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Chapter 6 — WATER SUPPLY AND DISTRIBUTION

610.6 Friction and Pressure Loss. Except where the type

California Plumbing Code (Title 24, Part 5) · 2022 edition · updated 2026-09-10 · California

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

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.

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TABLE 610.3 WATER SUPPLY FIXTURE UNITS (WSFU) AND MINIMUM FIXTURE BRANCH PIPE SIZES 3

APPLIANCES, APPURTENANCES OR FIXTURES2 MINIMUM FIXTURE
BRANCH PIPE SIZE1,4
(inches)		 PRIVATE PUBLIC ASSEMBLY6
Bathtub or Combination Bath/Shower (fill) 1⁄2 4.0 4.0 ––
3⁄4 inch Bathtub Fill Valve 3⁄4 10.0 10.0 ––
Bidet 1⁄2 1.0 –– ––
Clothes Washer 1⁄2 4.0 4.0 ––
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 additional8 1⁄2 1.0 1.0 ––
Lavatory 1⁄2 1.0 1.0 1.0
Lawn Sprinkler, each head5 –– 1.0 1.0 ––
Mobilehome or Manufactured Home, each (minimum) –– 6.0 –– ––
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 See Footnote7 See Footnote7 ––
Urinal, greater than 1.0 GPF Flushometer Valve 3⁄4 See Footnote7 See Footnote7 ––
Urinal, flush tank 1⁄2 2.0 2.0 3.0
Urinal with Drain Cleansing Action 1⁄2 1.0 1.0 1.0
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 See Footnote7 See Footnote7 ––
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 See Footnote7 See Footnote7 ––

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 referenced 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 load on the cold water building supply. The separate cold water and hot water fixture unit value for fixtures having both hot and cold water connections shall be permitted to be each taken as three-quarter 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. 5 For fixtures or supply connections likely to impose continuous flow demands, determine the required flow in gallons per minute (gpm) (L/s), and add it separately to the demand in gpm (L/s) for the distribution system or portions thereof. 6 Assembly [Public Use (See Table 422.1)]. 7 Where sizing flushometer systems, see Section 610.10. 8 Reduced fixture unit loading for additional hose bibbs is to be used where sizing total building demand and for pipe sizing where more than one hose bibb is supplied by a segment of water distribution pipe. The fixture branch to each hose bibb shall be sized on the basis of 2.5 fixture units. 9 For water supply fixture unit values related to lots within mobilehome parks in all parts of the State of California, see California Code of Regulations, Title 25, Division 1, Chapter 2, Article 5, Section 1278. For water supply fixture unit values related to lots within special occupancy parks in all parts of the State of California, see California Code of Regulations, Title 25, Division 1, Chapter 2.2, Article 5, Section 2278.

