Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
1503.9 Gray Water System Components. Gray water
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.
system components shall comply with Section 1503.9.1 through Section 1503.9.4 .
[HCD 1] Gray water system components shall comply with this chapter.
(8) Where a surge tank is installed underground, the sys tem shall be designed so that the tank overflow will gravity drain to the existing sewer line or septic tank. The tank shall be protected against sewer line backflow by a backwater valve installed in accordance with this code. (9) Surge tanks shall be installed on dry, level, well compacted soil where underground or on a level 3
(9) Surge tanks shall be installed on dry, level, well compacted soil where underground or on a level 3 inch (76 mm) thick concrete slab or other approved method where aboveground. (10)Surge tanks shall be anchored to prevent against
overturning where installed aboveground. Under
1503.9.1 Surge Tanks. Where installed, surge tanks shall be in accordance with the following: (1) Surge tanks shall be constructed of solid, durable
materials not subject to excessive corrosion or decay
(10)Surge tanks shall be anchored to prevent against
overturning where installed aboveground. 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 forces of the tank. (11) [HCD 1] An overflow drain and backwater valve is
not required on a clothes washer system.
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(1) Surge tanks shall be constructed of solid, durable
materials not subject to excessive corrosion or decay and shall be watertight. Aboveground surge tanks shall be protected from direct sunlight or shall be con- structed of UV resistant materials including but not limited to heavily tinted or opaque plastic, fiberglass, lined metal, concrete and wood. Surge tanks constructed of steel shall be approved by the Authority Having Jurisdiction, provided such tanks are in accordance with approved applicable standards. (2) Each surge tank shall be vented in accordance with
this code. The vent size shall be determined based
(2) Each surge tank shall be vented in accordance with
this code. The vent size shall be determined based on the total gray water fixture units as outlined in this code. (3) Each surge tank shall have an access opening with
lockable gasketed covers or approved equivalent to
(3) Each surge tank shall have an access opening with
lockable gasketed covers or approved equivalent to allow for inspection and cleaning. (4) Each surge tank shall have its rated capacity perma nently marked on the unit. Also, a sign stating GRAY
(11) [HCD 1] An overflow drain and backwater valve is
not required on a clothes washer system. 1503.9.2 Gray Water Pipe and Fitting Materials. Aboveground and underground building drainage and vent pipe and fittings for gray water systems shall comply with the requirements for aboveground and underground sanitary building drainage and vent pipe and fittings in this code. These materials shall extend not less than 2 feet (610 mm) outside the building. 1503.9.3 Animals and Insects. Gray water tank openings shall be protected to prevent the entrance of insects, birds, or rodents into the tank and piping sys- tems. Screens installed on vent pipes, inlets, and over- flow pipes shall have an aperture of not greater than 1 ⁄16 of an inch (1.6 mm) and shall be close fitting. 1503.9.4 Freeze Protection. Tanks and piping installed in locations subject to freezing shall be provided with an approved means of freeze protection.
(4) Each surge tank shall have its rated capacity perma nently marked on the unit. Also, a sign stating GRAY WATER SYSTEM, CAUTION - UNSAFE WATER shall be permanently marked on the holding tank. (5) Each surge tank shall have an overflow drain. The
overflow drains shall have permanent connections
(5) Each surge tank shall have an overflow drain. The
overflow drains shall have permanent connections to the building drain or building sewer, upstream of septic tanks. The overflow drain shall not be equipped with a shutoff valve. (6) The overflow drain pipes shall not be less in size
than the inlet pipe. Unions or equally effective fit
The overflow drain pipes shall not be less in size
than the inlet pipe. Unions or equally effective fittings shall be provided for piping connected to the surge tank.
