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703.2 Maximum Number of Fixture Units

California Plumbing Code 2019 > 7 Sanitary Drainage > 703.0 Size of Drainage Piping > 703.2 Maximum Number of Fixture Units

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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.

TABLE 703.2
MAXIMUM UNIT LOADING AND MAXIMUM LENGTH OF DRAINAGE AND VENT PIPING
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	-	-

For SI units: 1 inch = 25 mm, 1 foot = 304.8 mm
Notes:

¹ Excluding trap arm.
² Except for sinks, urinals, and dishwashers - exceeding 1 fixture unit.
³ Except for 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.