18-29-604.5 Size of fixture supply.

   The minimum size of a fixture supply pipe shall be as shown in Table 18-29-604.5. The fixture supply pipe shall not terminate more than 30 inches (762 mm) from the point of connection to the fixture. A reduced-size connector installed between the supply pipe and the fixture shall be of approved type. The supply pipe shall extend to the floor or wall adjacent to the fixture.

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	3/8
Hose bibbs	1/2
Kitchen sink	1/2
Laundry, 1, 2 or 3 compartments	1/2
Lavatory	3/8
Shower, single head	1/2
Sinks, flushing rim	3/4
Sinks, service	1/2
Urinal, flush tank	1/2
Urinal, flushometer valve	3/4
Wall hydrant	1/2
Washing machine (automatic)	1/2
Water closet, flush tank	3/8
Water closet, flushometer 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.

(Amend Coun. J. 10-14-21, p. 37722, Art. VI, § 10)

18-29-604.5.1 Minimum size.

   The minimum size of individual distribution lines utilized in parallel water distribution systems shall be as shown in Table 18-29-604.5.

18-29-604.6 Variable street pressures.

   Where street water main pressures fluctuate, the building water distribution system shall be designed for the minimum pressure available.

18-29-604.7 Inadequate water pressure.

   Wherever water pressure from the street main or other source of supply is insufficient to provide flow pressures at fixture outlets as required under Section 18-29-604.3, a water pressure booster system conforming to Section 18-29-606.5 shall be installed on the building water supply system.

18-29-604.8 Water pressure reducing valve or regulator.

   Where water pressure within a building exceeds 100 psi (690 kPa) static at any fixture or outlet, an approved water pressure reducing valve conforming to ASSE 1003 with strainer shall be installed to reduce the pressure at any fixture or outlet in the building water distribution piping to 100 psi (690 kPa) static or less.

18-29-604.8.1 Reserved.

Editor's note – Coun. J. 12-14-22, p. 58278, Art. VI, § 8, as corrected by Coun. J. 4-19-23, p. 62477, § 1, repealed § 18-29-604.8.1, which pertained to valve design.

18-29-604.8.2 Repair and removal.

   All water pressure reducing valves, regulators and strainers shall be so constructed and installed as to permit repair or removal of parts without breaking a pipeline or removing the valve and strainer from the pipeline.

18-29-604.9 Water hammer.

   The flow of velocity of the water distribution system shall be controlled to reduce the possibility of water hammer. An air chamber or water-hammer arrestor shall be installed where quick-closing valves are utilized. Water-hammer arrestors shall be installed in accordance with the manufacturer's instructions. Water-hammer arrestors shall conform to ASSE 1010. Air chambers shall comply with Section 18-29-604.9.1.

(Amend Coun. J. 10-14-21, p. 37722, Art. VI, § 12; Amend Coun. J. 12-14-22, p. 58278, Art. VI, § 9; Amend Coun. J. 4-19-23, p. 62477, § 1)

18-29-604.9.1 Air chambers.

   An air chamber that is installed in a fixture supply shall be 12 inches (304.8 mm) in length and the same diameter as the fixture supply, or an air chamber with an equivalent volume may be used. An air chamber that is installed in a riser shall be 12 inches (304.8 mm) in length and at least the same diameter as the riser.

(Added Coun. J. 12-14-22, p. 58278, Art. VI, § 9)