Water Use After Retrofit or Replacement
To estimate the water use after retrofitting or replacing an existing faucet with a
water-efficient model or aerator, use Equation 3-5, substituting the flow rate of the
retrofit or replacement. WaterSense labeled aerators installed in private-use settings
use no more than 1.5 gpm. Public-use lavatory faucets can be retrofitted with 0.5
To calculate water savings that can be achieved from retrofitting or replacing an
existing faucet, identify the following information and use Equation 3-6:
Current water use as calculated using Equation 3-5.
Water use after retrofit or replacement as calculated using Equation 3-5.
Equation 3-6. Water Savings From Faucet Retrofit or Replacement
gallons per year)
= Current Water Use of Faucet –Water Use of Faucet After Retrofit or
Current Water Use of Faucet (gallons per year)
Water Use of Faucet After Retrofit or Replacement (gallons per year)
To calculate the simple payback from the water savings associated with the lavatory
faucet retrofit or replacement, consider the equipment and installation cost of the
retrofit or replacement faucet or aerator, the water savings as calculated using Equa-
tion 3-6, and the facility-specific cost of water and wastewater. Aerators typically cost
$10 and require no installation cost.
Because faucets use hot water, a reduction in water use will also result in energy
savings, further reducing the payback period and increasing replacement cost-
Alliance for Water Efficiency. Faucet Fixtures Introduction.
EPA’s WaterSense program. WaterSense Labeled Sink Faucets & Acessories.