Sec. 24. Size of Horizontal and Vertical Waste Pipes, Traps and Branches.—

Horizontal and verticalNumber of small fixtures
11⁄4-inch..............................1
11⁄2-inch..............................2
2 -inch..............................3 to 8
21⁄2-inch..............................9 to 20
3 -inch..............................21 to 44

If building is ten (10) or more stories in height, the vertical waste pipe shall not be less than 3 inches in diameter. The use of wrought-iron pipe for waste pipe 2 inches or less in diameter is prohibited.

The size of traps and waste branches, for a given fixture, shall be as follows:

Kind of fixturesSize in inches
TrapBranch
Water closet...................................................34
Slop sink with trap combined..........................33
Slop sink ordinary...........................................22
Pedestal urinal................................................33
Floor drain or wash.........................................44
Yard drain or catch basin................................44
Urinal trough...................................................22
Laundry trays, two or five................................22
Combination sink and tray (for each fixture).....11⁄2 2
Kitchen sinks, small.........................................11⁄211⁄2
Kitchen sinks, large hotel, etc..........................
Kitchen sinks, grease trap...............................2
Pantry sinks....................................................11⁄211⁄2
Wash basin, one only......................................11⁄411⁄4
Bath tub..........................................................22
Shower baths..................................................11⁄211⁄2
Shower baths, floor.........................................22
Sitz bath..........................................................11⁄211⁄2
Drinking fountains............................................11⁄411⁄4

Sec. 25. Overflow Pipes.—Overflow pipes from fixtures must in all cases be connected on the inlet side of the traps.

Sec. 26. Setting of Traps Without Re-vent.—All traps must be substantially supported and set true with respect to their water levels. No pot, bottle or "D" trap will be permitted nor any form of trap that is not self-cleaning, nor that has interior chambers or mechanism nor any trap except earthenware ones that depend upon interior partitions for a seal. In case there is an additional fixture required in building and it is impossible to re-vent pipe for the trap, the building department may designate the kind of trap to be used. This shall not be construed to allow traps without re-vents in new buildings.

Sec. 27. Safe and Refrigerator Pipes.—Safe-waste pipes must not connect directly with any part of the plumbing system. Safe-waste pipes must discharge over an open, water-supplied, publicly-placed, ordinary-used sink, placed not more than 31⁄2 feet above the cellar floor. The safe waste from a refrigerator must be trapped at the bottom of the line only and must not discharge upon the ground floor, but over an ordinary open pan, or some properly-trapped, water-supplied sink, as above. In no case shall the refrigerator waste pipe discharge into a sink located in a living room.

The branches on vertical lines must be made by means of "Y" fittings and be carried to the safe with as much pitch as possible. Where there is an offset on the refrigerator waste pipe in the cellar, there must be clean-outs placed. These clean-outs must be of brass.

In tenement and lodging houses the refrigerator waste pipe must extend above the roof, and not be larger than 11⁄2 inches and the branches not smaller than 11⁄4 inches. Refrigerator waste pipes, except in tenement houses, and all safe-waste pipes, must have brass flap valve on the lower ends. Lead safes must be graded and neatly turned over beveled strips at their edges.