Do I have to use Appendix A for every water‑supply calculation?

No — systems that meet the conditions in §610.4 may be sized from Table 610.4; otherwise the sizing procedure in Appendix A (or other approved methods in §610.5) is required for hydraulic calculations.

Must pressure losses from filters, backflow preventers and softeners be included?

Yes — §610.2 requires that pressure losses through meters, valves, water‑treating equipment and backflow prevention devices be included in system pressure‑loss calculations.

How are medical gas systems sized for flow and pressure loss?

Medical gas systems use the sizing procedure in §1323.1.5: determine total flow and fixture/inlet counts, apply diversity factors, compute equivalent lengths and per‑section pressure loss from the tabulated pressure‑loss tables, and ensure total loss to each outlet does not exceed the listed limits.

Sizing, Pressure and Flow Calculations

Grounded in the retrieved California Plumbing Code — click a citation to read the verbatim passage:

CPC § 1323.1.4 High relevance — show source text

1323.1.4 Maximum Demand. Where the maximum demand for each medical gas or vacuum system does not exceed the values in Table 1323.1.4(1) through Table 1323.1.4(6), the size of pipe of each section of the system shall be determined in accordance with Section 1323.1.5. The size for systems beyond the range of Table 1323.1.4(1) through Table 1323.1.4(6) shall be determined in accordance with Section 1323.1.6.

1323.1.5 Sizing Procedures. The size of each section of pipe in a system within the range of Table 1323.1.4(1) through Table 1324.1.4(6) shall be determined in accordance with the following:

(1) Determine the total flow rate and number of outlets or inlets for each section of pipe in accordance with Table 1305.2 and Table 1305.3.

(2) Measure the length of the section of pipe to each station outlet or inlet on the system. Multiply the measured pipe length by 1.5 (150 percent), to account for the number of fittings in the system, to determine the pipe equivalent length.

(3) Beginning with the most remote outlet or inlet, multiply the total flow rate by the diversity factor specified in Table 1323.1.5(1) for each section of pipe to determine the sizing flow rate for the piping.

(4) Select Table 1323.1.4(1) through Table 1324.1.4(6) based on the medical gas or vacuum being transported through the piping.

(5) Select an estimated pipe size for determining the system pressure loss. Multiply the pipe equivalent length, for a given section of pipe, by the pressure loss for the sizing flow rate in the applicable table. Divide that number by 100 to determine the system pressure loss for the section of pipe.

(6) Add the pressure loss for each section of piping, from the source equipment location to the outlet or

inlet, to determine the total system pressure loss to each outlet or inlet. The total system pressure loss in the piping to each outlet or inlet shall not exceed the values specified in Table 1323.1.5(2).

TABLE 1323.1.5(1) SYSTEM SIZING – FLOW REQUIREMENTS FOR STATION OUTLETS AND INLETS [1]

NUMBER OF OUTLETS AND INLETS TERMINAL UNITS PER FACILITY	DIVERSITY PERCENTAGE OF AVERAGE FLOW PER OUTLETS AND INLETS TERMINAL UNITS	MINIMUM PERMISSIBLE SYSTEM FLOW OF ALL PRESSURIZED MEDICAL GAS SYSTEMS2 (standard cubic feet per minute)
1–10	100%	Actual Demand
11–25	75%	7.0
26–50	50%	13.1
51–100	50%	17.5

Notes: 1 Flow rates of station outlets and inlets in accordance with Table 1305.2. 2 The minimum system flow is the average outlets and inlets flow times the number of station outlets and inlets times the diversity percentage.

TABLE 1323.1.5(2) MAXIMUM PERMITTED PRESSURE LOSS IN

CPC § 4.1 High relevance — show source text
This Standard refers to the following publications, and where such reference is made, it shall be to the current edition of those publications, including all amendments published thereto.

IAPMO/ANSI UPC-1 Uniform Plumbing Code

3 Abbreviations

The following abbreviations apply in this Standard:

PVC — polyvinyl chloride

4 General

4.1 Thrust Blocking for Rubber Gasket Joints

In lines with rubber gasketed joints, thrust blocks shall be installed at all locations including:

(a) Changes in direction, as at tees and bends

(b) Changes in size, as at reducers

(c) Stops, as at dead ends

(d) Valves, where thrusts may be expected.

