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Chapter 6 — WATER SUPPLY AND DISTRIBUTION

610.6 Friction and Pressure Loss.

California Plumbing Code (Title 24, Part 5) · 2022 edition · updated 2026-09-12 · California

CBSC: official editions, supplements and errata

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

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.

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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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