What Temperature Should a Water Heater Be Set At? 120°F?
What temperature should a water heater be set at? About 120°F is the usual advice. See the scald and bacteria trade-offs, how to adjust it and how to test it.
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What temperature should a water heater be set at? Many manufacturers and safety agencies recommend about 120 degrees Fahrenheit (49 degrees Celsius), which is hot enough for everyday use, lowers scald risk and saves energy. Some households have health reasons to store water hotter and mix it down at the tap, so ask a professional if that applies to you.
What temperature should a water heater be set at: the trade-offs
Hotter water costs more to produce and scalds faster, particularly for children and older adults. At 140 degrees, a serious scald can take only a few seconds, while at 120 it takes much longer. On the other side, water kept too cool in a tank can allow bacteria such as Legionella to grow, which matters most for people with weakened immunity.
| Setting | Typical outcome |
|---|---|
| Around 120°F (49°C) | Common recommendation: comfortable, lower scald risk, lower energy use |
| Around 140°F (60°C) | Hotter and stronger against bacteria in the tank, but a higher scald risk without a mixing valve |
| Below 120°F | Saves energy but may encourage bacterial growth in the tank |
| Quick facts: what temperature should a water heater be set at | |
|---|---|
| Common advice | About 120°F (49°C) |
| Higher storage needs | A mixing valve to temper the water at taps |
| Check with | A thermometer at the nearest tap after two minutes |
| Turn power off first | Before opening an electric heater access panel |
How to check your current temperature
- Run the hot tap nearest the heater for about two minutes.
- Fill a cup and measure with a cooking thermometer.
- Compare the reading with the setting on the heater. Dials are often inaccurate.
- Repeat the test at a tap far from the heater to see how much heat the pipes lose on the way.
How to adjust the setting
Gas heater: turn the dial on the gas control to the temperature you want, or to a marked mid-point. Adjust in small steps and recheck after several hours.
Electric heater: turn off the breaker first. Remove the access panel and insulation, and set the thermostat on each element to the same value with a screwdriver. Replace the insulation and panel before restoring power. If you are not comfortable with this, ask an electrician or plumber.
Who should think carefully about a higher setting
People with weak immune systems, some medical conditions, or older adults in a household sometimes need advice from a doctor about Legionella risk. A common safe approach is to store hotter water and fit a thermostatic mixing valve so taps deliver tempered water. A plumber can install one. When you decide what temperature should a water heater be set at in your own home, weigh the health reasons and the scald risk together.
Dishwashers and other appliances
Many modern dishwashers have their own heating element to boost water temperature, so they do not rely on a very hot supply. Check your manual. If your dishwasher needs hotter water, a booster in the appliance is often a better answer than turning up the whole house.
Households with young children or older adults
Children and older adults have thinner skin and slower reactions, so the same water burns them faster. Keeping the heater near 120 degrees, and fitting anti-scald valves or thermostatic mixing valves at showers and tubs, adds protection that does not rely on anyone remembering to test the water. Teach children to turn on cold before hot and always test with a hand.
When you are away or the heater is rarely used
Some heaters have a vacation setting that holds the water cooler while you are away. This saves energy, but water that sits warm rather than hot in a tank can encourage bacteria, so run the hot taps for a few minutes when you return. For long absences, ask about turning the heater off, and restart it carefully on your return.
Signs the temperature setting is not the problem
If the water is lukewarm even at a high setting, or runs out fast, the issue may be sediment, a failing element or a broken dip tube rather than the dial.
Related reading
- How to Reset a Water Heater: Electric, Gas and Tankless
- Tankless vs Tank Water Heater: Which Fits Your Home?
- Hot Water Runs Out Quickly? 7 Causes and Fixes
- How Long Does a Water Heater Last? Lifespan and Warning Signs
Browse all plumbing guides, or find a plumber in your city from the plumbing directory.
Frequently asked questions
What temperature should a water heater be set at for safety?
About 120 degrees Fahrenheit is the common recommendation. It balances comfort, lower scald risk and energy use. Households with specific health concerns should ask a professional about storing hotter water with a mixing valve at the tap. That is a sensible starting point for most homes.
Is 140 degrees too hot for a water heater?
It can scald in seconds, especially children and older adults, unless a mixing valve tempers the water at taps. It does discourage bacterial growth in the tank. Many homes choose 120 degrees and add a mixing valve if they go higher.
How do I lower my water heater temperature?
On a gas heater, turn the dial on the gas control to a lower setting. On an electric heater, switch off the breaker, remove the panels, and lower each thermostat with a screwdriver. Recheck at a tap with a thermometer.
Does lowering the water heater temperature save energy?
Yes. A lower setting reduces the heat lost from the tank and the energy used to heat it. Moving from a higher setting toward 120 degrees is one of the simplest ways to cut hot-water energy use.
What temperature should a water heater be set at to prevent Legionella?
Storing water at higher temperatures discourages Legionella, while water kept cooler can allow growth. People at risk should get medical or plumbing advice, and a thermostatic mixing valve lets you store hotter water safely. A plumber can fit the valve.
How do I test the real temperature of my hot water?
Run the hot tap nearest the heater for about two minutes, fill a cup, and measure with a cooking or water thermometer. The dial on the heater is often inexact, so a tap reading is a better guide.
Why is my water not hot enough even at a high setting?
Sediment, a failed lower element, a broken dip tube or an undersized heater can leave water lukewarm. A mixing valve or a worn tempering valve can also dilute hot water. A plumber can test each part.
Do I need to turn off power to adjust an electric water heater?
Yes. Always switch off the breaker before removing the access panel, because the wiring behind it is live. Set both thermostats the same, replace the insulation and panel, then restore the power. Treat the wiring as live until the breaker is off and verified.
Is 120 degrees hot enough for dishwashers?
Many dishwashers have internal heaters that raise the water temperature, so 120 degrees at the tap is usually fine. Check your manual. If the dishwasher struggles to clean, check whether it has a booster heater setting before raising the water heater temperature.
Is a lower setting safer for children?
Yes. Water at 120 degrees takes much longer to scald than at 140 degrees. Consider anti-scald valves for extra protection. Many homes keep it at 120 degrees and add tempering valves at showers for extra protection, particularly with young children or older adults.
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