Note: See examples in Figure 1. 4.2 Sizing

Piping shall be sized in accordance with the applicable code or jurisdictional requirements.

Note: For example, Appendix A, “Recommended Rules for Sizing the Water Supply System”, or Section 610.0, “Size of Potable Water Piping” of IAPMO/ANSI UPC-1 may be use for sizing pipe.

4.3 Flow Velocity

Flow velocity shall not exceed 8 fps (2.4 m/s) for PVC pipe or 10 fps (3m/s) for other pipe materials.

4.4 Deflection

Elastomeric gasketed pipe may be deflected in accordance with the manufacturer’s recommendations pro

2025 CALIFORNIA PLUMBING CODE 463

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

IS 33

vided that it shall not be permanently staked or blocked to maintain this deflection.

4.5 Maximum Working Pressure

The pipe and fitting system shall be designed for the maximum working pressure in accordance with Table 1.

5 Thrust Blocking Sizing and Calculations

5.1 Sizes

Thrust block sizes shall be based on the maximum line pressure, pipe size and the safe bearing load of the soil.

5.2 Calculation Examples

5.2.1 Thrust

5.2.1.1 Example 1

From Table 2, Thrust at Fittings in pounds at 100 psi of Water Pressure, the thrust for a NPS 4 Dead End Tee at a pressure of 100 psi is 1620 lb.

5.2.1.2 Example 2

The thrust for an NPS 4, Dead End Tee, at a pressure of 150 psi is 2430 lb or 1.5 times the thrust found in Table 2.

The calculation is as follows:

(a) The thrust from Table 2, for an NPS 4, Dead End Tee, at 100 psi, is 1,620 lb.

(b) The actual pressure of the system is 150 psi.

(c) Divide the actual pressure by the table pressure or 150 psi/100 psi is 1.5.

(d) Multiply the thrust from Table 2, for an NPS 4, Dead End Tee, at 100 psi, times the ratio of the actual/table pressure, or 1.5 times 1620 lb for a thrust of 2430 lb.

5.2.1.3 Example 3
CPC § 2025 High relevance — show source text
Appendix A Recommended Rules for Sizing the Water Supply System.

Appendix A provides a method of sizing the water supply and distribution system that provides precise calculations to establish the proper pressures and flow to the system’s fixtures. The goal of sizing the system is to deliver an acceptable volume of water to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; provide satisfactory water pressure to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; and to prevent excessive water velocity during maximum flow conditions.

Appendix B Explanatory Notes on Combination Waste and Vent Systems.

Appendix B contains general guidelines for the design and installation of combination waste and vent systems. These systems are designed for waste piping and are purposely oversized to serve as both a waste and vent pipe to avoid excessive pneumatic effects at fixture drains.

Appendix C Alternate Plumbing Systems.

The intent of this appendix is to provide clarification of procedures for the design and approval of engineered plumbing systems, alternate materials, and equipment that are not specifically covered in other parts of the code. Alternative methods are allowed to be used where approved by the authority having jurisdiction. Approval of alternatives is based on a demonstration showing that the method or material used is at least equivalent in strength, deflection, and capacity to that provided by the prescriptive methods and materials.

Appendix D Sizing Storm Water Drainage Systems.

Appendix D provides general guidelines for the sizing of stormwater drainage systems. There are two pieces of information that must always be a given. They are the roof size and the rate of rainfall for the area.

2025 CALIFORNIA PLUMBING CODE xvii

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

FORMAT OF THE UNIFORM PLUMBING CODE

Appendix E Manufactured/Mobile Home Parks and Recreational Vehicle Parks.

The provisions of this appendix apply to the plumbing and drainage systems of mobile home and recreational vehicle parks. These provisions also apply to the use, maintenance, and installation for supplying fuel gas, water, electricity, and disposal of sewage from accessory buildings or structures, and building components.

Appendix F Firefighter Breathing Air Replenishment Systems.

Appendix F provides guidance on installing firefighter breathing air replenishment systems. System components include outside fire department connection panel, interior air fill panel or station, interconnected piping distribution system and pressure monitoring switch. Fire departments access the system through an outside connection panel and are able to pump air into the system. The firefighters inside the structure access the system at fill stations that are found throughout the building. The piping distribution system is made from stainless tubing or other approved materials. It delivers compressed air to the building’s interior air-fill stations and interior air-fill panels. The tubing also acts as a conduit in the interior of the building between the outside connection panel and the air storage system. If the system becomes over-pressurized, the air monitoring system also acts as a pressure relief. A system isolation valve is placed alongside each interior air fill station and interior air fill panel to isolate the system.

