702.1 Trap Size — 2025 California Plumbing Code
California Plumbing Code (Title 24, Part 5) · 2025 edition · updated 2026-10-19 · California
CBSC: official editions, supplements and errata
Italicized text is a California amendment to the model code, as printed in the official publication.
Cite as: 2025 California Plumbing Code (Title 24, Part 5) § 702.1 · Effective January 1, 2026 · Official source: Building Standards Commission
The unit equivalent of plumbing fixtures shown in Table 702.1 shall be based on the size of the trap
TABLE 702.1 DRAINAGE FIXTURE UNIT VALUES (DFU)
| PLUMBING APPLIANCES, APPURTENANCES, OR FIXTURES | MINIMUM SIZE TRAP AND TRAP ARM7 (inches) |
PRIVATE | PUBLIC | ASSEMBLY8 |
|---|---|---|---|---|
| Bathtub or Combination Bath/ |
11⁄2 | 2.0 | 2.0 | –– |
| Bidet | 11⁄4 | 1.0 | –– | –– |
| Bidet | 11⁄2 | 2.0 | –– | –– |
| Clothes Washer, domestic, standpipe5 | 2 | 3.0 | 3.0 | 3.0 |
| Dental Unit, cuspidor | 11⁄4 | –– | 1.0 | 1.0 |
| Dishwasher, domestic, with independent drain2 | 11⁄2 | 2.0 | 2.0 | 2.0 |
| Drinking Fountain or Water Cooler | 11⁄4 | 0.5 | 0.5 | 1.0 |
| Food Waste Disposer, commercial | 2 | –– | 3.0 | 3.0 |
| Floor Drain, emergency | 2 | –– | 0.0 | 0.0 |
| Floor Drain (for additional sizes see Section 702.0) | 2 | 2.0 | 2.0 | 2.0 |
| Shower, single-head trap | 29 | 2.0 | 2.0 | 2.0 |
| Multi-head, each additional | 2 | 1.0 | 1.0 | 1.0 |
| Lavatory | 11⁄4 | 1.0 | 1.0 | 1.0 |
| Lavatories in sets | 11⁄2 | 2.0 | 2.0 | 2.0 |
| Washfountain | 11⁄2 | –– | 2.0 | 2.0 |
| Washfountain | 2 | –– | 3.0 | 3.0 |
| Mobilehome or Manufactured Home, trap_10_ | 3 | 6.0 | –– | –– |
| Receptor, indirect waste1,3 | 11⁄2 | See footnote1,3 | See footnote1,3 | See footnote1,3 |
| Receptor, indirect waste1,4 | 2 | See footnote1,4 | See footnote1,4 | See footnote1,4 |
| Receptor, indirect waste1 | 3 | See footnote1 | See footnote1 | See footnote1 |
| Sinks | –– | –– | –– | –– |
| Bar | 11⁄2 | 1.0 | –– | –– |
| Bar2 | 11⁄2 | –– | 2.0 | 2.0 |
| Clinical | 3 | –– | 6.0 | 6.0 |
| Commercial with food waste2 | 11⁄2 | –– | 3.0 | 3.0 |
| Exam Room | 11⁄2 | –– | 1.0 | –– |
| Special Purpose2 | 11⁄2 | 2.0 | 3.0 | 3.0 |
| Special Purpose | 2 | 3.0 | 4.0 | 4.0 |
| Special Purpose | 3 | –– | 6.0 | 6.0 |
| Kitchen, domestic2 (with or without food waste disposer, dishwasher, or both) |
11⁄2 | 2.0 | 2.0 | –– |
| Laundry2 (with or without discharge from a clothes washer) | 11⁄2 | 2.0 | 2.0 | 2.0 |
| Service or Mop Basin | 2 | –– | 3.0 | 3.0 |
| Service or Mop Basin | 3 | –– | 3.0 | 3.0 |
| Service, flushing rim | 3 | –– | 6.0 | 6.0 |
| Wash, each set of faucets | –– | –– | 2.0 | 2.0 |
| Nonwater Urinal with Drain Cleansing Action | 2 | 1.0 | 1.0 | 1.0 |
| Urinal, integral trap 1.0 GPF2 | 2 | 2.0 | 2.0 | 5.0 |
| Urinal, integral trap greater than 1.0 GPF | 2 | 2.0 | 2.0 | 6.0 |
| Urinal, exposed trap2 | 11⁄2 | 2.0 | 2.0 | 5.0 |
| Water Closet, 1.6 GPF Gravity Tank6 | 3 | 3.0 | 4.0 | 6.0 |
| Water Closet, 1.6 GPF Flushometer Tank6 | 3 | 3.0 | 4.0 | 6.0 |
| Water Closet, 1.6 GPF Flushometer Valve6 | 3 | 3.0 | 4.0 | 6.0 |
TABLE 702.1 DRAINAGE FIXTURE UNIT VALUES (DFU) (continued)
| PLUMBING APPLIANCES, APPURTENANCES, OR FIXTURES | MINIMUM SIZE TRAP AND TRAP ARM7 (inches) |
PRIVATE | PUBLIC | ASSEMBLY8 |
|---|---|---|---|---|
| Water Closet, greater than 1.6 GPF Gravity Tank6 | 3 | 4.0 | 6.0 | 8.0 |
| Water Closet, greater than 1.6 GPF Flushometer Valve6 | 3 | 4.0 | 6.0 | 8.0 |
For SI units: 1 inch = 25 mm
Notes: 1 Indirect waste receptors shall be sized based on the total drainage capacity of the fixtures that drain thereinto, in accordance with Table 702.2. 2 Provide a 2 inch (50 mm) minimum drain. 3 For refrigerators, coffee urns, water stations, and similar low demands. 4 For commercial sinks, dishwashers, and similar moderate or heavy demands. 5 Buildings having a clothes-washing area with clothes washers in a battery of three or more clothes washers shall be rated at 6 fixture units each for purposes of sizing common horizontal and vertical drainage piping. 6 Water closets shall be computed as 6 fixture units where determining septic tank sizes based on Appendix H of this code. 7 Trap sizes shall not be increased to the point where the fixture discharge is capable of being inadequate to maintain their self-scouring properties. 8 Assembly [Public Use (see Table 422.1)]. 9 For a bathtub to shower retrofit, a 1 1 / 2 inch (40 mm) trap and trap arm shall be permitted with a maximum shower size of 36 inches (914 mm) in width and 60 inches (1524 mm) in length. See Section 408.6 and Section 408.7. 10 For drainage 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 1268. For drainage fixture unit values related to lots within special occupancy parks in all parts of the State of Cal- ifornia, see California Code of Regulations, Title 25, Division 1, Chapter 2.2, Article 5, Section 2268.
required, and the unit equivalent of fixtures and devices not shown in Table 702.1 shall be based on the size of trap or trap
arm.
Maximum drainage fixture units for a fixture trap and trap arm loadings for sizes up to 4 inches (100 mm) shall be in accordance with Table 702.1(1).
TABLE 702.1(1) MAXIMUM DRAINAGE FIXTURE UNITS FOR A
TRAP AND TRAP ARM*
| SIZE OF TRAP AND TRAP ARM (inches) |
DRAINAGE FIXTURE UNIT VALUES (DFU) |
|---|---|
11⁄4 |
1 unit |
11⁄2 |
3 units |
2 |
4 units |
| 3 | 6 units |
4 |
8 units |
For SI Units: 1 inch = 25 mm
*** Exception:** On self-service laundries.
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