CRC · California Residential Code
Minimum potable water supply to fixtures
In plain terms: every plumbing fixture must get potable running water piped to it so it can flush and stay sanitary (see **§ 601.2**). If home sprinklers share the same domestic piping, calculate sprinkler design flow using **§ R309.3.4.2** (largest room flow; two or more sprinklers = highest flow × 2), size piping and supply to deliver that flow at the required pressure, and provide the required duration (7 or 10 minutes). When the water service is common to both systems, add **5 gpm** for pipe sizing at the connection point.
Last reviewed: July 6, 2026
What the code requires
Each plumbing fixture must have an adequate supply of potable water delivered by piping so the fixture can be flushed and kept clean and sanitary without risk of backflow or cross‑connection — this is the baseline rule in § 601.2 of the California codes.
When an automatic (multipurpose) sprinkler system supplies both sprinklers and fixtures, the sprinkler system’s design flow is set by the sprinkler rules in § R309.3.4.2, and the water supply must provide that design flow for the required duration.
Every fixture must be provided with potable running water piped to it so it can flush and remain sanitary; if sprinklers are part of the same piping, size and duration rules in R309 apply.
Requirements in detail
Core plumbing requirement (potable supply to fixtures)
- The water distribution chapter applies to water supply materials, design, installation and backflow prevention (§ 601.1).
- § 601.2 requires: each plumbing fixture shall be provided with an adequate supply of potable running water piped thereto in an approved manner, arranged to flush and keep the fixture sanitary and without danger of backflow or cross‑connection. Water closets and urinals must be flushed by an approved flush tank or flushometer valve.
Sprinkler (multipurpose) systems that share the potable supply
- Determining design flow (how much water the sprinkler portion requires):
The design flow for a room is set by § R309.3.4.2:- A room with one sprinkler → use that sprinkler’s required flow (per manufacturer/listing).
- A room with two or more sprinklers → identify the sprinkler with the highest required flow and multiply that flow by 2.
- The system design flow is the largest room flow calculated. § R309.3.4.2.
- Water supply pressure & duration: The water supply shall provide not less than the design flow at the pressure used for pipe sizing; when the supply serves both domestic and fire sprinklers, add 5 gpm (19 L/min) at the connection point for determining common pipe sizing unless provisions prevent flow into the domestic system. § R309.3.5.
- Duration required from the supply (storage or pump sizing):
- 7 minutes for one‑story dwellings under 2,000 ft².
- 10 minutes for dwellings two or more stories or ≥ 2,000 ft². § R309.3.5.2.
- Pipe sizing: Piping for sprinklers is sized for the flow required by § R309.3.4.2; the flow required to supply ordinary plumbing fixtures is generally not added to the sprinkler design flow for hydraulic sizing, but see the 5 gpm rule where systems are common. § R309.3.6.
Decision‑relevant quick reference table
| Decision factor / value | Practical meaning | Code Reference |
|---|---|---|
| Each fixture must have potable running water piped to it | Baseline duty for every plumbing fixture | § 601.2 |
| Chapter that controls water supply systems | Materials, design, installation, backflow prevention | § 601.1 |
| Sprinkler system design flow (one sprinkler) | Use manufacturer/listed flow for that sprinkler | § R309.3.4.2 (1) |
| Sprinkler system design flow (≥ two sprinklers) | Highest sprinkler flow × 2 | § R309.3.4.2 (2) |
| Add-on when sprinkler and domestic supplies share | + 5 gpm (19 L/min) added at connection when systems are common | § R309.3.5 |
| Required supply duration | 7 minutes (<2,000 ft², one story); 10 minutes (≥2,000 ft² or multi‑story) | § R309.3.5.2 |
| Minimum residual pressure for fixtures (plumbing) | If supply pressure insufficient, tank+pump to provide 15 psi at fixture inlets | § 608.1 |
| Minimum reserve for limited‑density rural owner‑built dwellings | 50 gallons (189 L) potable reserve allowed where water not piped | § 601.2 Exception (3) |
Notes about defined terms
- Potable water is defined as water meeting bacteriological and chemical quality requirements of the public health authority. Potable is the required water type for fixtures.
Exceptions & special cases
- Fixtures that are listed as not requiring water (and not connected) are excepted from § 601.2.
- The Authority Having Jurisdiction (AHJ) may waive potable running water to a fixture where not necessary for safety and sanitation.
- Limited‑density owner‑built rural dwellings: potable water must be available on site but need not be pressurized; where not piped there must be a minimum reserve of 50 gallons (189 L). § 601.2 Exception (3).
- Alternate water sources (rainwater, graywater, recycled water) may be allowed per Chapter 15 — these are subject to the nonpotable identification and cross‑connection protections in Chapter 6 and related sections. § 601.2 Exceptions (4) & 601.3.
- For multipurpose sprinklers containing antifreeze or chemical additives, backflow protection and reduced‑pressure assemblies are required (R309.3.5.3.1).
Common mistakes
- Thinking fixture flows must be hydraulically added to sprinkler flows. The code says fixture supply flows are not required to be added to sprinkler design flow for sizing, but when the water service supplies both systems and no device prevents domestic flow during sprinkler activation, you must add 5 gpm for sizing common piping. Don’t conflate these two rules. § R309.3.6 and § R309.3.5.
- Forgetting the duration requirement (7 or 10 minutes) when sizing tanks or pump run times for well/tank systems — this is essential for supply capacity. § R309.3.5.2.
- Installing devices that will restrict flow (water softeners, filters, shutoffs) on the service without reviewing the sprinkler design — the code prohibits valves that isolate sprinklers and requires an owner warning sign about flow‑restricting devices. § R309.3.3.2 and § R309.3.7.
- Using nonpotable water (rainwater/recycled) for fixtures without complying with Chapter 15 and proper labeling/identification and backflow protection in Chapter 6. § 601.3 and Chapter 15 references.
Worked example
Scenario: 1‑story single family dwelling, 1,500 ft², using a multipurpose sprinkler/fixture system.
Determine room design flow per § R309.3.4.2: the largest room has two sprinklers; the manufacturer’s listing shows the highest sprinkler in that room requires 20 gpm at its rated pressure. For two or more sprinklers you use highest flow × 2 = 20 gpm × 2 = 40 gpm. § R309.3.4.2 (2).
Duration: one‑story and less than 2,000 ft² → supply must provide that design flow for 7 minutes. So the supply must sustain 40 gpm for 7 minutes (i.e., required stored volume = 40 gpm × 7 min = 280 gallons if relying on stored water). § R309.3.5.2.
If the water service also supplies domestic fixtures with no device preventing flow into the domestic system, add 5 gpm at the connection point for sizing common piping (for pipe sizing only — total sprinkler demand remains 40 gpm). So use 45 gpm when selecting water‑service pipe and determining pressure losses for shared piping. § R309.3.5.
Confirm pressure: use the pressure required by the sprinkler manufacturer for the chosen flow and perform the R309.3.6 sizing steps (Psup − service/meter/device/elevation losses = Pt used in the sizing tables). § R309.3.6.
This example uses the code’s method (highest listed sprinkler flow × 2, duration rule, and the +5 gpm shared‑supply rule); the actual sprinkler flow must be taken from the sprinkler manufacturer’s published listing. § R309.3.4.1, § R309.3.4.2, § R309.3.5.
Related provisions (quick list)
- § 601.1 — Chapter applicability: water supply systems and backflow prevention.
- § 601.2 — Each plumbing fixture must be provided with potable running water arranged to flush and remain sanitary.
