18-29-604.1 General.

   The design of the water distribution system shall conform to accepted engineering practice. Methods utilized to determine pipe sizes shall be approved by the Commissioner of Buildings.

(Amend Coun. J. 11-8-12, p. 38872, § 349; Amend Coun. J. 10-14-21, p. 37722, Art. VI, § 5)

18-29-604.2 System interconnection.

   At the points of interconnection between the hot and cold water supply piping systems and the individual fixtures, appliances or devices, provisions shall be made to prevent flow between such piping systems.

18-29-604.3 Water distribution system design criteria.

   The water distribution system shall be designed, and pipe sizes shall be selected such that under conditions of peak demand, the capacities at the fixture supply pipe outlets shall not be less than shown in Table 18-29-604.3. The minimum flow rate and flow pressure provided at fixtures and appliances not listed in Table 18-29-604.3 shall be in accordance with the manufacturer's installation instructions.

Table 18-29-604.3
Water Distribution System Design Criteria Required Capacities at Fixture Supply Pipe Outlets

Fixture Supply Outlet Serving	Flow Rate a	Flow Pressure (psi)
Bathtub	4	8
Bidet	2	4
Combination fixture	4	8
Dishwasher, residential	2.75	8
Drinking fountain	0.75	8
Laundry tray	4	8
Lavatory	2	8
Shower	3	8
Shower, temperature controlled	3	20
Silkock, hose bibb	5	8
Sink, residential	2.5	8
Sink, service	3	20
Urinal, valve	15	20
Water closet, blow out, flushometer valve	35	25
Water closet, flushometer tank	1.6	20
Water closet, siphonic, flushometer valve	25	25
Water closet, tank, close coupled	3	8
Water closet, tank, one piece	6	20
Water closet, tank, pressure assist	3	25

 

For SI: 1 psi = 67.895 kPa, 1 gallon per minute (gpm) = 3.785 L/m.

a.   For additional requirements for flow rates and quantities, see Section 18-29-604.4.

(Amend Coun. J. 10-14-21, p. 37722, Art. VI, § 6)

18-29-604.4 Maximum flow and water consumption.

   The maximum water consumption flow rates and quantities for all plumbing fixtures and fixture fittings shall be in accordance with Table 18-29-604.4.

   Exceptions:

      1.   Blowout design water closets having a water consumption not greater than 3 1/2 gallons (13 L) per flushing cycle.

      2.   Vegetable sprays.

      3.   Clinical sinks having a water consumption not greater than 4 1/2 gallons (17 L) per flushing cycle.

      4.   Service sinks.

      5.   Emergency showers.

Table 18-29-604.4
Maximum Flow Rates and Consumption for Plumbing Fixtures and Fixture Fittings

Plumbing Fixture or Fixture Fitting	Maximum Flow Rate or Quantity a
Lavatory, private	1.5 gpm at 60 psi
Lavatory, public (other than metering)	0.5 gpm at 60 psi
Lavatory, public (metering)	0.25 gallons per metering cycle
Shower head b	2.0 gpm at 80 psi
Sink faucet	2.2 gpm at 60 psi
Sink faucet (residential kitchen)	1.8 gpm at 60 psi
Urinal	0.5 gallons per flushing cycle
Water closet	1.28 gallons per flushing cycle or equivalent dual flush c

 

For SI: 1 gallon = 3.785 L, 1 gpm = 3.785 L/m, 1 psi = 6.895 kPa.

a.   Consumption tolerances shall be determined from referenced standards.

b.   A hand-held shower spray is a shower head.

c.   A dual flush water closet where one third of the sum of the high flush volume plus twice the low flush volume is less than or equal to 1.28 gallons.

(Amend Coun. J. 10-14-21, p. 37722, Art. VI, § 7)

18-29-604.4.1 WaterSense compliance.

   New and replacement water closets, urinals, shower heads, weather-based irrigation controllers, spray sprinkler bodies, commercial pre-rinse spray valves and private residential lavatory faucets shall meet the specifications required for the United States Environmental Protection Agency's WaterSense program label and shall bear such label or be approved in accordance with this chapter.

(Added Coun. J. 10-14-21, p. 37722, Art. VI, § 8)

18-29-604.4.2 Reserved.

Editor's note – Coun. J. 10-14-21, p. 37722, Art. VI, § 9, repealed § 18-29-604.4.2, which pertained to water closets.

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)