Hotter water is not just a comfort setting. It wastes energy and raises the risk of serious burns, especially for young children and older adults.
| Water temperature | Time to third-degree burn |
|---|---|
| 150°F | About 2 seconds |
| 140°F | About 6 seconds |
| 130°F | About 30 seconds |
| 120°F | About 5 minutes |
Why 120°F
DOE's home energy checklist recommends turning the water heater down to the warm setting, 120°F, to save energy and avoid scalding. CPSC reports that most tap-water scald victims are older adults and children under 5.
Factory settings and mixing valves
A.O. Smith ships its thermostats set at 120°F and warns that water over 125°F can cause severe burns instantly. Where someone in the home is at higher risk, the manufacturer recommends a mixing valve at the heater or the fixtures.
General information, not professional or legal advice; follow your manufacturer's manual, and your installer and local permit office have the final word. Sources:U.S. DOE FEMP, Home Energy Checklist; U.S. Consumer Product Safety Commission, tap water scalds (5098); A.O. Smith residential electric water heater manual (185762).
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