Set Hot Water Heater Temperature at 120


Cost –  Free

Savings –  $12 – $30/year for each 10 degree reduction[1]

Installation time –  Varies

Materials/Tools –  Thermometer, marker

Maintenance –  None

         Although some manufacturers set water heater thermostats at 140F, most households usually only require them to be set at 120F, which also slows mineral buildup and corrosion in your water heater and pipes.  Water heated at 140F also poses a safety hazard, i.e., scalding.


1.    Measure the beginning temperature of your hot water using a thermometer at the tap farthest from the water heater.  Thermostat dials are often inaccurate.

2.    Mark the beginning temperature on your water heater thermostat with a marker, and then turn the thermostat down.

3.    Wait a couple of hours, and then measure the water temperature again at the farthest tap from the water heater.  Several adjustments may be necessary before you get the temperature you desire.

4.   If you are satisfied with the temperature, mark the new temperature on the water heater thermostat with a marker, so that you can make adjustments in the future if necessary.


       The American Academy of Pediatrics warns that setting the temperature above 120 degrees poses a significant risk of scald injuries.

       If you plan to be away from home for at least 3 days, turn the thermostat down to the lowest setting or completely turn off the water heater.  To turn off an electric water heater, switch off the circuit breaker to it.  For a gas water heater, make sure you know how to safely relight the pilot light before turning it off.