Appendix G Sizing of Venting Systems.

Appendix G provides added information on the sizing of gas vents. This appendix is useful to the end user for the proper sizing of venting systems. A series of examples are given that show how to use the tables and other requirements of Chapter 5.

Appendix H Private Sewage Disposal Systems.

CPC § 304.8 Medium relevance — show source text

For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm, 1 cubic foot per hour = 0.0283m [3] /h, 1 pound-force per square inch = 6.8947 kPa, 1 inch water column

= 0.249 kPa

Notes: 1 CTS = Copper tube size. 2 Table entries are rounded to 3 significant digits. 3 NA means a flow of less than 10 ft 3 /h (0.283 m 3 /h).

For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm, 1 cubic foot per hour = 0.0283m [3] /h, 1 pound-force per square inch = 6.8947 kPa, 1 inch water column

= 0.249 kPa

Notes: 1 CTS = Copper tube size. 2 Table entries are rounded to 3 significant digits. 3 NA means a flow of less than 10 ft 3 /h (0.283 m 3 /h).

258 2025 CALIFORNIA PLUMBING CODE

FUEL GAS PIPING

TABLE 1215.2(24) SCHEDULE 40 METALLIC PIPE [NFPA 54: TABLE 6.3.1(a)]*	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10
						GAS:	GAS:	UNDILUTED PROPANE	UNDILUTED PROPANE
						INLET PRESSURE:	INLET PRESSURE:	10.0 psi	10.0 psi
						PRESSURE DROP:	PRESSURE DROP:	1.0 psi	1.0 psi
						SPECIFIC GRAVITY:	SPECIFIC GRAVITY:	1.50	1.50
INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	INTENDED USE: PIPE SIZING BETWEEN FIRST STAGE (HIGH PRESSURE) REGULATOR AND SECOND STAGE (LOW PRESSURE) REGULATOR	**INTENDED

CPC § 1701.1 Medium relevance — show source text
Chapter 16 Nonpotable Rainwater Catchment Systems.

Chapter 16 regulates nonpotable rainwater catchment systems that include irrigation; toilet and urinal flushing with proper treatment; provisions where permits are required; maintenance of alternate water sources; and minimum water quality. This chapter provides guidance on how to optimize rainwater use while ensuring there is a decrease of risk to consumers from poor design, installation, and maintenance. Rainwater harvesting is the process of capturing, channeling, and storing water runoff for later use. Most systems are constructed of three principal components: the catchment area, the collection device, and the conveyance system.

Chapter 17 Referenced Standards.

Chapter 17 provides two comprehensive tables with referenced standards. The standards listed in Table 1701.1 are applied as indicated in the applicable reference section(s). A list of additional approved standards, publications, practices, and guides that are not referenced in specific sections appear in Table 1701.2.

Referenced standards set forth specific details of accepted practices, materials specifications, or test methods in many specialized applications. Standards provide an efficient method of conveying complex information and specifications on the performance requirements for materials, products, systems, application, and installation. The manner and purpose for a standard’s use and, in turn, code compliance, must be definitive in all references to the standard. If the standard is intended to be a requirement for judging code compliance, the code must state its intent for use. The standard should adequately address a defined need and at the same time specify the minimum performance requirements, technical characteristics and methods of testing, and required test results.

The referenced standards tables are organized in a manner that makes it easy to find specific standards in alphabetical order, and by acronym of the publishing agency of the standard. The tables list the title of the standard, the edition, and any addenda. Contact information for each publishing agency is provided at the end of the chapter.

Appendix A Recommended Rules for Sizing the Water Supply System.

Appendix A provides a method of sizing the water supply and distribution system that provides precise calculations to establish the proper pressures and flow to the system’s fixtures. The goal of sizing the system is to deliver an acceptable volume of water to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; provide satisfactory water pressure to the most hydraulically remote fixture during minimum pressure and maximum flow conditions; and to prevent excessive water velocity during maximum flow conditions.