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TABLE 610.4 FIXTURE UNIT TABLE FOR DETERMINING WATER PIPE AND METER SIZES
METER AND
STREET
SERVICE
(inches)		 BUILDING
SUPPLY
AND
BRANCHES
(inches)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)		 MAXIMUM ALLOWABLE LENGTH
(feet)
METER AND
STREET
SERVICE
(inches)		 BUILDING
SUPPLY
AND
BRANCHES
(inches)		 40 60 80 100 150 200 250 300 400 500 600 700 800 900 1000
PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1 PRESSURE RANGE – 30 to 45 psi1
3⁄4
 1⁄22
 6 5 4 3 2 1 1 1 0 0 0 0 0 0 0
3⁄4
 3⁄4 16 16 14 12 9 6 5 5 4 4 3 2 2 2 1
3⁄4 1 29 25 23 21 17 15 13 12 10 8 6 6 6 6 6
1
 1
 36 31 27 25 20 17 15 13 12 10 8 6 6 6 6
3⁄4 11⁄4
 36 33 31 28 24 23 21 19 17 16 13 12 12 11 11
1
 11⁄4
 54 47 42 38 32 28 25 23 19 17 14 12 12 11 11
11⁄2 11⁄4
 78 68 57 48 38 32 28 25 21 18 15 12 12 11 11
1
 11⁄2
 85 84 79 65 56 48 43 38 32 28 26 22 21 20 20
11⁄2 11⁄2
 150 124 105 91 70 57 49 45 36 31 26 23 21 20 20
2 11⁄2 151 129 129 110 80 64 53 46 38 32 27 23 21 20 20
1
 2 85 85 85 85 85 85 82 80 66 61 57 52 49 46 43
11⁄2 2 220 205 190 176 155 138 127 120 104 85 70 61 57 54 51
2 2
 370 327 292 265 217 185 164 147 124 96 70 61 57 54 51
2 21⁄2 445 418 390 370 330 300 280 265 240 220 198 175 158 143 133
PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1 PRESSURE RANGE – 46 to 60 psi1
3⁄4
 1⁄22
 7 7 6 5 4 3 2 2 1 1 1 0 0 0 0
3⁄4
 3⁄4 20 20 19 17 14 11 9 8 6 5 4 4 3 3 3
3⁄4 1 39 39 36 33 28 23 21 19 17 14 12 10 9 8 8
1
 1
 39 39 39 36 30 25 23 20 18 15 12 10 9 8 8
3⁄4 11⁄4
 39 39 39 39 39 39 34 32 27 25 22 19 19 17 16
1
 11⁄4
 78 78 76 67 52 44 39 36 30 27 24 20 19 17 16
11⁄2 11⁄4
 78 78 78 78 66 52 44 39 33 29 24 20 19 17 16
1
 11⁄2
 85 85 85 85 85 85 80 67 55 49 41 37 34 32 30
11⁄2 11⁄2
 151 151 151 151 128 105 90 78 62 52 42 38 35 32 30
2 11⁄2 151 151 151 151 150 117 98 84 67 55 42 38 35 32 30
1
 2 85 85 85 85 85 85 85 85 85 85 85 85 85 83 80
11⁄2 2 370 370 340 318 272 240 220 198 170 150 135 123 110 102 94
2 2
 370 370 370 370 368 318 280 250 205 165 142 123 110 102 94
2 21⁄2 654 640 610 580 535 500 470 440 400 365 335 315 285 267 250
PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1 PRESSURE RANGE – Over 60 psi1
3⁄4
 1⁄22
 7 7 7 6 5 4 3 3 2 1 1 1 1 1 0
3⁄4
 3⁄4 20 20 20 20 17 13 11 10 8 7 6 6 5 4 4
3⁄4 1 39 39 39 39 35 30 27 24 21 17 14 13 12 12 11
1
 1
 39 39 39 39 38 32 29 26 22 18 14 13 12 12 11
3⁄4 11⁄4
 39 39 39 39 39 39 39 39 34 28 26 25 23 22 21
1
 11⁄4
 78 78 78 78 74 62 53 47 39 31 26 25 23 22 21
11⁄2 11⁄4
 78 78 78 78 78 74 65 54 43 34 26 25 23 22 21
1
 11⁄2
 85 85 85 85 85 85 85 85 81 64 51 48 46 43 40
11⁄2 11⁄2
 151 151 151 151 151 151 130 113 88 73 51 51 46 43 40
2 11⁄2 151 151 151 151 151 151 142 122 98 82 64 51 46 43 40
1
 2 85 85 85 85 85 85 85 85 85 85 85 85 85 85 85
11⁄2 2 370 370 370 370 360 335 305 282 244 212 187 172 153 141 129
2 2
 370 370 370 370 370 370 370 340 288 245 204 172 153 141 129
2 21⁄2 654 654 654 654 654 650 610 570 510 460 430 404 380 356 329

For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm, 1 pound-force per square inch = 6.8947 kPa Notes: 1 Available static pressure after head loss. 2 Building supply, not less than 3 ⁄ 4 of an inch (20 mm) nominal size.

