# Page 254 - WaterSense at Work

7-36
October 2012
Equation 7-11. Water Use of Cage, Rack, Bottle, or Tunnel Washer (gallons per year)
=Water Efficiency x Number of Loads x Days of Operation
Where:
••
Water Efficiency (gallons per load)
••
Number of Loads (number of loads per day)
••
Days of Operation (days of cage, rack, bottle, or tunnel washer opera-
tion per year)
Water Use After Replacement
To estimate the water use after replacing an existing cage, rack, bottle, or tunnel
washer, use Equation 7-11, substituting the water efficiency of the replacement
washer. The water efficiency of the replacement washer should be provided by the
product manufacturer. More recent models of washers can use up to 90 percent less
water per load when compared to older, less efficient units by reusing rinse water
and having shorter rinse and wash cycles. If the number of rinse cycles can be se-
lected, base the water use on the water efficiency associated with the average fewest
number of rinse cycles needed for effective washing operations.
Water Savings
To calculate the water savings that can be achieved from replacing an existing cage,
rack, bottle, or tunnel washer, identify the following information and use Equation 7-12:
••
Current water use as calculated using Equation 7-11.
••
Water use after replacement as calculated using Equation 7-11.
Equation 7-12. Water Savings From Cage, Rack, Bottle, or Tunnel Washer
Replacement (gallons per year)
= Current Water Use of Cage, Rack, Bottle, or Tunnel Washer –Water Use
After Cage, Rack, Bottle, or Tunnel Washer Replacement
Where:
••
Current Water Use of Cage, Rack, Bottle, or Tunnel Washer (gallons
per year)
••
Water Use After Cage, Rack, Bottle, or Tunnel Washer Replacement
(
gallons per year)
7.7
Vivarium Washing and Watering Systems