What Temperature Should My Water Heater Be Set To?

Short answerSet it to about 120 degrees Fahrenheit. The Consumer Product Safety Commission urges that setting to prevent scalds, and A. O. Smith suggests the same, warning that lower settings can let bacteria grow. Even at 120, CPSC says a 5-minute exposure could cause third-degree burns, so test bath water by hand, especially for children.

How fast hot water burns

CPSC gives these times for third-degree burns in most adults.

150 degrees: 2 seconds.
140 degrees: 6 seconds.
130 degrees: 30 seconds.
120 degrees: 5 minutes.

Who's most at risk

CPSC says most injuries and deaths from tap water scalds involve the elderly and children under 5. It says to hand-test water before using it, especially for infants and young children, and it warns against leaving a child alone in the bathroom.

The two risks to balance

A. O. Smith says higher settings scald and lower settings let bacteria grow, which is why it lands on about 120. If someone in your home has a weakened immune system, we recommend asking a doctor. A. O. Smith's manual also shows a mixing valve set to 120 at the fixtures for hotter tank settings. A plumber can tell you if that fits your home.

How to adjust it

CPSC says to check the temperature at a faucet with a thermometer and follow your heater's manual. On electric models, CPSC says to shut off the circuit breaker before removing the access panels, or call your electric company. We don't give steps for gas controls, and CPSC says to call your gas company. CPSC notes that some homes get hot water from a furnace, so ask your fuel supplier, and renters should ask the building manager.

No Hot Water in House? What to Check First

Common questions

Can I save money by lowering it?

CPSC says lowering to 120 will conserve energy and save money. We wouldn't go much lower, given A. O. Smith's warning about bacteria.

My dishwasher needs hotter water. What do I do?

CPSC says to choose the lowest setting that meets your clothes and dish washing machines' needs. Check the appliance's manual, and ask a plumber about a mixing valve if you need the tank hotter.