158 2022 CALIFORNIA PLUMBING CODE

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▸Contents — California Plumbing Code (Title 24, Part 5)
California Plumbing Code (Title 24, Part 5)
  1. Chapter 1 — GENERAL CODE PROVISIONS
  2. Chapter 2 — DEFINITIONS
  3. Chapter 3 — GENERAL REGULATIONS
  4. Chapter 4 — PLUMBING FIXTURES AND FIXTURE FITTINGS
  5. Chapter 5 — WATER HEATERS
  6. ▸Chapter 6 — WATER SUPPLY AND DISTRIBUTION
    Overview
    1. 601.1 Applicability. This chapter shall govern the materials,
    2. 601.2 Water Supply and Flushing. Each plumbing fixture shall b…
    3. 601.3 Identification of a Potable and Nonpotable
    4. 601.4 [CA] Schools of Cosmetology and Cosmeto-
    5. 601.5 [AGR] Meat and Poultry Processing Plants.
    6. 601.6 [AGR] Collection Centers and Facilities.
    7. 601.7 [AGR] Renderers. This area shall be provided with
    8. 601.8 [AGR] Horse Meat and Pet Food Establishments.
    9. 602.1 Prohibited Installation. No installation of potable
    10. 602.2 Cross-Contamination. No person shall make a connection o…
    11. 602.3 Backflow Prevention. No plumbing fixture, device,
    12. 602.4 Approval by Authority. No water piping supplied
    13. 603.1 General. Cross-connection control shall be provided
    14. 603.2 Approval of Devices or Assemblies. Before a
    15. 603.3 Backflow Prevention Devices, Assemblies, and
    16. 603.4 General Requirements. Assemblies shall comply
    17. 603.5 Specific Requirements. Specific requirements for
    18. 604.1 Pipe, Tube, and Fittings. Pipe, tube, fittings, solvent …
    19. 604.2 Lead Content. The maximum allowable lead content in pipe…
    20. 604.3 Copper or Copper Alloy Tube. Copper or copper
    21. 604.4 Hard-Drawn Copper or Copper Alloy Tubing.
    22. 604.5 Flexible Connectors. Flexible water connectors
    23. 604.6 Cast-Iron Fittings. Cast-iron fittings up to and
    24. 604.7 Malleable Iron Fittings. Malleable iron water fittings s…
    25. 604.8 Previously Used Piping and Tubing. Piping and
    26. 604.9 Epoxy Coating. The epoxy coating used on existing, under…
    27. 604.10 Plastic Materials. Approved plastic materials shall
    28. 604.11 Solder. Solder shall comply with the requirements of
    29. 604.12 Flexible Corrugated Connectors. Flexible corrugated con…
    30. 604.13 Water Heater Connectors. Flexible metallic (copper and …
    31. 605.1 Copper or Copper Alloy Pipe, Tubing, and
    32. 605.2 CPVC Plastic Pipe and Joints. CPVC plastic pipe
    33. 605.3 CPVC/AL/CPVC Plastic Pipe and Joints. Chlorinated polyvi…
    34. 605.4 Ductile Iron Pipe and Joints. Ductile iron pipe
    35. 605.5 Galvanized Steel Pipe and Joints. Galvanized
    36. 605.6 PE Plastic Pipe/Tubing and Joints. PE plastic
    37. 605.7 PE-AL-PE Plastic Pipe/Tubing and Joints. PEAL-PE plastic…
    38. 605.8 PE-RT. Polyethylene of raised temperature (PE-RT)
    39. 605.9 PEX Plastic Tubing and Joints. PEX plastic tubing and fi…
    40. 605.10 PEX-AL-PEX Plastic Tubing and Joints. PEXAL-PEX plastic…
    41. 605.11 Polypropylene (PP) Piping and Joints. PP pipe
    42. 605.12 PVC Plastic Pipe and Joints. PVC plastic pipe
    43. 605.13 Stainless Steel Pipe and Joints. Joining methods for st…
    44. 605.14 Slip Joints. In water piping, slip joints shall be perm…
    45. 605.15 Dielectric Unions. Dielectric unions where
    46. 605.16 Joints Between Various Materials. Joints
    47. 606.1 General. Valves up to and including 2 inches (50
    48. 606.2 Fullway Valve. A fullway valve controlling outlets
    49. 606.3 Multidwelling Units. In multidwelling units, one or
    50. 606.4 Multiple Openings. Valves used to control two or
    51. 606.5 Control Valve. A control valve shall be installed
    52. 606.6 Accessible. Required shutoff or control valves shall
    53. 606.7 Multiple Fixtures. A single control valve shall be
    54. 606.8 [OSHPD 1, 1R, 2, 3, 4 & 5] Each riser or branch
    55. 606.9 Check Valve Required. All systems that circulate
    56. 606.10 Leak Detection Devices. Where leak detection
    57. 607.1 General. Potable water supply tanks shall be installed
    58. 607.2 Potable Water Tanks. Potable water supply tanks,
    59. 607.3 Venting. Tanks used for potable water shall be tightly
    60. 607.4 Overflow. Tanks shall have not less than a 16 square
    61. 607.5 Valves. Pressurized tanks shall be provided with a
    62. 608.1 Inadequate Water Pressure. Where the water pressure in t…
    63. 608.2 Excessive Water Pressure. Where static water
    64. 608.3 Expansion Tanks, and Combination Tempera-
    65. 608.4 Pressure Relief Valves. Each pressure relief valve
    66. 608.5 Discharge Piping. The discharge piping serving a