- § R309.3.4.2 — System design flow calculation rules for dwelling sprinklers.
- § R309.3.5 / R309.3.5.2 — Water supply requirements and required duration (7 / 10 minutes).
- § R309.3.6 — Pipe sizing and the procedure/tables for sprinkler piping.
- § 601.3 — Identification of potable vs nonpotable systems (labels, color codes).
- § 608.1 — Minimum residual water pressure to fixtures (when to provide tank + pump; 15 psi baseline).
Code references
Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:
CRC § 12.3 High relevance — show source text
12.3_|||||||||||||||||||||X|||| |Table 610.3||||X|X|||||||||||||||||||| |610.5||||X|X|||||||||||||||||||| |612.0|||X|||||||||||||||||||||| |612.1|||X|||||||||||||||||||||| |613.0||||||||||X||X|X|X|X|||||||||| |Table 613.1||||||||||X||X|X|X|X|||||||||| |614.0||||||||||X||X|X|X|X|||||||||| |615.0||||||||||X|X|X|X|X|X|||||||||| |616.0||||||||||X|||||||||||||||
This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.
136 2025 CALIFORNIA PLUMBING CODE
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CHAPTER 6
WATER SUPPLY AND DISTRIBUTION
601.0 General.
601.1 Applicability. This chapter shall govern the materials, design, and installation of water supply systems, including methods and devices used for backflow prevention. 601.2 Water Supply and Flushing. Each plumbing fixture shall be provided with an adequate supply of potable running water piped thereto in an approved manner, so arranged as to flush and keep it in a clean and sanitary condition without danger of backflow or cross-connection. Water closets and urinals shall be flushed using an approved flush tank or flushometer valve.
Exceptions:
(1) Listed fixtures that do not require water for their operation and are not connected to the water supply.
(2) Where not deemed necessary for safety and sanitation by the Authority Having Jurisdiction. (3) [HCD 1 & HCD 2] For limited-density owner-built rural dwellings, potable water shall be available to the dwelling site, although such water need not be pressur- ized. Where water is not piped from a well, spring, cistern or other source, there shall be a minimum reserve of 50 gallons (189 L) of potable water available. Where water delivery is pressurized, piping shall be installed in accor- dance with the provisions of this chapter. (4) [HCD 1, HCD 2 & DWR] For all residential occupan- cies, alternate water sources may be allowed as speci- fied in Chapter 15 of this code in addition to potable
water.
(5) [BSC-CG & DWR] For non-residential occupancies, alternate water sources may be allowed as specified in Chapter 15 of this code.
CRC § 1.11.0. High relevance — show source text
This state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.0.
2025 CALIFORNIA PLUMBING CODE 543
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544 2025 CALIFORNIA PLUMBING CODE
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APPENDIX R
TINY HOUSES
The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.
R 101.0 Tiny Houses.
R 101.1 Applicability. This appendix shall apply to structures permanently attached to a foundation. The tiny house plumbing systems shall be designed and installed in accordance with the requirements of this appendix and the requirements of this code. The provision of this appendix shall apply to permanent structures of 400 square feet (37 m [2] )or less. The provisions of this appendix shall not apply to recreational vehicles as defined in NFPA 1192 or to manufactured homes
as defined in NFPA 501A.
R 102.0 Definitions.
R 102.1 General. For purposes of this appendix, the following definition shall apply:
Tiny House. A single family dwelling that, is not greater than 400 square feet (37 m [2] ), not including loft area.
R 103.0. General.
R 103.1 Permits and Construction Documents. Per mits and construction documents shall be submitted and approved in accordance with Section 104.0. R 103.2 Fuel-Gas Piping System. Gas piping system shall be sized and installed in accordance with Chapter 12.
R 103.3 Water Heaters. Water heaters shall be installed in accordance with Chapter 5 and the manufacturer’s recommendations and instructions.
R 103.4 Potable Water Sources. Where a public water supply system is available, it shall be used. Private or alternate water sources shall comply with the potable water standards of the state, and local health authority. R 103.5 Water Supply to Fixtures. Each plumbing fixture shall be provided with an adequate supply of potable water in accordance with Chapter 6.
R 103.6 Protection of Potable Water. The potable water supply shall be protected from pollution and contamination in accordance with Section 602.0 and Section 603.0. Backflow prevention shall be in accordance with Table 603.2.
R 103.7 Water-Treatment Equipment. Where installed, water-treatment equipment shall comply with the requirements of Section 611.0.
R 103.8 Testing. Installations of water supply, drainage, and venting systems shall be tested and inspected in accordance with the requirements of this code.
R 201.0 Tiny House Fixtures.
R 201.1 Fixtures. Plumbing fixtures shall comply with the requirements of Chapter 4.
R 201.2 Kitchen. Each tiny house shall be provided with a kitchen sink.
R 201.3 Bathroom. Each tiny house shall be provided with not less than one water closet, one lavatory, and one bath, shower or combination bath/shower.
CRC § 1.0 Medium relevance — show source text
0|–| |Dental Unit, cuspidor|1⁄2|–|1.0|–| |Dishwasher, domestic|1⁄2|1.5|1.5|–| |Drinking Fountain or Water Cooler|1⁄2|0.5|0.5|0.75| |Hose Bibb|1⁄2|2.5|2.5|–| |Hose Bibb, each additional7|1⁄2|1.0|1.0|–| |Lavatory|1⁄2|1.0|1.0|1.0| |Lawn Sprinkler, each head5|–|1.0|1.0|–| |Mobile Home, each (minimum)|–|12.0|–|–| |Sinks|–|–|–|–| |Bar|1⁄2|1.0|2.0|–| |Clinical Faucet|1⁄2|–|3.0|–| |Clinical Flushometer Valve with or without faucet|1|–|8.0|–| |Kitchen, domestic with or without dishwasher|1⁄2|1.5|1.5|–| |Laundry|1⁄2|1.5|1.5|–| |Service or Mop Basin|1⁄2|1.5|3.0|–| |Washup, each set of faucets|1⁄2|–|2.0|–| |Shower per head|1⁄2|2.0|2.0|–| |Urinal, 1.0 GPF Flushometer Valve|3⁄4|3.0|4.0|5.0| |Urinal, greater than 1.0 GPF Flushometer Valve|3⁄4|4.0|5.0|6.0| |Urinal, flush tank|1⁄2|2.0|2.0|3.0| |Wash Fountain, circular spray|3⁄4|–|4.0|–| |Water Closet, 1.6 GPF Gravity Tank|1⁄2|2.5|2.5|3.5| |Water Closet, 1.6 GPF Flushometer Tank|1⁄2|2.5|2.5|3.5| |Water Closet, 1.6 GPF Flushometer Valve|1|5.0|5.0|8.0| |Water Closet, greater than 1.6 GPF Gravity Tank|1⁄2|3.0|5.5|7.0| |Water Closet, greater than 1.6 GPF Flushometer Valve|1|7.0|8.0|10.0|
For SI units: 1 inch = 25 mm
Notes: 1 Size of the cold branch pipe, or both the hot and cold branch pipes. 2 Appliances, appurtenances, or fixtures not included in this table shall be permitted to be sized by reference to fixtures having a similar flow rate and frequency of use. 3 The listed fixture unit values represent their total load on the cold water building supply. The separate cold water and hot water fixture unit value for fixtures having both cold and hot water connections shall be permitted to be three-quarters of the listed total value of the fixture. 4 The listed minimum supply branch pipe sizes for individual fixtures are the nominal (I.D.) pipe size.
