1. A. Maximum Fixture Unit Load. The maximum number of fixture units that may be connected to a given size of building sewer, building drain, or horizontal branch of the building drain shall be determined using Table 725.A.1 of this code below. The maximum number of fixture units that may be connected to a given size vertical soil or waste stack, or a horizontal branch connecting to a vertical soil or waste stack, is given in Table 725.A.2 of this code.

   Table 725.A.1 Building Drains and Sewers
   Maximum Number of Fixture-Units that may be Connected to Any Portion of the Building Drain or the Building Sewer (Includes branches of the building drain. The minimum size of any building drain serving a water closet shall be 3". No building sewer shall be less than 4 inches in size)
   Diameter of Pipe (in.)	Fall in Inches Per Foot
   	1/16	1/8	1/4	1/2
   2	-	-	21	26
   3	-	20 (not over two water closets)	27 (not over two water closets)	36 (not over two water closets)
   4	-	180	216	250
   5	-	390	480	575
   6	-	700	840	1,000
   8	1,400	1,600	1,920	2,300
   10	2,500	2,900	3,500	4,200
   12	3,900	4,600	5,600	6,700
   15	7,000	8,300	10,000	2,000

   Table 725.A.2 Horizontal Fixture Branches and Stacks
   Diameter of Pipe (in.) (The minimum size of any branch or stack serving a water closet shall be 3")	Any Horizontal Fixture Branch (Does not include branches of the building drain. 50 percent less for battery vented fixture branches, no size reduction permitted for battery vented branches throughout the entire branch length.)	Maximum Number of Fixture Units that May be Connected to:
   		One Stack of 3 Stories or 3 Intervals Maximum	More Than 3 Stories in Height
   			Total for Stack	Total at One Story or Branch Interval
   1 1/4	1	2	2	1
   1 1/2	3	4	8	2
   2	6	10	24	6
   3	20 (not over two water closets)	30 (not over six water closets)	60 (not over six water closets)	16 (not over two water closets)
   4	160	240	500	90
   5	360	540	1100	200
   6	620	960	1900	350
   8	1400	2200	3600	600
   10	2500	3800	5600	1000
   12	3900	6000	8400	1500
   15	7000	---	---	---

2. B. Minimum Size of Soil and Waste Stacks. No soil or waste stack shall be smaller than the largest horizontal branch connected thereto except that a 4x3 water closet connection shall not be considered as a reduction in pipe size. The soil or waste stack shall run undiminished in size from its connection to the building drain to its connection to the stack vent.
3. C. Future Fixtures. When provision is made for the future installation of fixtures, those provided for shall be considered in determining the required sizes of drain pipes. Construction to provide for such future installation shall be terminated with a plugged fitting or fittings at the stack so as to form no dead end.
4. D. Underground Drainage Piping. Any portion of the drainage system installed underground or below a basement or cellar shall not be less than 2-inch diameter. In addition, any portion of the drainage system installed underground which is located upstream from a grease trap or grease interceptor as well as the underground horizontal branch receiving the discharge there from shall not be less than 3-inch diameter.

Authority Note

AUTHORITY NOTE: Promulgated in accordance with R.S. 40:4(A)(7) and R.S. 40:5(2)(3)(7)(9)(16)(17)(20).

Historical Note

HISTORICAL NOTE: Promulgated by the Department of Health and Hospitals, Office of Public Health, LR 38:2854 (November 2012).