Table 703.2
shows the maximum number of fixture units allowed on a
vertical or horizontal drainage pipe, building drain, or
building sewer of a given size; the maximum number of
fixture units allowed on a branch interval of a given size;
and the maximum length (in feet and meters) of a vertical
drainage pipe of a given size.
For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm
Notes:
1 Excluding trap arm.
2 Except sinks, urinals, and dishwashers - exceeding 1 fixture unit.
3 Except six-unit traps or water closets.
| SIZE OF PIPE (inches) | 11⁄4 | 11⁄2 | 2 | 3 | 4 | 5 | 6 | 8 | 10 | 12 |
| Maximum Units Drainage Piping1 Vertical Horizontal |
1 1 |
22 1 |
163 83 |
484 354 |
256 2165 |
600 4285 |
1380 7205 |
3600 26405 |
5600 46805 |
8400 82005 |
| Maximum Length Drainage Piping Vertical, (feet) Horizontal (unlimited) |
45 |
65 |
85 |
212 |
300 |
390 |
510 |
750 |
- | - |
| Vent Piping Horizontal and Vertical6 Maximum Units Maximum Lengths, (feet) |
1 45 |
83 60 |
24 120 |
84 212 |
256 300 |
600 390 |
1380 510 |
3600 750 |
- | - |
Notes:
1 Excluding trap arm.
2 Except sinks, urinals, and dishwashers - exceeding 1 fixture unit.
3 Except six-unit traps or water closets.
4 Only four water closets or six-unit traps allowed on a vertical pipe or stack; and not to exceed three water closets or six-unit traps on a horizontal branch
or drain.
5 Based on 1⁄4 inch per foot (20.8 mm/m) slope. For 1⁄8 of an inch per foot (10.4 mm/m) slope, multiply horizontal fixture units by a factor of 0.8.
6 The diameter of an individual vent shall be not less than 11⁄4 inches (32 mm) nor less than one-half the diameter of the drain to which it is connected.
Fixture unit load values for drainage and vent piping shall be computed from Table 702.1 and Table 702.2(2). Not to exceed one-third of the total
permitted length of a vent shall be permitted to be installed in a horizontal position. Where vents are increased one pipe size for their entire length, the
maximum length limitations specified in this table do not apply. This table is in accordance with the requirements of Section 901.3.