Appendix B Explanatory Notes on Combination Waste and Vent Systems.

Appendix B contains general guidelines for the design and installation of combination waste and vent systems. These systems are designed for waste piping and are purposely oversized to serve as both a waste and vent pipe to avoid excessive pneumatic effects at fixture drains.

Appendix C Alternate Plumbing Systems.

The intent of this appendix is to provide clarification of procedures for the design and approval of engineered plumbing systems, alternate materials, and equipment that are not specifically covered in other parts of the code. Alternative methods are allowed to be used where approved by the authority having jurisdiction. Approval of alternatives is based on a demonstration showing that the method or material used is at least equivalent in strength, deflection, and capacity to that provided by the prescriptive methods and materials.

Appendix D Sizing Storm Water Drainage Systems.

Appendix D provides general guidelines for the sizing of stormwater drainage systems. There are two pieces of information that must always be a given. They are the roof size and the rate of rainfall f
CPC § 1.811 Medium relevance — show source text
36|1.811|0.346|0.087| |14.12|2.298|0.438|0.110| |15.89|2.837|0.539|0.135| |17.66|3.456|0.650|0.163| |19.42|–|0.771|0.193| |21.19|–|0.900|0.225| |22.95|–|1.038|0.260| |24.72|–|1.185|0.295| |28.25|–|1.505|0.375| |31.78|–|1.859|0.463| |35.31|–|2.247|0.559| |38.84|–|2.667|0.663| |42.37|–|3.121|0.775| |45.90|–|3.607|0.895| |49.43|–|4.125|1.022| |52.97|–|–|1.157| |56.50|–|–|1.299| |60.03|–|–|1.449| |63.56|–|–|1.607| |67.09|–|–|1.772| |70.62|–|–|1.944| |81.21|–|–|2.503| |91.81|–|–|3.127| |102.40|–|–|3.813|

For SI units: 1 standard cubic foot per minute = 28.32 SLPM, 1 inch = 25 mm, 1 foot = 304.8 mm, 1 pound-force per square inch = 6.8947 kPa

Notes: 1 Based on pressure of 14.7 psig (101 kPa) at 68°F (20°C). 2 Based on pressure of 55 psig (379 kPa) at 68°F (20 °C).

2025 CALIFORNIA PLUMBING CODE 291

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICAL VACUUM SYSTEMS

TABLE 1323.1.4(5) PRESSURE LOSS FOR VACUUM (continued)
CPC § 610.3 Medium relevance — show source text
No water filter, water softener, backflow prevention device, or similar device regulated by this code shall be installed in a potable water supply piping where the installation of such device produces an excessive pressure drop in such water supply piping. In the absence of specific pressure drop information, the diameter of the inlet or outlet of such device or its connecting piping shall be not less than the diameter of such water distribution piping to the fixtures served by the device.

156 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

WATER SUPPLY AND DISTRIBUTION

Such devices shall be of a type approved by the Authority Having Jurisdiction and shall be tested for flow rating and pressure loss by an approved laboratory or recognized testing agency to standards consistent with the intent of this chapter. 610.3 Quantity of Water. The quantity of water required to be supplied to every plumbing fixture shall be represented by fixture units, as shown in Table 610.3. Equivalent fixture values shown in Table 610.3 include both hot and cold water demand.

610.4 Sizing Water Supply and Distribution Systems. Systems within the range of Table 610.4 shall be permitted to be sized from that table or by the method in accordance with Section 610.5.

Listed parallel water distribution systems shall be installed in accordance with their listing, but at no time shall a portion of the system exceed the maximum velocities allowed by the code. 610.5 Sizing per Appendices A, C, and M . Except as provided in Section 610.4, the size of each water piping system shall be determined in accordance with the procedure set forth in Appendix A. For alternative methods of sizing water supply systems, see Appendix C or Appendix M . 610.6 Friction and Pressure Loss. Except where the type of pipe used and the water characteristics are such that no decrease in capacity due to the length of service (age of system) is expected, friction-loss data shall be obtained from the “Fairly Rough” or “Rough” charts in Appendix A of this code. Friction or pressure losses in a water meter, valve, and fittings shall be obtained from the same sources. Pressure losses through water-treating equipment, backflow prevention devices, or other flow-restricting devices shall be computed in accordance with Section 610.2. 610.7 Conditions for Using Table 610.4. On a proposed water piping installation sized using Table 610.4, the following conditions shall be determined:

(1) Total number of fixture units as determined from Table 610.3, Equivalent Fixture Units, for the fixtures to be installed.

