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Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS

1603.9 Below Grade. Rainwater storage tanks installed

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.

below grade shall be structurally designed to withstand anticipated earth or other loads. Holding tank covers shall be capable of supporting an earth load of not less than 300 pounds per square foot (lb/ft 2 ) (1465 kg/m 2 ) where the tank is designed for underground installation. Below grade rainwater tanks installed underground shall be provided with manholes. Below grade storage tanks, located outside of the building, shall be provided with either a manhole not less than 24 inches (610 mm) square or a manhole with an inside diameter of not less than 24 inches (610 mm). Service ports in manhole covers shall be not less than 8 inches (203 mm) in diameter. The manhole opening shall be not less than 20 inches (508 mm) in diameter and located not less than 4 inches (102 mm) above the surrounding grade. The surrounding grade shall be sloped away from the manhole. Underground tanks shall be ballasted, anchored, or otherwise secured, to prevent the tank from floating out of the ground where empty. The combined weight of the tank and hold down system shall meet or exceed the buoyancy force of the tank.

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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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