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SECTION 4.303 INDOOR WATER USE

4.303.1 Twenty percent savings. A schedule of plumbing fixtures and fixture fittings that will reduce the overall use of potable water within the building by at least 20 percent shall be provided. The reduction shall be based on the maximum allowable water use per plumbing fixture and fitting as required by the California Building Standards Code. The 20 percent reduction in potable water use shall be demonstrated by one of the following methods:

1. Each plumbing fixture and fitting shall meet reduced flow rates specified in Table 4.303.2; or
2. A calculation demonstrating a 20 percent reduction in the building "water use" baseline as established in Table 4.303.1 shall be provided. For low-rise residential occupancies, the calculation shall be limited to the following plumbing fixture and fitting types: water closets, urinals, lavatory faucets and showerheads.

TABLE 4.303.1 WATER USE BASELINE1

FIXTURE TYPE
FLOW RATE2
DURATION
DAILY USES
OCCUPANTS3
Showerheads, residential
2.5 gpm @ 80 psi
8 min.
1
  
Lavatory faucets, residential
2.2 gpm @ 60 psi
.25 min.
3
  
Kitchen faucets
2.2 gpm @ 60 psi
4 min.
1
  
Replacement aerators
2.2 gpm @ 60 psi
      
Gravity tank-type water closets
1.6 gallons/flush
1 flush
1 male4
3 female
  
Flushometer tank water closets
1.6 gallons/flush
1 flush
1 male4
3 female
  
Flushometer valve water closets
1.6 gallons/flush
1 flush
1 male4
3 female
  
Electromechanical hydraulic water closets
1.6 gallons/flush
1 flush
1 male4
3 female
  
Urinals
1.0 gallon/flush
1 flush
2 male
  

Fixture "Water Use" = Flow rate × Duration × Occupants × Daily uses

1. Use Worksheet WS-1 to calculate baseline water use.

2. The flow rate is from the CEC Appliance Efficiency Standards, Title 20, California Code of Regulations; where a conflict occurs, the CEC standards shall apply.

3. For low-rise residential occupancies, the number of occupants shall be based on two persons for the first bedroom, plus one additional person for each additional bedroom.

4. The daily use number shall be increased to three if urinals are not installed in the room.