CRC § 103.3 Medium relevance — show source text
R 103.3 Water Heaters. Water heaters shall be installed in accordance with Chapter 5 and the manufacturer’s recommendations and instructions.
R 103.4 Potable Water Sources. Where a public water supply system is available, it shall be used. Private or alternate water sources shall comply with the potable water standards of the state, and local health authority. R 103.5 Water Supply to Fixtures. Each plumbing fixture shall be provided with an adequate supply of potable water in accordance with Chapter 6.
R 103.6 Protection of Potable Water. The potable water supply shall be protected from pollution and contamination in accordance with Section 602.0 and Section 603.0. Backflow prevention shall be in accordance with Table 603.2.
R 103.7 Water-Treatment Equipment. Where installed, water-treatment equipment shall comply with the requirements of Section 611.0.
R 103.8 Testing. Installations of water supply, drainage, and venting systems shall be tested and inspected in accordance with the requirements of this code.
R 201.0 Tiny House Fixtures.
R 201.1 Fixtures. Plumbing fixtures shall comply with the requirements of Chapter 4.
R 201.2 Kitchen. Each tiny house shall be provided with a kitchen sink.
R 201.3 Bathroom. Each tiny house shall be provided with not less than one water closet, one lavatory, and one bath, shower or combination bath/shower.
R 201.4 Bathtubs and Whirlpool Bathtubs. Where installed, bathtubs and whirlpool bathtubs shall be in accordance with Section 409.0.
R 201.5 Showers Compartments. Where installed, shower compartment enclosures shall be not less than 30 inches (762 mm) wide by 30 inches (762 mm) long.
R 201.6 Water Closet. Water closets shall be in accordance
with Section 411.0.
R 201.7 Lavatories. Lavatories shall be in accordance with
Section 407.0.
R 202.0 Tiny House Water Supply System. R 202.1 Water Service Outlet. Each tiny house shall be provided with a water service outlet delivering potable water. The water service outlet riser shall be not less than ¾ of an inch (20 mm) nominal pipe size. R 202.2 Sizing Water Supply and Distribution Sys- tems. Water distribution systems shall be sized in accordance with Section 610.0. Water supply piping, joints, and connections shall be installed in accordance with Chapter 6. R 202.3 Pressure. Each tiny house water distribution system shall be so designed and maintained at not less than 15 pounds force per square inch (psi) (103 kPa) at each fixture inlet in accordance with Section 608.1. Water pressure exceeding 80 psi (552 kPa), shall be limited in accordance with Section 608.2.
R 203.0 Tiny House Drain, Waste, and Vent (DWV) System. R 203.1 General. Sanitary drain, waste, and vent (DWV) systems shall be installed in accordance with Chapter 7 and Chapter 9. The DWV system shall connect to the public sanitary waste system. Private sewage disposal systems shall be permitted where approved by the Authority Having Jurisdiction. See Appendix H for private sewage disposal system general guidelines.
CRC § 1603.19 Medium relevance — show source text
1603.19 Roof Gutters. Gutters shall maintain a minimum slope and be sized in accordance with Section 1103.3.
1603.20 Rainwater Diversion Valves. Rainwater diversion valves ranging from 2 inches (50 mm) through 12 inches (300 mm) in diameter shall be an approved diverter valve . Valves shall be readily accessible and include a filter located upstream of the valve when required.
1604.0 Signs. 1604.1 General. Signs in buildings using rainwater shall be in accordance with Section 1604.2 and Section 1604.3 , and applicable requirements of the California Building Code .
1604.2 Commercial, Industrial, Institutional and Res- idential Restroom Signs. A sign shall be installed in restrooms in commercial, industrial, and institutional occupancies , and in residential common use areas using nonpotable rainwater for water closets, urinals, or both. Signs shall comply with all applicable requirements of the Califor- nia Building Code. Each sign shall contain the following text:
TO CONSERVE WATER, THIS BUILDING USES RAINWATER TO FLUSH TOILETS AND URINALS.
1604.3 Equipment Room Signs. Each equipment room containing nonpotable rainwater equipment shall have a sign posted with the following wording in 1 inch (25.4 mm) let ters:
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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.
CRC § 601.1 Medium relevance — show source text
601.1 Applicability. This chapter shall govern the materials, design, and installation of water supply systems, including methods and devices used for backflow prevention. 601.2 Water Supply and Flushing. Each plumbing fixture shall be provided with an adequate supply of potable running water piped thereto in an approved manner, so arranged as to flush and keep it in a clean and sanitary condition without danger of backflow or cross-connection. Water closets and urinals shall be flushed using an approved flush tank or flushometer valve.
Exceptions:
(1) Listed fixtures that do not require water for their operation and are not connected to the water supply.
(2) Where not deemed necessary for safety and sanitation by the Authority Having Jurisdiction. (3) [HCD 1 & HCD 2] For limited-density owner-built rural dwellings, potable water shall be available to the dwelling site, although such water need not be pressur- ized. Where water is not piped from a well, spring, cistern or other source, there shall be a minimum reserve of 50 gallons (189 L) of potable water available. Where water delivery is pressurized, piping shall be installed in accor- dance with the provisions of this chapter. (4) [HCD 1, HCD 2 & DWR] For all residential occupan- cies, alternate water sources may be allowed as speci- fied in Chapter 15 of this code in addition to potable
water.
(5) [BSC-CG & DWR] For non-residential occupancies, alternate water sources may be allowed as specified in Chapter 15 of this code.
(6) [DWR] Where a public agency requires a building to use recycled water to flush water closets and urinals in accordance with California Water Code 13554. 601.2.1 Submeters. [HCD 1] Submeters (or meters) shall be installed to measure potable and reclaimed (recycled) water (hot and cold) that is supplied for the exclusive use of an individual dwelling unit within a newly constructed, multiunit rental residential structure; or for the use of an individual dwelling unit within a newly constructed mixed-use rental residential/commer- cial structure. Submeters (or meters) shall be installed in accordance with this code and the manufacturer’s installation instructions.
See Water Code Section 517 for definitions of “multiunit residential structure” and “mixed-use resi-
dential and commercial structure.” See also Civil Code commencing with Section 1954.201.
Exemptions:
(1) Long-term health care facilities as defined in Health and Safety Code Section 1418.
(2) Low-income housing as defined in Health and Safety Code Section 17922.14 (c)(2)(B).
(3) Residential care facilities for the elderly as defined in Health and Safety Code Section 1569.2 (p)(1).
(4) Housing at a place of education as defined in Title 24 of the California Code of Regulations, Califor- nia Building Code, Part 2, Section 202.
(5) Time-share property as defined in Business and Pro- fessions Code Section 11212, Subdivision (aa).
CRC § 25.4 Medium relevance — show source text
2 Vertical walls, ribs, or similar obstructions extending from the water surface to or above the horizontal plane of the spout opening other than specified in Footnote 1 above. The effect of three or more such vertical walls or ribs has not been determined. In such cases, the air gap shall be measured from the top of the wall. 3 The effective opening shall be the minimum cross-sectional area at the seat of the control valve or the supply pipe or tubing that feeds the device or outlet. Where two or more lines supply one outlet, the effective opening shall be the sum of the cross-sectional areas of the individual supply lines or the area of the single outlet, whichever is smaller. 4 Air gaps less than 1 inch (25.4 mm) shall be approved as a permanent part of a listed assembly that has been tested under actual backflow conditions with vacuums of 0 to 25 inches of mercury (85 kPa).