(2) Developed length of supply pipe from meter to the most remote outlet.

(3) Difference in elevation between the meter or other source of supply and the highest fixture or outlet.

(4) Pressure in the street main or another source of supply at the locality where the installation is to be made.

(5) In localities where there is a fluctuation of pressure in the main throughout the day, the water piping system shall be designed on the basis of the minimum pressure available. 610.8 Size of Meter and Building Supply Pipe Using Table 610.4. The size of the meter and the building supply pipe shall be determined as follows:

(1) Determine the available pressure at the water meter or other source of supply.
CPC § 609.4 Medium relevance — show source text
609.4 Testing . . . . . . . . . . . . . . . . . . . . .155

609.5 Unions . . . . . . . . . . . . . . . . . . . . .155

609.6 Location . . . . . . . . . . . . . . . . . . . .155

609.7 Abutting Lot . . . . . . . . . . . . . . . . .155

609.8 Pumps . . . . . . . . . . . . . . . . . . . . .155

609.9 Low-Pressure Cutoff Required on Booster Pumps for Water Distribution Systems . . . . . . . . . . .156

2025 CALIFORNIA PLUMBING CODE xxxiii

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

TABLE OF CONTENTS

609.10 Disinfection of Potable Water System . . . . . . . . . . . . . . . . . . . . .156

609.11 Water Hammer . . . . . . . . . . . . . . .156

609.12 Pipe Insulation . . . . . . . . . . . . . . .156

610.0 Size of Potable Water Piping . . . .156

610.1 Size . . . . . . . . . . . . . . . . . . . . . . . .156

610.2 Pressure Loss . . . . . . . . . . . . . . . .156

610.3 Quantity of Water . . . . . . . . . . . . .157

610.4 Sizing Water Supply and Distribution Systems . . . . . . . . . . .157

610.5 Sizing per Appendices A, C, and M . . . . . . . . . . . . . . . . .157

610.6 Friction and Pressure Loss . . . . . .157

610.7 Conditions for Using Table 610.4 . . . . . . . . . . . . . . . . . .157

610.8 Size of Meter and Building Supply Pipe Using Table 610.4 . .157

610.9 Size of Branches . . . . . . . . . . . . .157

610.10 Sizing for Flushometer Valves . . .157

Table 610.10 Flushometer Fixture Units for Water Sizing Using Table 610.3 . . . . . . . . . . . . . . . . . .157

Table 610.3 Water Supply Fixture Units (WSFU) and Minimum Fixture Branch Pipe Sizes . . . . . . . . . . . .158

Table 610.4 Fixture Unit Table for

Determining Water Pipe and Meter Sizes . . . . . . . . . . . . . .159

610.11 Sizing Systems for Flushometer Tanks . . . . . . . . . . . .160

610.12 Sizing for Velocity . . . . . . . . . . . . .160

610.13 Exceptions . . . . . . . . . . . . . . . . . .160

611.0 Drinking Water Treatment Units . . . . . . . . . . . . . . . . . . . . . . .160

611.1 Application . . . . . . . . . . . . . . . . . .160
CPC § 1.11.0. Medium 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 365

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

366 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

APPENDIX A

RECOMMENDED RULES FOR SIZING THE WATER SUPPLY SYSTEM

The provisions contained in this appendix are not mandatory unless specifically adopted by a state agency, or referenced in the adopting ordinance.

A 101.0 General.

A 101.1 Applicability. This appendix provides a general procedure for sizing a water supply system. Because of the variable conditions encountered, it is impractical to lay down definite detailed rules of procedure for determining the sizes of water supply pipes in an appendix, which shall necessarily be limited in length. For an adequate understanding of the problems involved, refer to Water-Distributing Systems for Buildings, Report BMS 79 of the National Bureau of Standards; and Plumbing Manual, Report BMS 66, also published by the National Bureau of Standards.

