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Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS

1603.10 Drainage and Overflow. Rainwater storage tanks

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.

shall be provided with a means of draining and cleaning. The overflow drain shall not be equipped with a shutoff valve. The overflow outlet shall discharge in accordance with this code for storm drainage systems. Where discharging to the storm drainage system, the overflow drain and tank drain shall be protected from backflow of the storm drainage system by a backwater valve or other approved method. Back- water valves shall be installed so that access is provided to the working parts for service and repair.

1603.10.1 Overflow Outlet Size. The overflow outlet shall be sized to accommodate the flow of the rainwater entering the tank and not less than the aggregate cross-sectional area of inflow pipes.

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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
  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
    Overview
    1. 1601.1 Applicability. The provisions of this chapter shall
    2. 1601.2 System Design. Rainwater catchment systems shall
    3. 1601.3 Permit. It shall be unlawful for a person to construct,
    4. 1601.4 Component Identification. System components
    5. 1601.5 Maintenance and Inspection. Rainwater catchment systems…
    6. 1601.6 Operation and Maintenance Manual. An operation and main…
    7. 1601.7 Minimum Water Quality Requirements. The
    8. 1602.1 General. The installation, construction, alteration,
    9. 1602.2 Plumbing Plan Submission. No permit for a
    10. 1602.3 System Changes. No changes or connections shall
    11. 1602.4 Connections to Potable or Reclaimed (Recy-
    12. 1602.5 Initial Cross-Connection Test. Where a portion
    13. 1602.6 Sizing. The design and size of rainwater drains, gutter…
    14. 1602.7 Rainwater Catchment System Materials. Rainwater catchme…
    15. 1602.8 Rainwater Catchment System Color and
    16. 1602.9 Deactivation and Drainage for Cross-Connec-
    17. 1603.1 Rainwater Catchment Systems. The design and
    18. 1603.2 Outside Hose Bibbs. Outside hose bibbs shall be
    19. 1603.3 Construction. Rainwater storage tanks shall be
    20. 1603.4 Rainwater Catchment Collection Surfaces.
    21. 1603.5 Minimum Water Quality. The minimum water
    22. 1603.12 Marking. Rainwater tanks shall be permanently
    23. 1603.13 Storage Tank Venting. Where venting using
    24. 1603.14 Pumps. Pumps serving rainwater catchment systems shall…
    25. 1603.15 Roof Drains. Primary and secondary roof drains,
    26. 1603.16 Water Quality Devices and Equipment.
    27. 1603.17 Freeze Protection. Tanks and piping installed in
    28. 1603.18 Debris Removal. The rainwater catchment conveyance sys…
    29. 1603.19 Required Filters. A filter permitting the passage
    30. 1603.6 Rainwater Storage Tanks. Rainwater storage
    31. 1603.7 Location. Rainwater storage tanks shall be permitted to…
    32. 1603.8 Above Grade. Above grade, storage tanks shall be
    33. 1603.9 Below Grade. Rainwater storage tanks installed
    34. 1603.10 Drainage and Overflow. Rainwater storage tanks
    35. 1603.11 Opening and Access Protection. Rainwater
    36. 1603.20 Roof Gutters. Gutters shall maintain a minimum
    37. 1604.1 General. Signs in buildings using rainwater shall be
    38. 1604.2 Commercial, Industrial, Institutional and Res-
    39. 1604.3 Equipment Room Signs. Each equipment room
    40. 1605.1 General. Rainwater catchment systems shall be
    41. 1605.2 Supply System Inspection and Test. Rainwater
    42. 1605.3 Cross-Connection Inspection and Testing. An
  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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