603.5.7 Outlets with Hose Attachments. Potable water outlets with hose attachments, other than water heater drains, boiler drains, and clothes washer connections, shall be protected by a nonremovable hose bibbtype backflow preventer, a nonremovable hose bibb-type vacuum breaker, or by an atmospheric vacuum breaker installed not less than 6 inches (152 mm) above the highest point of usage located on the discharge side of the last valve. In climates where freezing temperatures occur, a listed self-draining frost-proof hose bibb with an integral backflow preventer or vacuum breaker shall be used. 603.5.8 Water-Cooled Equipment. Water-cooled compressors, degreasers, or other water-cooled equipment shall be protected by a backflow preventer installed in accordance with the requirements of this chapter. Water-cooled equipment that produces backpressure shall be equipped with the appropriate protection. 603.5.9 Aspirators. Water inlets to water-supplied aspirators shall be equipped with a vacuum breaker installed in accordance with its listing requirements and this chapter. The discharge shall drain through an air gap. Where the tailpiece of a fixture to receive the discharge of an aspirator is used, the air gap shall be located above the flood-level rim of the fixture.
603.5.10 Steam or Hot Water Boilers. Potable water connections to steam or hot water boilers shall be protected from backflow by a double check valve backflow prevention assembly, backflow preventer with intermediate atmospheric vent and pressure reducing valve, or reduced pressure principle backflow prevention assembly in accordance with Table 603.2. Where chemicals are introduced into the system a reduced pressure principle backflow prevention assembly shall be provided in accordance with Table 603.2.
603.5.11 Nonpotable Water Piping. In cases where it is impractical to correct individual cross-connections on the domestic waterline, the line supplying such outlets
shall be considered a nonpotable water line. No drinking or domestic water outlets shall be connected to the nonpotable waterline. Where possible, portions of the nonpotable waterline shall be exposed, and exposed portions shall be properly identified in a manner satisfactory to the Authority Having Jurisdiction. Each outlet on the nonpotable waterline that is permitted to be used for drinking or domestic purposes shall be posted: “CAUTION: NONPOTABLE WATER, DO NOT DRINK.”
[HCD 1 & HCD 2] An international symbol of a glass in a circle with a slash through it shall be provided sim- ilar to that shown in Figure 601.
CRC § 422.1 Medium relevance — show source text
PLUMBING FIXTURES AND FIXTURE FITTINGS
TABLE 422.1 MINIMUM PLUMBING FACILITIES [1]
Each building shall be provided with sanitary facilities, including provisions for persons with disabilities as prescribed by the Department Having Jurisdiction [8] . Table 422.1 applies to new buildings, additions to a building, and changes of occupancy or type in an existing building resulting in increased occupant
load.
For requirements for persons with disabilities, Chapter 11A or 11B of the California Building Code shall be used .
[BSC & DSA-SS] The total occupant load shall be determined in accordance with the California Building Code or Table 4-1 Occupant Load Factor.
Exceptions: (1) [HCD 1-AC & HCD 2] For applications listed in Sections 1.8.2.1.2 and 1.8.2.1.3 regulated by the Department of Housing and Community Development, each building shall be provided with sanitary facilities, including provisions for persons with disabilities as prescribed by the Department. Covered mul- tifamily dwellings required to be accessible to persons with disabilities shall comply with Chapter 11A of the California Building Code. Permanent build- ings in mobilehome parks and special occupancy parks required to be accessible by persons with disabilities, shall comply with Chapter 11B of the California Building Code. (2) [HCD 1] For limited density owner-built rural dwelling sanitary facilities, the type, design and number of facilities as required and approved by the local health official shall be provided to the dwelling sites. It shall not be required that such facilities be located within the dwelling.
TYPE OF
OCCUPANCY2WATER CLOSETS
(FIXTURES PER PERSON)3Col3 URINALS
(FIXTURES
PER
PERSON)4LAVATORIES
(FIXTURES PER PERSON)5Col6 BATHTUBS
OR
SHOWERS
(FIXTURES
PER
PERSON)DRINKING
FOUNTAINS/
FACILITIES
(FIXTURES
PER
PERSON)OTHER6, 7 A-1 Assembly occupancy
(fixed or permanent seat-
ing)- theaters, concert
halls, and auditoriumsMale
1: 1-100
2: 101-200
3: 201-400Female
1: 1-25
2: 26-50
3: 51-100
4: 101-200
6: 201-300
8: 301-400Male
1: 1-200
2: 201-300
3: 301-400
4: 401-600Male
1: 1-200
2: 201-400
3: 401-600
4: 601-750Female
1: 1-100
2: 101-200
4: 201-300
5: 301-500
6: 501-750–– 1: 1-250
2: 251-500
3: 501-7501 service
sink or
laundry sinkA-1 Assembly occupancy
(fixed or permanent seat-
ing)- theaters,CRC § 601.2.1.1 Medium relevance — show source text
601.2.1.1 Approved Submeters. [HCD 1] Sub- meters (or meters) shall be approved in accordance with the Business and Professions Code, Division 5.
601.2.1.2 Submeter Testing. [HCD 1] Submeter (or meter) testing shall be in accordance with the California Code of Regulations, Title 4, Division 9, Chapter 3, Article 1; Civil Code, Division 3, Part 4, Title 5; and Business and Professions Code, Divi- sion 5.
601.2.2 Hot and Cold Water Required. In occupancies where plumbing fixtures are installed for private use, hot water shall be required for bathing, washing, laundry, cooking purposes, dishwashing or maintenance. In occupancies where plumbing fixtures are installed for public use, hot water shall be required for bathing and washing purposes. This requirement shall not supersede the requirements for individual temperature control limitations for public lavatories and public and private bidets, bathtubs, whirlpool bathtubs, and shower control valves.
601.3 Identification of a Potable and Nonpotable Water System. In buildings where potable water and nonpotable water systems are installed, each system shall be clearly identified in accordance with Section 601.3.1 through Section 601.3.5.
601.3.1 Potable Water. Green background with white lettering.
601.3.2 Color and Information. Each system shall be identified with a colored pipe or band and coded with paints, wraps, and materials compatible with the piping.
Except as required by Section 601.3.3, nonpotable water systems shall have a yellow background with black uppercase lettering, with the words “CAUTION: NONPOTABLE WATER, DO NOT DRINK.” Each nonpotable system shall be identified to designate the liquid being conveyed, and the direction of normal flow shall be clearly shown. The minimum size of the letters and length of the color field shall comply with Table 601.3.2.
[HCD 1 & HCD 2] An international symbol of a glass in a circle with a slash through it shall be provided sim- ilar to that shown in Figure 601 for all nonpotable water
systems.
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WATER SUPPLY AND DISTRIBUTION
FIGURE 601
INTERNATIONAL SYMBOL
The background color and required information shall be indicated every 20 feet (6096 mm) but not less than once per room, and shall be visible from the floor level.
601.3.3 Alternate Water Sources. Alternate water source systems shall have a purple (Pantone color No. 512, 522C, or equivalent) background with uppercase lettering and shall be field or factory marked as follows:
(1) Gray water systems shall be marked in accordance with this section with the words “CAUTION: NONPOTABLE GRAY WATER, DO NOT DRINK” in black letters.
CRC § 1605.3.3 Medium relevance — show source text
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.
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CALIFORNIA PLUMBING CODE – MATRIX ADOPTION TABLE
CHAPTER 17 - REFERENCED STANDARDS
(Matrix Adoption Tables are non-regulatory, intended only as an aid to the code user. See Chapter 1 for state agency authority and building applications.)
