Chapter 10 — TRAPS AND INTERCEPTORS
1002.2 Fixture Traps — 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) § 1002.2 · Effective January 1, 2026 · Official source: Building Standards Commission
Each fixture trap shall have a protecting vent so located that the developed length of the trap arm from the trap weir to the inner edge of the vent shall be within the distance given in Table 1002.2 but in no case less than two times the diameter of the trap arm. TABLE 1002.2
HORIZONTAL LENGTHS OF TRAP ARMS (EXCEPT FOR WATER CLOSETS AND SIMILAR FIXTURES) [1, 2, 3]
| TRAP ARM PIPE DIAMETER (inches) |
DISTANCE TRAP TO VENT MINIMUM (inches) |
LENGTH MAXIMUM (inches) |
|---|---|---|
| 11⁄4 | 21⁄2 | 30 |
11⁄2 |
3 | 42 |
2 |
4 | 60 |
3 |
6 | 72 |
4 |
8 | 120 |
Exceeding 4 |
2 x Diameter | 120 |
For SI units: 1 inch = 25.4 mm
Notes: 1 Maintain 1 ⁄ 4 inch per foot slope (20.8 mm/m). 2 The developed length between the trap of a water closet or similar fixture (measured from the face of the closet flange to the inner edge of the vent) and its vent shall not exceed 6 feet (1829 mm). 3 Horizontally wet vented bathtubs, showers and similar fixtures shall be limited to a maximum of 6 feet (1829 mm) for 1½ inch (40 mm) fixture drains and 8 feet (2438 mm) for 2 inch (50 mm) fixture drains, maintaining ¼ inch per foot slope (20.8 mm/m).
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