The Chicago Plumbing Code

Table § 18-29-604.5

Minimum Sizes of Fixture Water Supply Pipes

Fixture

Minimum Pipe Size (inch)

Bathtubs: 60" by 32" and smaller

1/2

Bathtubs: Larger than 60" by 32"

1/2

Bidet

3/8

Combination sink and tray

1/2

Dishwashing machine (domestic)

1/2

Drinking fountain

1/2

Hose bibbs

3/4

Kitchen sink

1/2

Domestic

3/4

Commercial

3/4

Laundry, 1, 2 or 3 compartments

1/2

Lavatory

3/8

Shower, single head

1/2

Sinks, flushing rim

3/4

Sinks, service

3/4

Urinal, flush tank

1/2

Urinal, flush valve

1

Wall hydrant

3/4

Washing machine (automatic)

1/2

Water closet, flush tank

1/2

Water closet, flush valve

1

Water closet, flushometer tank

3/8

Water closet, one piece

1/2

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 psi = 6.895 kPa.