CPC § 2025 Medium relevance — show source text
The safety requirements provide protection for piping, material, and structures, with provisions for installation practices, removing stress and strain of the pipe, sleeving, and hanger support. The building’s structural stability is protected by the regulations for cutting and notching of structural members.
Chapter 4 Plumbing Fixtures and Fixture Fittings.
This chapter regulates the minimum number of plumbing fixtures of a specific type and quality for each building. The fixtures must be properly installed to be usable by the individuals occupying the building. The quality and design of every fixture must conform to the applicable referenced standard. Compliance with this chapter will result in a building or structure having acceptable plumbing fixtures for the sanitary, hygienic, cleaning, washing, and food preparation needs of the occupants. In addition to ensuring resilient fixtures, the chapter also takes into consideration gender-neutral facilities and contains provisions for privacy compartments.
Chapter 5 Water Heaters.
Chapter 5 regulates the design, approval, installation, and safety devices of fuel burning and other types of water heaters with the combustion air requirements for ventilation and dilution of flue gases for appliances installed in buildings. This chapter does not apply to direct-vent appliances. In addition, this chapter regulates the design, construction, installation, and maintenance of chimneys, vents, and their connections to fuel-burning appliances. Methods to supply combustion air may be supplied from an indoor air supply, outdoor air supply, a combination of indoor and outdoor air supply, mechanical air supply, or an engineered system. Combustion air provisions are based on the number of openings and the total opening size required based on the total energy input rating of the appliance. An acceptable air supply for combustion and ventilation is necessary for the proper operation of fuel-burning appliances. A shortage of combustion air can result in incomplete combustion and the production of poisonous gases, such as carbon monoxide or appliance overheating. Ventilation air provides cooling for the appliance casing and internal controls. Inadequate ventilation of the space in which an appliance is installed can result in increased surrounding temperatures that stress the appliance itself or other appliances in the vicinity.
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FORMAT OF THE UNIFORM PLUMBING CODE
Chapter 6 Water Supply and Distribution.
Chapter 6 regulates the design, material, and installation of water supply and distribution systems, including residential fire sprinklers. The water supply and distribution system is designed to achieve the correct water pressure and flow rates and avoid cross-connections. For fixtures to perform properly, an acceptable supply of potable water is essential to their operation and use. Cross-connections and backflow are ranked as the highest priority because of the long history of recognized health risks posed by cross-connections, outbreaks, or cases of waterborne disease. Piping materials and components are evaluated for their possible effect on the potable water with which they are in contact. The intent is to control the potential adverse health effects produced by indirect additives, products, and materials that come in contact with potable water. When selecting materials for water supply and distribution systems, consider water pressure, water temperature, compatibility with the water supply, durability, support, and sustainability.
CRC § 601.3.3 Medium relevance — show source text
Except as required by Section 601.3.3, nonpotable water systems shall have a yellow background with black uppercase lettering, with the words “CAUTION: NONPOTABLE WATER, DO NOT DRINK.” Each nonpotable system shall be identified to designate the liquid being conveyed, and the direction of normal flow shall be clearly shown. The minimum size of the letters and length of the color field shall comply with Table 601.3.2.
[HCD 1 & HCD 2] An international symbol of a glass in a circle with a slash through it shall be provided sim- ilar to that shown in Figure 601 for all nonpotable water
systems.
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WATER SUPPLY AND DISTRIBUTION
FIGURE 601
INTERNATIONAL SYMBOL
The background color and required information shall be indicated every 20 feet (6096 mm) but not less than once per room, and shall be visible from the floor level.
601.3.3 Alternate Water Sources. Alternate water source systems shall have a purple (Pantone color No. 512, 522C, or equivalent) background with uppercase lettering and shall be field or factory marked as follows:
(1) Gray water systems shall be marked in accordance with this section with the words “CAUTION: NONPOTABLE GRAY WATER, DO NOT DRINK” in black letters.
(2) Reclaimed (recycled) water systems for outdoor applications shall be marked in accordance with this section with the words: “CAUTION: NONPOTABLE RECLAIMED (RECYCLED) WATER, DO NOT DRINK” in black letters.
(3) On-site treated water systems shall be marked in accordance with this section with the words: “CAU TION: ON-SITE TREATED NONPOTABLE WATER, DO NOT DRINK” in black letters.
(4) Rainwater catchment systems shall be marked in accordance with this section with the words: “CAU TION: NONPOTABLE RAINWATER, DO NOT DRINK” in black letters.
Exception: [DWR] For recycled water supply systems that are within or a part of a building, the provisions of Section 1505.7 shall apply.
TABLE 601.3.2
MINIMUM LENGTH OF COLOR FIELD AND SIZE OF LETTERS
OUTSIDE DIAMETER
OF PIPE OR
COVERING
(inches)MINIMUM LENGTH OF
COLOR FIELD
(inches)MINIMUM SIZE OF
LETTERS
(inches)
1⁄2 to 11⁄48 1⁄2
11⁄2 to 28 3⁄4
21⁄2 to 612 11⁄4
8 to 1024 21⁄2
Over 1032 31⁄2 For SI units: 1 inch = 25.4 mm
CRC § 606.6 Medium relevance — show source text
Manufactured water distribution manifolds shall
be in accordance with IAPMO IGC 109.
606.6 Accessible. Required shutoff or control valves shall be accessible.
606.7 Multiple Fixtures. A single control valve shall be installed on a water supply line ahead of an automatic metering valve that supplies a battery of fixtures. 606.8 [OSHPD 1, 1R, 2, 3, 4 & 5] Each riser or branch shall be provided with an accessible sectionalizing valve in hot-and cold-water systems to permit servicing or replace- ment of piping or equipment. Stop valves shall be provided at each fixture. 606.9 Check Valve Required. All systems that circulate water by means of a pump or other mechanical device or method shall have a check valve(s) or equal device(s) installed so as to ensure the direction of flow.
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WATER SUPPLY AND DISTRIBUTION
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606.10 Leak Detection Devices. Where leak detection devices for water supply and distribution are installed, they shall comply with ANSI/CAN/IAPMO Z1349.
607.0 Potable Water Supply Tanks. 607.1 General. Potable water supply tanks shall be installed in accordance with the manufacturer’s installation instructions and supported in accordance with the California Building Code . 607.2 Private Well Water Tanks. Pressurized potable water tanks for private well water systems shall comply with ASSE 1099/WSC-PST 2000.
607.3 Potable Water Tanks. Potable water supply tanks, interior tank coatings, or tank liners intended to supply drinking water shall comply with NSF/ANSI/CAN 61. 607.4 Venting. Tanks used for potable water shall be tightly covered and vented in accordance with the manufacturer’s
installation instructions. Such vent shall be screened with a cor rosion-resistant material of not less than number 24 mesh.
607.5 Overflow. Tanks shall have not less than a 16 square inch (0.01 m [2] ) overflow that is screened with a corrosionresistant material of not less than number 24 mesh.
607.6 Valves. Pressurized tanks shall be provided with a listed pressure-relief valve installed in accordance with the manufacturer’s installation instructions. The relief valve shall be discharged in accordance with Section 608.5. Where a potable water supply tank is located above the fixtures, appliances, or system components it serves, it shall be equipped with a vacuum relief valve that complies with ANSI Z21.22/CSA 4.4.
608.0 Water Pressure, Pressure Regulators, Pres- sure Relief Valves, and Vacuum Relief Valves. 608.1 Inadequate Water Pressure. Where the water pressure in the main or other source of supply will not provide a residual water pressure of not less than 15 pounds force per square inch (psi) (103 kPa), after allowing for friction and other pressure losses, a tank and a pump or other means that will provide said 15 psi (103 kPa) pressure shall be installed. Where fixtures, fixture fittings, or both are installed that, require a residual pressure exceeding 15 psi (103 kPa), that minimum residual pressure shall be provided.