    67. 608.6 Water-Heating Devices. A water-heating device
    68. 608.7 Vacuum Relief Valves. Where a hot-water storage
    69. 609.1 Installation. Water piping shall be adequately supported…
    70. 609.2 Trenches. Water pipes shall not be run or laid in the
    71. 609.3 Under Concrete Slab. Water piping installed within
    72. 609.4 Testing. Upon completion of a section or of the entire
    73. 609.5 Unions. Unions shall be installed in the water supply
    74. 609.6 Location. Except as provided in Section 609.7, no
    75. 609.7 Abutting Lot. Nothing contained in this code shall
    76. 609.8 Pumps. Pumps shall be installed in accordance with
    77. 609.9 Low-Pressure Cutoff Required on Booster
    78. 609.10 Disinfection of Potable Water System. New or
    79. 609.11 Water Hammer. [Not adopted by HCD] Building
    80. 609.12 Pipe Insulation. Insulation of domestic hot water
    81. 610.1 Size. The size of each water meter and each potable
    82. 610.2 Pressure Loss. Where a water filter, water softener,
    83. 610.3 Quantity of Water. The quantity of water required to
    84. 610.4 Sizing Water Supply and Distribution Systems.
    85. 610.5 Sizing per Appendices A and C. Except as provided in Sec…
    86. 610.6 Friction and Pressure Loss. Except where the type
    87. 610.7 Conditions for Using Table 610.4. On a proposed
    88. 610.8 Size of Meter and Building Supply Pipe Using
    89. 610.9 Size of Branches. Where Table 610.4 is used, the
    90. 610.10 Sizing for Flushometer Valves. Where using
    91. 610.11 Sizing Systems for Flushometer Tanks. The size
    92. 610.12 Sizing for Velocity. Water piping systems shall not
    93. 610.13 Exceptions. The provisions of this section relative
    94. 611.1 Application. Drinking water treatment units shall
    95. 611.2 Air Gap Discharge. Discharge from drinking water
    96. 611.3 Connection Tubing. The tubing to and from drinking water…
    97. 611.4 Sizing of Residential Softeners. Residential-use
    98. 612.1 Installation. Residential Sprinkler Systems shall be
    99. 613.1 The domestic water-heating equipment and distribu-
    100. 613.2 At least two pieces of hot-water-heating equipment shall
    101. 613.3 Instantaneous heaters are permitted for supplying hot
    102. 613.4 Water storage tanks shall be fabricated of corrosion-
    103. 613.5 Temperature control valves shall be provided to auto-
    104. 613.6 Hot-water distribution system serving patient care
    105. 613.7 At fixtures where water exceeding 125°F (52°C) is acces-
    106. 613.8 Sectionalizing valves shall be provided as required by
    107. 614.1 [OSHPD 1, 1R, 2, 3, 4 & 5] Dialysis water feedlines
    108. 614.2 All piping for multistation or central dialysis units sh…
    109. 614.3 All valves shall be located in accessible locations.
    110. 614.4 Piping and valves shall be identified according to their
    111. 614.5 A means of preventing backwashing or flushing of the
    112. 614.6 A continuous audible alarm shall sound at the nurses’
    113. 614.7 Water used for dialysis treatment shall meet the latest
    114. 614.8 A diagram of all piping as installed shall be posted at …
    115. 615.1 Uses Not Permitted.
    116. 615.2 [OSHPD 1, 1R, 2, 3, 4 & 5] Non-potable water sys-
    117. 615.3 [OSHPD 1, 1R, 2, 3, 4 & 5] Outlets for non-potable
    118. 615.4 [OSHPD 1] Emergency Water Supply.
  7. Chapter 7 — SANITARY DRAINAGE
  8. Chapter 8 — INDIRECT WASTES
  9. Chapter 9 — VENTS
  10. Chapter 10 — TRAPS AND INTERCEPTORS
  11. Chapter 11 — STORM DRAINAGE
  12. Chapter 12 — FUEL GAS PIPING
  13. Chapter 13 — HEALTH CARE FACILITIES AND MEDICAL GAS AND MEDICA…
  14. Chapter 14 — FIRESTOP PROTECTION
  15. Chapter 15 — ALTERNATE WATER SOURCES FOR NONPOTABLE APPLICATIONS
  16. Chapter 16 — NONPOTABLE RAINWATER CATCHMENT SYSTEMS
  17. Chapter 17 — REFERENCED STANDARDS
  18. Appendix A — RECOMMENDED RULES FOR SIZING THE WATER SUPPLY SYS…
  19. Appendix B — EXPLANATORY NOTES ON COMBINATION WASTE AND VENT S…
  20. Appendix C — ALTERNATE PLUMBING SYSTEMS
  21. Appendix D — SIZING STORM WATER DRAINAGE SYSTEMS
  22. Appendix E — MANUFACTURED/MOBILE HOME PARKS AND RECREATIONAL V…
  23. Appendix F — FIREFIGHTER BREATHING AIR REPLENISHMENT SYSTEMS
  24. Appendix G — SIZING OF VENTING SYSTEMS
  25. Appendix H — PRIVATE SEWAGE DISPOSAL SYSTEMS
  26. Appendix I — INSTALLATION STANDARDS
  27. Appendix J — COMBINATION OF INDOOR AND OUTDOOR COMBUSTION AND …
  28. Appendix K — POTABLE RAINWATER CATCHMENT SYSTEMS
  29. Appendix L — SUSTAINABLE PRACTICES
  30. Appendix M — PEAK WATER DEMAND CALCULATOR
  31. Appendix N — IMPACT OF WATER TEMPERATURE ON THE POTENTIAL FOR …

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