The Department of Energy recommends having your tank-based hot water heater set to 120 degrees
Fahrenheit for most people, but if you’ve never adjusted the temperature on your hot water heater, it’s probably set to 140 degrees, which is the default setting from most manufacturers.
When you get home, go to your hot water heater, remove the cover and turn it down to 120 degrees (sometimes labeled “hot” as opposed to “very hot”).
Not only does this switch save you money, it will also prevent you from getting scalded in the shower. You can expect to save about $20 a year from this simple switch.