**608.2 Excessive Water Pressure.
CRC § 1.1 Medium relevance — show source text
SECTION R309—AUTOMATIC SPRINKLER SYSTEMS
R309.1 Townhouse automatic sprinkler systems. An automatic sprinkler system shall be installed in townhouses.
Exception: An automatic sprinkler system shall not be required where additions or alterations are made to existing townhouses that do not have an automatic sprinkler system installed.
R309.1.1 Design and installation. Automatic sprinkler systems for townhouses shall be designed and installed in accordance with Section R309 or NFPA 13D.
R309.2 One- and two-family dwellings automatic sprinkler systems. An automatic sprinkler system shall be installed in one- and two-family dwellings.
Exceptions:
- An automatic sprinkler system shall not be required for additions or alterations to existing buildings that are not already provided with a sprinkler system. 2. Accessory Dwelling Unit, provided that all of the following are met: 2.1. The unit meets the definition of an Accessory Dwelling Unit as defined in the Government Code Section 65852.2. 2.2. The existing primary residence does not have automatic fire sprinklers. 2.3. The accessory detached dwelling unit does not exceed 1,200 square feet in size. 2.4. The unit is on the same lot as the primary residence.
R309.2.1 Design and installation. Automatic sprinkler systems shall be designed and installed in accordance with Section R309 or NFPA 13D.
R309.3 Dwelling unit automatic sprinkler systems.
R309.3.1 General. The design and installation of automatic sprinkler systems shall be in accordance with NFPA 13D or Section R309.3, which shall be considered to be equivalent to NFPA 13D. Partial automatic sprinkler systems shall be permitted to be installed only in buildings not required to be equipped with an automatic sprinkler system. Section R309.3 shall apply to standalone and multipurpose wet-pipe sprinkler systems that do not include the use of antifreeze. A multipurpose automatic sprinkler system shall provide domestic water to both fire sprinklers and plumbing fixtures. A stand-alone automatic sprinkler system shall be separate and independent from the water distribution system.
R309.3.1.1 Backflow protection. A backflow preventer shall not be required to separate a sprinkler system from the water distri- bution system, provided that: 1. The system complies with NFPA 13D or Section R309; 2. Piping materials are suitable for potable water in accordance with the California Plumbing Code; and 3. The system does not contain antifreeze or have a fire department connection.
R309.3.1.2 Required sprinkler locations. Sprinklers shall be installed to protect all areas of a dwelling unit.
CRC § 3.5.2 Medium relevance — show source text
pump.
R309.3.5.2 Required capacity. The water supply shall have the capacity to provide the required design flow rate for sprinklers for a period of time as follows:
- Seven minutes for dwelling units one story in height and less than 2,000 square feet (186 m [2] ) in area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies and patios shall not be included.
- Ten minutes for dwelling units two or more stories in height or equal to or greater than 2,000 square feet (186 m [2] ) in area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies and patios shall not be included.
R309.3.5.2.1 Where a well system, a water supply tank system or a combination thereof is used, the configuration for the system shall be one of the following: 1. The water supply shall serve both domestic and fire sprinkler systems. Any combination of well capacity and tank storage shall be permitted to meet the capacity requirement. 2. A stand-alone tank is permitted if the following conditions are met: 2.1. The pump shall be connected to a 220-volt circuit breaker shared with a common household appliance (e.g., range, oven, dryer), 2.2. The pump shall be a stainless steel 240-volt pump, 2.3. A valve shall be provided to exercise the pump. The discharge of the exercise valve shall be piped to the tank, and
2.4. A sign shall be provided stating “Valve must be opened monthly for 5 minutes.” 2.5. A means for automatically refilling the tank level so that the tank capacity will meet the required water supply duration in minutes shall be provided.
R309.3.5.3 Connections to automatic fire sprinkler systems. The potable water supply to automatic fire sprinkler shall be protected against backflow by a double check backflow prevention assembly, a double check fire protection backflow prevention assembly, a reduced pressure principle backflow prevention assembly or a reduced pressure principle fire protection backflow prevention assembly.
Exception: Where permitted by Section R309.3.1.1, backflow protection for the water supply system shall not be required.
R309.3.5.3.1 Additives or nonpotable source. Where systems contain chemical additives or antifreeze, or where systems are connected to a nonpotable secondary water supply, the potable water supply shall be protected against backflow by a reduced pressure principle backflow prevention assembly or a reduced pressure principle fire protection backflow prevention assembly. Where chemical additives or antifreeze is added to only a portion of an automatic sprinkler or standpipe system, the reduced pressure principle fire protection backflow preventer shall be permitted to be located so as to isolate that portion of the system.
R309.3.6 Pipe sizing. The piping to sprinklers shall be sized for the flow required by Section R309.3.4.2. The flow required to supply the plumbing fixtures shall not be required to be added to the sprinkler design flow.
CRC § 3.4.1.2 Medium relevance — show source text
R309.3.4.1.2 Ceiling configurations with special sprinkler listings. For ceiling configurations not specified in Section R309.3.4.1.1 the manufacturer’s published flow rate for sprinklers that have been listed for protection of such configurations shall be used.
R309.3.4.1.3 Other ceiling configurations. For ceiling configurations not addressed by Section R309.3.4.1.1 or R309.3.4.1.2 the flow rate shall be subject to approval by the building official.
R309.3.4.2 System design flow rate. The design flow rate for the system shall be based on the following:
The design flow rate for a room having only one sprinkler shall be the flow rate required for that sprinkler, as determined by Section R309.3.4.1.
The design flow rate for a room having two or more sprinklers shall be determined by identifying the sprinkler in that room with the highest required flow rate, based on Section R309.3.4.1, and multiplying that flow rate by 2.
Where the sprinkler manufacturer specifies different criteria for ceiling configurations that are not smooth, flat and horizontal, the required flow rate for that room shall comply with the sprinkler manufacturer’s instructions.
The design flow rate for the automatic sprinkler system shall be the flow required by the room with the largest flow rate, based on Items 1, 2 and 3.
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- For the purpose of this section, it shall be permissible to reduce the design flow rate for a room by subdividing the space into two or more rooms, where each room is evaluated separately with respect to the required design flow rate. Each room shall be bounded by walls and a ceiling. Openings in walls shall have a lintel not less than 8 inches (203 mm) in depth and each lintel shall form a solid barrier between the ceiling and the top of the opening.
R309.3.5 Water supply. The water supply shall provide not less than the required design flow rate for sprinklers in accordance with Section R309.3.4.2 at a pressure not less than that used to comply with Section R309.3.6. Where a water supply serves both domestic and fire sprinkler systems, 5 gpm (19 L/min) shall be added to the sprinkler system demand at the point where the systems are connected, to determine the size of common piping and the size of the total water supply requirements where no provision is made to prevent flow into the domestic water system upon operation of a sprinkler. For multipurpose piping systems, the 5 gpm (19 L/min) demand shall be added at the domestic connection nearest the design area. This demand may be split between two domestic connec- tions at 2.5 gpm (10 L/min) each.
R309.3.5.1 Water supply from individual sources. Where a dwelling unit water supply is from a tank system, a private well system or a combination of these, the available water supply shall be based on the minimum pressure control setting for the
pump.
