Thermostats on most residential water heaters have a temperature range between 90 to 150 degrees Fahrenheit. While most manufacturers have the notched center position of the thermostat dial in 120 degrees, some possess the center setting at 140 degrees. Scald injuries happen at temperatures of 140 degrees with just a six-second exposure to this water. Temperatures in that range are especially dangerous to children and the elderly who might not react quickly enough to eliminate themselves from the water before scalding. Additionally, higher water temperatures consume more energy and get rid of heat from the storage tank at a quicker rate.
How Hot Is Too Hot?
The U.S. Consumer Products Safety Commission recommends setting residential hot water heaters no higher than 120 degrees. This offers the best balance of cozy heat with safety and energy efficiency. In the average home, decreasing the water temperature from 140 degrees to 120 degrees can save as much as 10 percent on water heating costs.
When Hotter Is Required
Water heater temperatures below 140 degrees can present a slight possibility of toxic bacteria growth in the water heater tank. For households with people that are in a health risk of bacterial infection due to compromised immune systems or other infection, Water heater temperatures might be safely maintained above 140 degrees if an anti-scald mixing device is installed at the hot water output line leading to tubs, showers and taps.