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.

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 be not less than shown in Table 604.3. The minimum flow rate and flow pressure provided to fixtures and appliances not listed in Table 604.3 shall be in accordance with the manufacturer's instructions.

Table 604.3
Water Distribution System Design Criteria Required Capacity at Fixture Supply Pipe Outlets

Fixture Supply Outlet Serving	Flow Rate a (gpm)	Flow Pressure b (psi)
Bathtub, no shower	4	20
Bathtub with anti-scald protection	4	20
Bidet	1.5	20
Combination fixture	4	8
Dishwasher, residential	2.75	8
Drinking fountain	0.75	8
Laundry tray	4	8
Lavatory, private	1.5	8
Lavatory, private, mixing valve	1.5	8
Lavatory, public	1.5	8
Shower	2	8
Shower, balanced-pressure, thermostatic or combination balanced-pressure/thermostatic mixing valve	2 b	20
Sillcock, hose bibb	5	8
Sink, residential	2.2	8
Sink, service	3	8
Urinal, valve	18	20
Water closet, blow out, flushometer valve	25	25
Water closet, flushometer tank	3	20
Water closet, siphonic, flushometer valve	25	25
Water closet, tank, close coupled	3	15
Water closet, tank, one piece	3	20

 

For SI: 1 pound per square inch = 6.895 kPa, 1 gallon per minute = 3.785 L/m.

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

b.   Where the shower mixing valve manufacturer indicates a lower flow rating for the mixing valve, the lower value shall be applied.

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 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 604.4
Maximum Flow Rates and Consumption for Plumbing Fixtures and Fixture Fittings

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

 

For SI: 1 gallon = 3.785 L, 1 gallon per minute = 3.785 L/m, 1 pound per square inch = 6.895 kPa.

a.   A hand-held shower spray or body spray is a shower head.

b.   Consumption tolerances shall be determined from referenced standards.

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 per flush.

d.   The total flow of all shower heads in each shower compartment or bathing unit, in residential occupancies, shall be limited to 3 gpm operating simultaneously.

604.4.1 WaterSense program label required.

Showerheads, private lavatory faucets, water closets and for urinals, the urinal flush valve or fixture/valve combination, shall meet the specifications required for the WaterSense program label and shall bear such label, or shall be approved in accordance with this code.

604.5 Size of fixture supply.

The minimum size of a fixture supply pipe shall be as shown in Table 604.5. The fixture supply pipe shall terminate not more than 24 inches (610 mm) from the point of connection to the fixture. Each fixture supply shall have a stop valve. A reduced-size flexible water connector installed between the supply pipe and the fixture shall be of an approved type. The connector shall be used singularly. Coupling of two or more connectors shall not be allowed. The supply pipe shall extend to the floor or wall adjacent to the fixture. The minimum size of individual distribution lines utilized in parallel water distribution systems shall be as shown in Table 604.5.

Table 604.5
Minimum Sizes of Fixture Water Supply Pipes

Fixture	Minimum Pipe Size (inch)
Bathtubs	1/2
Bidet	3/8
Combination sink and tray	1/2
Dishwasher, 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
Water closet, flush tank	3/8
Water closet, flushometer tank	3/8
Water closet, flushometer valve	1
Water closet, one piece	1/2

 

For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm, 1 pound per square inch = 6.895 kPa.