where Not Required. No trap shall be required for leaders or conductors that are connected to a sewer carrying storm water exclusively. 1101.15.2 Trap Size. Traps, where installed for individual conductors, shall be the same size as the horizontal drain to which they are connected. 1101.15.3 Method of Installation of Combined Sewer. Individual storm-water traps shall be installed on the stormwater drain branch serving each storm-water inlet, or a single trap shall be installed in the main storm drain just before its connection with the combined building sewer. Such traps shall be provided with an accessible cleanout on the outlet side of the trap.

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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
  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
    Overview
    1. 1101.2 Where Required. Roofs, paved areas, yards, courts,
    2. 1101.3 Storm Water Drainage to Sanitary Sewer Pro-hibited. Sto…
    3. 1101.4 Material Uses. Pipe, tube, and fittings conveying
    4. 1101.5 Expansion Joints Required. Expansion joints or
    5. 1101.6 Subsoil Drains. Subsoil drains shall be provided
    6. 1101.9 Window Areaway Drains. Window areaways at a
    7. 1101.10 Filling Stations and Motor Vehicle WashingEstablishmen…
    8. 1101.11 Paved Areas. Where the occupant creates surface
    9. 1101.12 Roof Drainage. Roof drainage shall comply with
    10. 1101.7 Building Subdrains. Building subdrains located
    11. 1101.8 Areaway Drains. Open subsurface space adjacent
    12. 1101.13 Cleanouts. Cleanouts for building storm drains
    13. 1101.16 Leaders, Conductors, and Connections.
    14. 1101.14 Rainwater Sumps. Rainwater sumps serving
    15. 1101.15 Traps on Storm Drains and Leaders. Leaders
    16. 1102.2 Dome Strainers Required. Roof drains shall have
    17. 1102.3 Roof Drain Flashings. The connection between
    18. 1103.2 Size of Horizontal Storm Drains and Sewers.
    19. 1103.3 Size of Roof Gutters. The size of semi-circular
    20. 1103.4 Side Walls Draining onto a Roof. Where vertical walls p…
    21. 1104.0 Values for Continuous Flow.1104.1 General. Where there …
    22. 1105.0 Controlled-Flow Roof Drainage.1105.1 Application. Inste…
    23. 1105.2 Setback Roofs. Drains on setback roofs shall be
    24. 1106.2 Siphonic Roof Drainage Systems. The design of
    25. 1106.3 Siphonic Roof Drains. Siphonic roof drains shall
    26. 1107.2 Methods of Testing Storm Drainage Systems. Except for o…
  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 STANDARD FOR PEX TUBING SYSTEMS FOR …
  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

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