Last checked: October 21, 2026 · Applies to: U.S. homes with a gas or electric tank water heater

How to set your water heater temperature

Why it matters

• Burns happen fast. CPSC says most adults will get third-degree burns from 150°F water in two seconds, 140°F water in six seconds, and 130°F water in thirty seconds. Even at 120°F, five minutes of exposure can cause a third-degree burn. Most tap-water scald injuries and deaths happen to older adults and children under five. [1]
• It saves energy. The Department of Energy says water heating is the second-largest energy expense in a home, typically about 18% of energy use, and turning down the water heater thermostat is one of its main ways to cut that bill. [2]

When to do it

Any time of year. It's a good one to do alongside your fall checks, when you move into a home, when a baby or an older relative moves in, or after a plumber has worked on the water heater.

Checklist: test the water first

• Get a thermometer. A candy or meat thermometer works. [1]
• Pick the right time. Test first thing in the morning, or at least two hours after anyone has used hot water, so you get an accurate reading. [1]
• Run the hot water at the faucet closest to the water heater until it stops getting hotter, then hold the thermometer in the stream. [1]
• Read it. About 120°F? You're done; write the reading down (see the last step below). Above 120°F, keep going. Well below and you're running out of hot water? See "If it goes wrong" below.

Checklist: gas tank water heater

• Find the dial. On a standard gas water heater, the thermostat is part of the gas control valve near the bottom of the tank. [4]
• Turn it a little lower, following the markings on the dial. If it says "Low," "Hot," or letters instead of numbers, the manual explains what each mark means. [4] Lost the manual? Find the brand and model on the label on the tank (see where the label usually is), then search "<brand> <model> manual", putting in your own brand and model number.
• Digital display? Some newer models have buttons and show the exact temperature. Use the buttons to set it. [4]
• Not sure? CPSC suggests calling your gas company for instructions, since thermostats differ. [1]

Checklist: electric tank water heater

• Easiest option: CPSC says you can call your electric company to adjust it, and some offer this at no charge. [1]
• Turn off the power at the circuit breaker (or remove the fuse) for the water heater. [1] A. O. Smith also recommends confirming with a circuit tester that the power is really off. [4] Not comfortable around wiring? Stop here and call an electrician or plumber. [4]
• Open the access panels. Most electric heaters have an upper and a lower panel, each with a thermostat behind it. Remove the covers with a screwdriver and gently move the insulation aside. [1][4]
• Set the thermostat with a flat screwdriver, following the markings on it. If there are two thermostats, set both to the same temperature. [1][4]
• Close it back up: push the insulation back, replace the covers, then turn the breaker back on. [4]

Checklist: check your work

• Wait, then retest. A. O. Smith says to give it 30 to 60 minutes; CPSC's tip of testing first thing in the morning gives the most accurate reading. Adjust in small steps until the faucet reads about 120°F. [1][4]
• Check your dishwasher. The Department of Energy says if your dishwasher has its own heater that boosts water temperature, 120°F at the water heater is generally fine. Check your dishwasher manual for your model. [2]
• Write it down. On the Appliance Record page of the calendar PDF, fill in the Water heater row (brand / model # and where the manual is kept), and write today's date, the dial setting and your faucet reading beside it, so next time you know exactly where to set it.

Watch how: How to Adjust Water Heater Temperature (This Old House, YouTube; covers gas and electric tanks) · How To Change Temperature On A Water Heater (Ace Hardware, YouTube)

If it goes wrong / when to call a pro

• Running out of hot water at 120°F? A. O. Smith says you can turn it up a little, and if you want water hotter than 120°F, the safer way is a thermostatic mixing valve, which limits how hot the water gets at the faucet. A plumber can install one. [4]
• Someone in the home has a weakened immune system? A. O. Smith notes very low temperatures can let bacteria grow, and that homes with people at risk of waterborne illness may need a higher setting plus mixing valves. Ask their doctor and a plumber what's right for you. [4]
• No hot water at all after an electric adjustment? Check the breaker. If that doesn't fix it, call a pro. [4]
• Gas heater not heating, or turning on and off? Don't take gas parts apart. Call a qualified technician. [4]
• Renting or in an apartment? Ask your building manager to lower it. [1]
• Always hand-test bath water before bathing a baby or young child, and never leave a child alone in the bathroom, even for a second. [1]

Sources (fetched and checked October 21, 2026)

1. U.S. Consumer Product Safety Commission, Avoiding Tap Water Scalds (Publication 5098, PDF).
2. U.S. Department of Energy, Energy Saver Guide (PDF).
3. ENERGY STAR, Save Energy at Home (PDF).
4. A. O. Smith, Water Heater Temperature Settings.

Spotted something wrong or out of date? Tell us and we'll recheck it against the source.