A 102.0 Preliminary Information. A 102.1 Daily Service Pressure. Obtain the necessary information regarding the minimum daily service pressure in the area where the building is to be located. A 102.2 Water Meter. Where the building supply is to be metered, obtain information regarding friction loss relative to the rate of flow of meters in the range of sizes likely to be used. Friction-loss data is capable of being obtained from most manufacturers of water meters. Friction losses for disktype meters shall be permitted to be obtained from Chart A 102.2.

A 102.3 Local Information. Obtain available local information regarding the use of different kinds of pipe with respect both to durability and to decrease in capacity with the length of service in the particular water supply.

A 103.0 Demand Load.

A 103.1 Supply Demand. Estimate the supply demand for the building main, the principal branches and risers of the system by totaling the fixture units on each, Table A 103.1, and then by reading the corresponding ordinate from Chart A 103.1(1) or Chart A 103.1(2), whichever is applicable.

Exception: [HCD 1 & HCD 2] For the applicable fixtures, the supply demand flow rate values calculated using Appen- dix M may be substituted for the flow rates calculated using the fixture units in Table A 103.1 and Chart A 103.1(1) or Chart A 103.1(2), whichever is applicable.

A 103.2 Continuous Supply Demand. Estimate continuous supply demands in gallons per minute (gpm) (L/s) for lawn sprinklers, air conditioners, etc., and add the sum to the total demand for fixtures. The result is the estimated supply demand of the building supply.

A 104.0 Permissible Friction Loss.

A 104.1 Residual Pressure. Decide what is the desirable
CPC § 610.5 Medium relevance — show source text
610.5 Sizing per Appendices A, C, and M . . . . . . . . . . . . . . . . .157

610.6 Friction and Pressure Loss . . . . . .157

610.7 Conditions for Using Table 610.4 . . . . . . . . . . . . . . . . . .157

610.8 Size of Meter and Building Supply Pipe Using Table 610.4 . .157

610.9 Size of Branches . . . . . . . . . . . . .157

610.10 Sizing for Flushometer Valves . . .157

Table 610.10 Flushometer Fixture Units for Water Sizing Using Table 610.3 . . . . . . . . . . . . . . . . . .157

Table 610.3 Water Supply Fixture Units (WSFU) and Minimum Fixture Branch Pipe Sizes . . . . . . . . . . . .158

Table 610.4 Fixture Unit Table for

Determining Water Pipe and Meter Sizes . . . . . . . . . . . . . .159

610.11 Sizing Systems for Flushometer Tanks . . . . . . . . . . . .160

610.12 Sizing for Velocity . . . . . . . . . . . . .160

610.13 Exceptions . . . . . . . . . . . . . . . . . .160

611.0 Drinking Water Treatment Units . . . . . . . . . . . . . . . . . . . . . . .160

611.1 Application . . . . . . . . . . . . . . . . . .160

611.2 Air Gap Discharge . . . . . . . . . . . .160

611.3 Connection Tubing . . . . . . . . . . . .160

611.4 Sizing of Residential Softeners . . .160

612.0 Residential Fire Sprinkler Systems . . . . . . . . . . . . . . . . . . . .160

612.1 Installation . . . . . . . . . . . . . . . . . .160

Table 611.1 Drinking Water Treatment Units . . . . . . . . . . . . . . . . . . . . . . .161

Table 611.4 Sizing of Residential Water Softeners . . . . . . . . . . . . . . . . . . .161

613.0 Domestic Hot-Water Distribution Systems for Health Facilities and Clinics . . . . . . . . . . . . . . . . . .161

Table 613.1 Hot Water Use . . . . . . . . . . . . . . . . .161

614.0 Dialysis Water-Distribution Systems . . . . . . . . . . . . . . . . . . . . . .162

615.0 Identification of Potable and

Nonpotable Water Lines . . . . . . . . .162

615.1 Uses Not Permitted . . . . . . . . . . . . .162

616.0 Emergency Water Supply . . . . . . . .162

CHAPTER 7 SANITARY DRAINAGE . . . . . . . .163

PART I Drainage Systems . . . . . . . . . . .165
CPC § 609.12.3 Medium relevance — show source text
(2) Hot water piping between the fixture control valve or supply stop and the fixture or appliance shall not be required to be insulated. 609.12.3 California Energy Code Pipe Insulation Requirements. [CEC] See California Energy Code Sec- tions 150.0(j)2 and 120.3(c) for pipe insulation require- ments based on fluid temperature and pipe diameter – for domestic hot water piping. The California Energy Code requires that piping that penetrates metal framing shall use grommets, plugs, wrapping or other insulating mate- rial to assure that no contact is made with the metal fram- ing. The California Energy Code also requires that insulation shall abut securely against all framing mem- bers, and places conditions on when installed wall or attic insulation that surrounds installed piping can be consid- ered to provide pipe insulation meeting requirements.