CRC § 3.5 Medium relevance — show source text
BUILDING PLANNING
- For the purpose of this section, it shall be permissible to reduce the design flow rate for a room by subdividing the space into two or more rooms, where each room is evaluated separately with respect to the required design flow rate. Each room shall be bounded by walls and a ceiling. Openings in walls shall have a lintel not less than 8 inches (203 mm) in depth and each lintel shall form a solid barrier between the ceiling and the top of the opening.
R309.3.5 Water supply. The water supply shall provide not less than the required design flow rate for sprinklers in accordance with Section R309.3.4.2 at a pressure not less than that used to comply with Section R309.3.6. Where a water supply serves both domestic and fire sprinkler systems, 5 gpm (19 L/min) shall be added to the sprinkler system demand at the point where the systems are connected, to determine the size of common piping and the size of the total water supply requirements where no provision is made to prevent flow into the domestic water system upon operation of a sprinkler. For multipurpose piping systems, the 5 gpm (19 L/min) demand shall be added at the domestic connection nearest the design area. This demand may be split between two domestic connec- tions at 2.5 gpm (10 L/min) each.
R309.3.5.1 Water supply from individual sources. Where a dwelling unit water supply is from a tank system, a private well system or a combination of these, the available water supply shall be based on the minimum pressure control setting for the
pump.
R309.3.5.2 Required capacity. The water supply shall have the capacity to provide the required design flow rate for sprinklers for a period of time as follows:
- Seven minutes for dwelling units one story in height and less than 2,000 square feet (186 m [2] ) in area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies and patios shall not be included.
- Ten minutes for dwelling units two or more stories in height or equal to or greater than 2,000 square feet (186 m [2] ) in area. For the purpose of determining the area of the dwelling unit, the area of attached garages and attached open carports, porches, balconies and patios shall not be included.
R309.3.5.2.1 Where a well system, a water supply tank system or a combination thereof is used, the configuration for the system shall be one of the following: 1. The water supply shall serve both domestic and fire sprinkler systems. Any combination of well capacity and tank storage shall be permitted to meet the capacity requirement. 2. A stand-alone tank is permitted if the following conditions are met: 2.1. The pump shall be connected to a 220-volt circuit breaker shared with a common household appliance (e.g., range, oven, dryer), 2.2. The pump shall be a stainless steel 240-volt pump, 2.3. A valve shall be provided to exercise the pump. The discharge of the exercise valve shall be piped to the tank, and
CRC § 3.5.3 Medium relevance — show source text
2.4. A sign shall be provided stating “Valve must be opened monthly for 5 minutes.” 2.5. A means for automatically refilling the tank level so that the tank capacity will meet the required water supply duration in minutes shall be provided.
R309.3.5.3 Connections to automatic fire sprinkler systems. The potable water supply to automatic fire sprinkler shall be protected against backflow by a double check backflow prevention assembly, a double check fire protection backflow prevention assembly, a reduced pressure principle backflow prevention assembly or a reduced pressure principle fire protection backflow prevention assembly.
Exception: Where permitted by Section R309.3.1.1, backflow protection for the water supply system shall not be required.
R309.3.5.3.1 Additives or nonpotable source. Where systems contain chemical additives or antifreeze, or where systems are connected to a nonpotable secondary water supply, the potable water supply shall be protected against backflow by a reduced pressure principle backflow prevention assembly or a reduced pressure principle fire protection backflow prevention assembly. Where chemical additives or antifreeze is added to only a portion of an automatic sprinkler or standpipe system, the reduced pressure principle fire protection backflow preventer shall be permitted to be located so as to isolate that portion of the system.
R309.3.6 Pipe sizing. The piping to sprinklers shall be sized for the flow required by Section R309.3.4.2. The flow required to supply the plumbing fixtures shall not be required to be added to the sprinkler design flow.
R309.3.6.1 Method of sizing pipe. Piping supplying sprinklers shall be sized using the prescriptive method in Section R309.3.6.2 or by hydraulic calculation in accordance with NFPA 13D. The minimum pipe size from the water supply source to any sprinkler shall be [3] / 4 inch (19 mm) nominal. Threaded adapter fittings at the point where sprinklers are attached to the piping shall be not less than [1] / 2 inch (13 mm) nominal.
R309.3.6.2 Prescriptive pipe sizing method. Pipe shall be sized by determining the available pressure to offset friction loss in piping and identifying a piping material, diameter and length using the equation in Section R309.3.6.2.1 and the procedure in Section R309.3.6.2.2 .
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BUILDING PLANNING
TABLE R309.3.6.2(1)—WATER SERVICE PRESSURE LOSS (PL ) a, b
svcCol2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 Col11 Col12 Col13 FLOW
RATEc
(gpm)3/4-INCH WATER SERVICE
PRESSURE LOSS (psi)3/4-INCH WATER SERVICE
PRESSURE LOSS (psi)3/4-INCH WATER SERVICE
PRESSURE LOSS (psi)**3/4-INCH CRC § 3.4.2. Medium relevance — show source text
Flow rate from Section_ R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section R309.3.4.2._|3-48 2025 CALIFORNIA RESIDENTIAL CODE
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TABLE R309.3.6.2(6)—ALLOWABLE PIPE LENGTH FOR 3/-INCH CPVC PIPE
4Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 Col11 Col12 SPRINKLER
FLOW RATEa
(gpm)WATER
DISTRIBUTION SIZE
(inch)AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) **AVAILABLE CRC § 3.4.2 Medium relevance — show source text
Flow rate from Section_R309.3.4.2_.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section_R309.3.4.2_.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section_R309.3.4.2_.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section_R309.3.4.2_.|For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.963 L/s.
a. Flow rate from Section_R309.3.4.2_.|3-50 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
BUILDING PLANNING
TABLE R309.3.6.2(8)—ALLOWABLE PIPE LENGTH FOR 3/-INCH PEX AND PE-RT TUBING
4Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 Col11 Col12 SPRINKLER
FLOW RATEa
(gpm)WATER
DISTRIBUTION SIZE
(inch)AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) SPRINKLER
FLOW RATEa
(gpm)WATER
DISTRIBUTION SIZE
(inch)15 20 25 30 35 40 45 50 55 60 SPRINKLER
FLOW RATEa
(gpm)WATER
DISTRIBUTION SIZE
(inch)Allowable length of pipe from service valve to farthest sprinkler (feet) Allowable length of pipe from service valve to farthest sprinkler (feet) Allowable length of pipe from service valve to farthest sprinkler (feet) Allowable length of pipe from service valve to farthest sprinkler (feet) **Allowable length of pipe CRC § 6.2 Medium relevance — show source text
Table P2904.6.2(2) establishes conservative values for water meter pressure loss or installations where the water meter loss is unknown. Where the actual water meter pres-
sure loss is published and available from the meter manufacturer,PLm shall be the published pressure loss for the selected meter.
b. Flow rate from Section P2904.4.2. Add 5 gpm to the flow rate required by Section_R309.3.4.2_ where the water service pipe supplies more than one dwelling.|For SI: 1 inch = 25.4 mm, 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 0.063 L/s.
