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Earlier editions: 20222019

Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS

1603.7 Above Grade. Above grade, storage tanks shall be

California Plumbing Code (Title 24, Part 5) · 2025 edition · updated 2026-09-10 · California

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

of an opaque material, approved for aboveground use in direct sunlight or shall be shielded from direct sunlight. Tanks shall be installed in an accessible location to allow for inspection and cleaning. The tank shall be installed on a foundation or platform that is constructed to accommodate loads in accordance with the California Building Code .

Exception: Tanks may be installed directly on grade in accor- dance with Section 1601.3.

FIGURE 1603.2 1603.8 Below Grade. Rainwater storage tanks installed below grade shall be structurally designed to withstand antic

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NONPOTABLE RAINWATER CATCHMENT SYSTEMS

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TABLE 1603.4

MINIMUM WATER QUALITY

APPLICATION MINIMUM TREATMENT MINIMUM WATER
QUALITY
Car washing Debris excluder or other
approved means in
accordance with Section
1603.17, and 100
microns_(100 µm)_in
accordance with Section
1603.18 for drip
irrigation.
N/A
_Surface,_Subsurface
and drip irrigation
Debris excluder or
other approved means
in accordance with
Section 1603.17, and
100 microns_(100 µm)_
in accordance with
Section 1603.18 for
drip irrigation.
N/A
Spray irrigation where
the maximum storage
volume is less than
360 gallons_(1363 L)_
Debris excluder or other
approved means in
accordance with Section
1603.17, and disinfec-
tion in accordance with
Section 1603.15.
N/A
Spray irrigation where
the maximum storage
volume is equal to or
more than 360 gallons
(1363 L)
Debris excluder or
other approved means
in accordance with Sec-
tion 1603.17.
Escherichia
coli: < 100
CFU/100 mL,
and Turbidity:
< 10 NTU
Urinal and water
closet flushing,
clothes washing, and
trap priming
Debris excluder or other
approved means in
accordance with Section
1603.17, and 100
microns_(100 µm)_ in
accordance with Section
1603.18.
Escherichia
coli: < 100
CFU/100 mL,
and Turbidity:
< 10 NTU
Ornamental fountains
and other water
features
Debris excluder or
other approved means
in accordance with
Section 1603.17.
Escherichia
coli: < 100
CFU/100 mL,
and Turbidity:
< 10 NTU
Cooling tower
make-up water
Debris excluder or other
approved means in
accordance with Section
1603.17, and 100
microns_(100 µm)_ in
accordance with Section
1603.18.
Escherichia
coli: < 100
CFU/100 mL,
and Turbidity:
< 10 NTU

For SI units: 1 micron = 1 µm, 1 gallon = 3.785 L

ipated 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 cov- ers 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. 1601.8 Material Compatibility. Rainwater catchment systems sha…
    9. 1601.9 System Controls. Controls for pumps, valves, and
    10. 1601.10 Separation Requirements. Underground rainwater catchme…
    11. 1601.11 Abandonment. Rainwater catchment systems that
    12. 1601.12 Sizing. Unless otherwise provided for in this chapter,…
    13. 1602.1 General. The installation, construction, alteration,
    14. 1602.2 Plumbing Plan Submission. No permit for a
    15. 1602.3 System Changes. No changes or connections shall
    16. 1602.4 Connections to Potable or Reclaimed (Recy-
    17. 1602.5 Initial Cross-Connection Test. Where a portion
    18. 1602.6 Sizing. The design and size of rainwater drains, gutter…
    19. 1602.7 Rainwater Catchment System Materials. Rain- 1603.3 Rain…
    20. 1602.8 Rainwater Catchment System Color and
    21. 1603.4 Minimum Water Quality. The minimum water
    22. 1602.9 Deactivation and Drainage for Cross-Connec- shall be in…
    23. 1603.1 Rainwater Catchment Systems. The design and
    24. 1603.2 Outside Hose Bibbs. Outside hose bibbs shall be infecti…
    25. 1603.5 Rainwater Storage Tanks. Rainwater storage tanks
    26. 1603.6 Location. Rainwater storage tanks shall be permitted to…
    27. 1603.7 Above Grade. Above grade, storage tanks shall be
    28. 1603.9 Drainage and Overflow. Rainwater storage tanks
    29. 1603.10 Opening and Access Protection. Rainwater
    30. 1603.11 Marking. Rainwater tanks shall be permanently
    31. 1603.12 Storage Tank Venting. Where venting using
    32. 1603.13 Pumps. Pumps serving rainwater catchment systems shall…
    33. 1605.1 General. Rainwater catchment systems shall be
    34. 1605.2 Supply System Inspection and Test. Rainwater
    35. 1605.3 Cross-Connection Inspection and Testing. An
    36. 1603.14 Roof Drains. Primary and secondary roof drains,
    37. 1603.15 Water Quality Devices and Equipment.
    38. 1603.16 Freeze Protection. Tanks and piping installed in
    39. 1603.17 Debris Removal. The rainwater catchment conveyance sys…
    40. 1603.18 Required Filters. A filter permitting the passage
    41. 1603.19 Roof Gutters. Gutters shall maintain a minimum
    42. 1603.20 Rainwater Diversion Valves. Rainwater diversion valves…
    43. 1604.1 General. Signs in buildings using rainwater shall be
    44. 1604.2 Commercial, Industrial, Institutional and Res-
    45. 1604.3 Equipment Room Signs. Each equipment room
  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

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