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Earlier editions: 20222019

Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS

1604.3 Equipment Room Signs. Each equipment room

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.

containing nonpotable rainwater equipment shall have a sign posted with the following wording in 1 inch (25.4 mm) let ters:

NONPOTABLE RAINWATER CATCHMENT SYSTEMS

(3) Fixtures, potable, and rainwater shall be tested and inspected for flow. Flow from a rainwater catchment water system outlet shall indicate a cross-connection. No flow from a potable water outlet shall indicate that it is connected to the rainwater system.

(4) The drain on the rainwater catchment water system shall be checked for flow during the test and at the end of the period.

(5) The potable water system shall then be completely drained.

(6) The rainwater catchment water system shall then be activated and pressurized. When rainwater is not available for the initial cross-connection test, a tem- porary connection to a potable water supply shall be required. At the conclusion of the initial cross- connection test, the temporary connection to the potable water supply shall be disconnected.

(7) The rainwater catchment water system shall remain pressurized for a minimum period of time specified by the Authority Having Jurisdiction while the potable water system is empty. The minimum period the potable water system is to remain depressurized shall be determined on a case-by-case basis, but in no case shall that period be less than 1 hour.

(8) Fixtures, potable and rainwater catchment, shall be tested and inspected for flow. Flow from a potable water system outlet shall indicate a cross-connection. No flow from a rainwater catchment water outlet shall indicate that it is connected to the potable water system.

(9) The drain on the potable water system shall be checked for flow during the test and at the end of the period.

(10)Where there is no flow detected in the fixtures which would indicate a cross-connection, the potable water system shall be repressurized. 1605.3.3 Discovery of Cross-Connection. In the event that a cross-connection is discovered, the following procedure, in the presence of the Authority Having Jurisdiction, shall be activated immediately:

(1) Rainwater catchment piping to the building shall be shutdown at the supply source(s), and the rainwater riser shall be drained.

(2) Potable water piping to the building shall be shutdown at the meter.

(3) The cross-connection shall be uncovered and disconnected.

(4) The building shall be retested following procedures listed in Section 1605.3.1 and Section 1605.3.2.

(5) The potable water system shall be chlorinated with 50 ppm chlorine for 24 hours.

(6) The potable water system shall be flushed after 24 hours, and a standard bacteriological test shall be performed. Where test results are acceptable, the potable water system shall be permitted to be recharged.

332 2025 CALIFORNIA PLUMBING CODE

CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE

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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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