NP = Not permitted unless the actual water meter pressure loss is known.
a. Table P2904.6.2(2) establishes conservative values for water meter pressure loss or installations where the water meter loss is unknown. Where the actual water meter pres-
sure loss is published and available from the meter manufacturer,PLm shall be the published pressure loss for the selected meter.
b. Flow rate from Section P2904.4.2. Add 5 gpm to the flow rate required by Section_R309.3.4.2_ where the water service pipe supplies more than one dwelling.|3-46 2025 CALIFORNIA RESIDENTIAL CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
BUILDING PLANNING
TABLE R309.3.6.2(3)—ELEVATION LOSS (PL)
eCol2 ELEVATION
(feet)PRESSURE LOSS
(psi)5 2.2 10 4.4 15 6.5 20 8.7 25 10.9 30 13 35 15.2 40 17.4 For SI: 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa. For SI: 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa. TABLE R309.3.6.2(4)—ALLOWABLE PIPE LENGTH FOR 3/-INCH TYPE M COPPER WATER TUBING
4Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 Col11 Col12 SPRINKLER
FLOW RATEa
(gpm)WATER
DISTRIBUTION SIZE
(inch)AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) AVAILABLE PRESSURE—****Pt(psi) SPRINKLER
FLOW RATEa
(gpm)WATER
**DISTRIBUTIONCRC § 2.1 Medium relevance — show source text
R309.2.1 Design and installation. Automatic sprinkler systems shall be designed and installed in accordance with Section R309 or NFPA 13D.
R309.3 Dwelling unit automatic sprinkler systems.
R309.3.1 General. The design and installation of automatic sprinkler systems shall be in accordance with NFPA 13D or Section R309.3, which shall be considered to be equivalent to NFPA 13D. Partial automatic sprinkler systems shall be permitted to be installed only in buildings not required to be equipped with an automatic sprinkler system. Section R309.3 shall apply to standalone and multipurpose wet-pipe sprinkler systems that do not include the use of antifreeze. A multipurpose automatic sprinkler system shall provide domestic water to both fire sprinklers and plumbing fixtures. A stand-alone automatic sprinkler system shall be separate and independent from the water distribution system.
R309.3.1.1 Backflow protection. A backflow preventer shall not be required to separate a sprinkler system from the water distri- bution system, provided that: 1. The system complies with NFPA 13D or Section R309; 2. Piping materials are suitable for potable water in accordance with the California Plumbing Code; and 3. The system does not contain antifreeze or have a fire department connection.
R309.3.1.2 Required sprinkler locations. Sprinklers shall be installed to protect all areas of a dwelling unit.
Exceptions:
- Attics, crawl spaces and normally unoccupied concealed spaces that do not contain fuel-fired appliances do not require sprinklers. In attics, crawl spaces and normally unoccupied concealed spaces that contain fuel-fired equipment, a sprinkler shall be installed above the equipment; however, sprinklers shall not be required in the remainder of the space.
- Clothes closets, linen closets and pantries not exceeding 24 square feet (2.2 m [2] ) in area, with the smallest dimension not greater than 3 feet (915 mm) and having wall and ceiling surfaces of gypsum board.
- Bathrooms not more than 55 square feet (5.1 m [2] ) in area.
- Garages; carports; exterior porches; unheated entry areas, such as mud rooms, that are adjacent to an exterior door; and similar areas.
R309.3.2 Sprinklers. Sprinklers shall be new listed residential sprinklers and shall be installed in accordance with the sprinkler manufacturer’s instructions.
R309.3.2.1 Temperature rating and separation from heat sources. Except as provided for in Section R309.3.2, sprinklers shall have a temperature rating of not less than 135°F (57°C) and not more than 225°F (107°C). Sprinklers shall be separated from heat sources as required by the sprinkler manufacturer’s installation instructions.
R309.3.2.2 Intermediate temperature sprinklers. Sprinklers shall have an intermediate temperature rating not less than 175°F (79°C) and not more than 225°F (107°C) where installed in the following locations:
Directly under skylights, where the sprinkler is exposed to direct sunlight.
In attics.
In concealed spaces located directly beneath a roof.
Within the distance to a heat source as specified in Table R309.3.2.2 .
CRC § 4-1 Medium relevance — show source text
The daily use number shall be increased to three if urinals are not installed in the room.
2. Refer to Table 4-1, Chapter 4, 2025_California Plumbing Code_, for occupant load factors.
a. Shower use by occupants depends on the type of use of a building or portion of a building, e.g., total occupant load for a health club, but only a fraction of the occupants
in an office building as determined by the anticipated number of users.
b. Kitchen faucet use is determined by the occupant load of the area served by the fixture.
3. Use worksheet WS-1 to calculate baseline water use.
4. Floor-mounted urinals @ 0.5 GPF or wall-mounted urinals @ 0.125 GPF.|1. The daily use number shall be increased to three if urinals are not installed in the room.
2. Refer to Table 4-1, Chapter 4, 2025_California Plumbing Code_, for occupant load factors.
a. Shower use by occupants depends on the type of use of a building or portion of a building, e.g., total occupant load for a health club, but only a fraction of the occupants
in an office building as determined by the anticipated number of users.
b. Kitchen faucet use is determined by the occupant load of the area served by the fixture.
3. Use worksheet WS-1 to calculate baseline water use.
4. Floor-mounted urinals @ 0.5 GPF or wall-mounted urinals @ 0.125 GPF.|1. The daily use number shall be increased to three if urinals are not installed in the room.
2. Refer to Table 4-1, Chapter 4, 2025_California Plumbing Code_, for occupant load factors.
a. Shower use by occupants depends on the type of use of a building or portion of a building, e.g., total occupant load for a health club, but only a fraction of the occupants
in an office building as determined by the anticipated number of users.
b. Kitchen faucet use is determined by the occupant load of the area served by the fixture.
3. Use worksheet WS-1 to calculate baseline water use.
4. Floor-mounted urinals @ 0.5 GPF or wall-mounted urinals @ 0.125 GPF.|1. The daily use number shall be increased to three if urinals are not installed in the room.
2. Refer to Table 4-1, Chapter 4, 2025_California Plumbing Code_, for occupant load factors.
a. Shower use by occupants depends on the type of use of a building or portion of a building, e.g., total occupant load for a health club, but only a fraction of the occupants
in an office building as determined by the anticipated number of users.
b. Kitchen faucet use is determined by the occupant load of the area served by the fixture.
3. Use worksheet WS-1 to calculate baseline water use.
4. Floor-mounted urinals @ 0.5 GPF or wall-mounted urinals @ 0.125 GPF.|A5.303.2.3.1 Tier 1 – 12-percent savings. A schedule of plumbing fixtures and fixture fittings that will reduce the overall use of potable water within the building by 12 percent shall be provided.
Frequently asked questions
Do I always have to provide hot water to fixtures?
Hot water is required where fixtures are installed for private use for bathing, washing, laundry, cooking, dishwashing or maintenance; for public use fixtures, hot water is required for bathing and washing. See § 601.2.2.
If my house uses a well plus a storage tank, how do I meet sprinkler duration?
Use the required duration (7 or 10 minutes) to size storage and pump configuration; the code permits combinations of well capacity and tank storage or a stand‑alone tank subject to the conditions in § R309.3.5.2.1.
If I install a water softener, will that affect my sprinkler system?
Devices that restrict flow or reduce pressure can affect sprinkler performance. The R309 rules require that device pressure losses be accounted for in sizing or be bypassed, and the owner must be warned about adding flow‑restricting devices. § R309.3.6.2 Step 4 and § R309.3.7.
Can I use captured rainwater for flushing toilets and still call it potable?
No — rainwater and other alternate sources are nonpotable unless treated and approved; the code allows alternate sources under Chapter 15 but requires clear identification and cross‑connection protection. § 601.2 Exception (4) and § 601.3.
Who decides when the Authority Having Jurisdiction can waive requirements?
The AHJ (local building official) has the authority to determine necessity for safety and sanitation and to grant exceptions where the code allows (see the exceptions to § 601.2 and related sections).
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