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/ |
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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