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Ask AI about this code▸Contents — California Plumbing Code (Title 24, Part 5)
- Chapter 1 — GENERAL CODE PROVISIONS
- Chapter 2 — DEFINITIONS
- Chapter 3 — GENERAL REGULATIONS
- Chapter 4 — PLUMBING FIXTURES AND FIXTURE FITTINGS
- Chapter 5 — WATER HEATERS
- Chapter 6 — WATER SUPPLY AND DISTRIBUTION
- Chapter 7 — SANITARY DRAINAGE
- Chapter 8 — INDIRECT WASTES
- Chapter 9 — VENTS
- Chapter 10 — TRAPS AND INTERCEPTORS
- Chapter 11 — STORM DRAINAGE
- Chapter 12 — FUEL GAS PIPING
- Chapter 13 — HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICA…
- Chapter 14 — FIRESTOP PROTECTION
▸Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
Overview- 1501.0 General.1501.1 Applicability [BSC-CG, DWR & HCD 1]. The
- 1501.2 System Design. Alternate water source systems
- 1501.3 Permit [BSC-CG, HCD 1, DWR]. It shall be unlawful for a…
- 1501.4 Component Identification. System components
- 1501.5 Maintenance and Inspection 1, DWR]. Alternate water sou…
- 1501.6 Operation and Maintenance Manual [BSC-
- 1501.7 Minimum Water Quality Requirements [BSC-
- 1501.8 Material Compatibility. Alternate water source systems …
- 1501.9 Signage [BSC-CG, HCD 1, HCD 2, HCD 1-AC, &DWR]. Signage…
- 1501.10 System Controls. Controls for pumps, valves, and
- 1501.11 Hose Bibbs for Single-Family Dwellings [HCD1]. Hose bi…
- 1502.2 Supply System Inspection and Test. Alternate
- 1502.3 Cross-Connection Inspection and Testing. An
- 1502.6 Sizing. Unless otherwise provided for in this chapter, …
- 1503.1 General. The provisions of this section shall apply
- 1502.4 Separation Requirements. Underground alternate
- 1502.5 Abandonment. Alternate water source systems that
- 1503.2 System Requirements. Gray water shall be permitted to b…
- 1503.3 Connections to Potable and Reclaimed(Recycled) Water Sy…
- 1503.4 Location. No gray water system or part thereof shall
- 1503.5 Plot Plan Submission. No permit for a gray water
- 1503.6 Prohibited Location. Where there is insufficient
- 1503.7 Drawings and Specifications. The Authority
- 1503.9 Gray Water System Components. Gray water
- 1504.2 Required Area of Subsurface Irrigation
- 1504.3 Determination of Maximum Absorption Capac-
- 1504.4 Groundwater Level. No excavation for an irrigation fiel…
- 1504.5 Irrigation, Disposal Field and Mulch Basin Con-structio…
- 1504.6 Reserved.
- 1504.7 Reserved.
- 1504.8 Gray Water System Color and Marking Infor-mation. Press…
- 1504.9 Other Collection and Distribution Systems. Other collec…
- 1504.10 Testing. Building drains and vents for gray water
- 1504.11 Maintenance. Gray water systems and components shall b…
- 1505.0 Recycled Water 1505.1 General. The provisions of Supply…
- 1505.3 System Changes. No changes or connections shall
- 1505.4 Connections to Potable or Reclaimed (Recy-cled) Water S…
- 1505.2 Permit. It shall be unlawful for a person to construct,
- 1505.5 Initial Cross-Connection Test. A cross-connection test …
- 1505.6 Recycled Water Recycled water supply system materials s…
- 1505.8 Valves. Valves, except fixture supply control valves,
- 1505.9 Hose Bibbs. Hose bibbs shall not be allowed on
- 1505.10 Required Appurtenances. The recycled water
- 1505.11 Pipe Separation in Trenches. Reclaimed (recycled) wate…
- 1505.12 Signage. Signs in rooms and water closet tanks in
- 1505.13 Inspection and Testing. Recycled water supply
- 1505.15 Maintenance and Inspection. Recycled water
- 1506.0 On-Site Treated Nonpotable Gray Water Sys-
- 1506.2 Plumbing Plan Submission. No permit for an
- 1506.3 System Changes. No changes or connections shall
- 1506.4 Connections to Potable or Reclaimed (Recy-
- 1506.5 Initial Cross-Connection Test. A cross-connection test …
- 1506.6 On-Site Treated Nonpotable tem Materials. On-site treat…
- 1506.7 On-Site Treated Nonpotable Devices and Systems. Devices…
- 1506.9 Design and Installation. The design and installation of…
- 1506.10 Valves. Valves, except fixture supply control
- 1506.11 Signs. Signs in buildings using on-site treated nonpot…
- 1506.12 Inspection and Testing. On-site treated nonpotable gra…
- Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS
- Chapter 17 — REFERENCED STANDARDS
- Appendix A — RECOMMENDED RULES FOR SIZING THE WATER SUPPLY SYS…
- Appendix B — EXPLANATORY NOTES ON COMBINATION WASTE AND VENT S…
- Appendix C — ALTERNATE PLUMBING SYSTEMS
- Appendix D — SIZING STORM WATER DRAINAGE SYSTEMS
- Appendix E — MANUFACTURED/MOBILE HOME PARKS AND RECREATIONAL V…
- Appendix F — FIREFIGHTER BREATHING AIR REPLENISHMENT SYSTEMS
- Appendix G — SIZING OF VENTING SYSTEMS
- Appendix H — PRIVATE SEWAGE DISPOSAL SYSTEMS
- Appendix I — INSTALLATION STANDARD FOR PEX TUBING SYSTEMS FOR …
- Appendix J — COMBINATION OF INDOOR AND OUTDOOR COMBUSTION AND …
- Appendix K — POTABLE RAINWATER CATCHMENT SYSTEMS
- Appendix L — SUSTAINABLE PRACTICES
- Appendix M — PEAK WATER DEMAND CALCULATOR