Hot Water Temperature
Getting the proper hot water temperature setting on your water heater can be tricky.
The Center for Disease Control (CDC) recommends setting the temperature of your water heater to 120 degrees Fahrenheit. This is a setting that will prevent the build up of Legionella that can cause Legionnaire’s disease.
At the same time you should not go hotter than 120 degrees to prevent scalding. The following list shows the time in seconds for hot water at different temperatures (in Fahrenheit) to scald an adult and a child with third degree burns:
160 degrees – 1 second (adult), immediate (child)
150 degrees – 2 seconds (adult), 0.5 second (child)
140 degrees – 5 seconds (adult), 1 second (child)
135 degrees – 10 seconds (adult), 4 seconds (child)
130 degrees – 35 seconds (adult), 10 seconds (child)
125 degrees – 1.5 to 2 minutes
120 degrees – 5-10 minutes
How to Adjust Your Water Heater Setting
An example of a common water heater control is shown to the right. Generally, a setting of A or B is normal to get a safe temperature. Simply turn the knob until the notch is pointed at the A or B. You can then use a thermometer a few hours later to determine if it is at 120 degrees Fahrenheit or your desired temperature.
It is recommended to follow the manufacturer’s instructions on setting the temperature of the water heater. If you are unsure how to set the temperature, then consult with a qualified professional like a plumber.
