N.Y.C. Admin. Code § PC 710: Section PC 710: Drainage System Sizing

710.1 Maximum fixture unit load.

The maximum number of drainage fixture units connected to a given size of building sewer, building drain or horizontal branch of the building drain shall be determined using Table 710.1(1). The maximum number of drainage fixture units connected to a given size of horizontal branch or vertical soil or waste stack shall be determined using Table 710.1(2).

Table 710.1(1) Building Drains and Sewers

Diameter of Pipe (inches)

Maximum Number of Drainage Fixture Units Connected to any Portion of the Building Drain or the Building Sewer, Including Branches of the Building Drain

a

Slope per foot

1/16 inch

1/8 inch

1/4 inch

1/2 inch

1 1/4

—

—

1

1

1 1/2

—

—

3

3

2

—

—

21

26

2 1/2

—

—

24

31

3

—

36

42

50

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

12,000

For SI: 1 inch = 25.4 mm, 1 inch per foot = 83.3 mm/m.

a. The minimum size of any building drain serving a water closet shall be 3 inches.

Table 710.1(2) Horizontal Fixture Branches and Stacks

a

Diameter of Pipe (inches)

Total for horizontal branch

Maximum Number of Drainage Fixture Units (dfu)

Stacks

b

Total for Stack of Three Branch Intervals or Less

Total for Stack Greater than Three Branch Intervals

1 1/2

3

4

8

2

6

10

24

2 1/2

12

20

42

3

20

48

72

4

160

240

500

5

360

540

1,100

6

620

960

1,900

8

1,400

2,200

3,600

10

2,500

3,800

5,600

12

2,900

6,000

8,400

15

7,000

Note c

Note c

For SI:1 inch = 25.4 mm

a. Does not include branches of the building drain. Refer to Table 710.1(1).

b. Stacks shall be sized based on the total accumulated connected load at each story or branch interval. No soil or waste stack shall be smaller than any horizontal branch connection thereto.

c. Sizing load based on design criteria.

710.1.1 Horizontal stack offsets.

Horizontal stack offsets shall be sized as required for building drains in accordance with

Table 710.1(1)

, except as required by Section 711.3.

710.1.2 Vertical stack offsets.

Vertical stack offsets shall be sized as required for straight stacks in accordance with

Table 710.1(2)

, except where required to be sized as a building drain in accordance with Section 711.1.1.

710.2 Future fixtures.

Where provision is made for the future installation of fixtures, those provided for shall be considered in determining the required sizes of drain pipes.