610.0 Size of Potable Water Piping. 610.1 Size. The size of each water meter and each potable water supply pipe from the meter or other source of supply to the fixture supply branches, risers, fixtures, connections, outlets, or other uses shall be based on the total demand and shall be determined according to the methods and procedures outlined in this section. Water piping systems shall be designed to ensure that the maximum velocities allowed by the code and the applicable standard are not exceeded.

610.2 Pressure Loss. Where a water filter, water softener, backflow prevention device, tankless water heater, or similar device is installed in a water supply line, the pressure loss through such devices shall be included in the pressure loss calculations of the system, and the water supply pipe and meter shall be adequately sized to provide for such a pressure loss.

No water filter, water softener, backflow prevention device, or similar device regulated by this code shall be installed in a potable water supply piping where the installation of such device produces an excessive pressure drop in such water supply piping. In the absence of specific pressure drop information, the diameter of the inlet or outlet of such device or its connecting piping shall be not less than the diameter of such water distribution piping to the fixtures served by the device.

156 2025 CALIFORNIA PLUMBING CODE

), Copyright © 2025 IAPMO, and may not be used for any other purpose or distributed to any other persons or parties.

WATER SUPPLY AND DISTRIBUTION

Such devices shall be of a type approved by the Authority Having Jurisdiction and shall be tested for flow rating and pressure loss by an approved laboratory or recognized testing agency to standards consistent with the intent of this chapter. 610.3 Quantity of Water. The quantity of water required to be supplied to every plumbing fixture shall be represented by fixture units, as shown in Table 610.3. Equivalent fixture values shown in Table 610.3 include both hot and cold water demand.

610.4 Sizing Water Supply and Distribution Systems. Systems within the range of Table 610.4 shall be permitted to be sized from that table or by the method in accordance with Section 610.5.

Listed parallel water distribution systems shall be installed in accordance with their listing, but at no time shall a portion of the system exceed the maximum velocities allowed by the code. 610.5 Sizing per Appendices A, C, and M **.

CPC § 304.8 Medium relevance — show source text

r>NA
NA|NA
NA
NA
NA
NA|13
12
12
11
11|18
17
17
16
16|38
37
36
35
34|68
66
64
62
60|108
104
101
98
95|224
217
210
204
199|

For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm, 1 cubic foot per hour = 0.0283 m [3] /h, 1 pound-force per square inch = 6.8947 kPa, 1 inch water column = 0.249 kPa

Notes: 1 Table entries are rounded to 3 significant digits. 2 NA means a flow of less than 10 ft 3 /h (0.283 m 3 /h). 3 Table capacities are based on Type K copper tubing inside diameter (shown), which has the smallest inside diameter of the copper tubing products.

244 2025 CALIFORNIA PLUMBING CODE

FUEL GAS PIPING

TABLE 1215.2(9) SEMI-RIGID COPPER TUBING [NFPA 54: TABLE 6.2.1(j)]1, 2	Col2	Col3	Col4	Col5	Col6	Col7	Col8	Col9	Col10	Col11
							GAS:	GAS:	NATURAL	NATURAL
							INLET PRESSURE:	INLET PRESSURE:	LESS THAN 2 psi	LESS THAN 2 psi
							PRESSURE DROP:	PRESSURE DROP:	1.0 in. w.c.	1.0 in. w.c.
							SPECIFIC GRAVITY:	SPECIFIC GRAVITY:	0.60	0.60
INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE APPLIANCE	INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE APPLIANCE	INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE APPLIANCE	INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE APPLIANCE	INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE APPLIANCE	INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE APPLIANCE	INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE APPLIANCE	**INTENDED USE: TUBE SIZING BETWEEN HOUSE LINE REGULATOR AND THE

Sizing, Pressure and Flow Calculations

Overview

In this section

Code references

Frequently asked questions

More in California Plumbing Code

Ask about the CPC

Related in the CPC