Page 81 - WaterSense at Work

October 2012
less and thus are 20 percent more water-efficient than standard showerheads on the
market. In addition, WaterSense labeled showerheads are independently certified to
meet or exceed minimum performance requirements for spray coverage and force.
Except for communal settings in prisons, locker rooms, and barracks, avoid purchas-
ing and installing multiple showerheads when remodeling, particularly if they can
be operated simultaneously or so that the total volume of water flowing from all
showerheads is greater than the 2.0 gpmWaterSense specification maximum. These
multiple showerhead systems can waste a significant amount of water and energy.
Savings Potential
Water savings can be achieved by replacing existing showerheads. To estimate
facility-specific water savings and payback, use the following information.
Current Water Use
To estimate the current water use of an existing showerhead, identify the following
information and use Equation 3-7:
Flow rate of the existing showerhead. Showerheads installed in 1994 or later will
have a flow rate of 2.5 gpm or less. Older showerheads may flow as high as 3.0 to
Average duration of each shower. The average shower duration is approximately
eight minutes.
Average use rate of showers in terms of number of showers each person takes
per day.
Number of building occupants.
Days of facility operation per year.
Equation 3-7. Water Use of Showerhead (gallons per year)
= Showerhead Flow Rate x Duration of Use x Use Rate x Number of
Building Occupants x Days of Facility Operation
Showerhead Flow Rate (gallons per minute)
Duration of Use (minutes per shower)
Use Rate (showers per person per day)
Number of Building Occupants (persons)
Days of Facility Operation (days per year)
Mayer, Peter W. and DeOreo, William B. AmericanWater Works Association (AWWA) and AWWA Research Foundation. 1998.
Residential End Uses of Water
Page 102.