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A Complete Guide To Ideal Water Heater Temperature

A Complete Guide To Ideal Water Heater Temperature

If you’re seeking a guide on the ideal water heater temperature, you’re in the right place.

We will cover the best settings to maximize safety and comfort.

Read on to learn all you need to know.

Why Hot Water Heater Temperatures Matter

A water heater, bills, and bacteria in a side by side graphic

When was the last time you changed your water heater temperature setting?

If you’re like most people, it’s probably been a while—or you’ve never touched the water heater thermostat.

It’s easy to set your water heater’s temperature to the perfect level, so there’s no danger of scalding or miserably lukewarm showers.

But what’s the perfect water heater temperature?

Whether it’s gas or electric, the hot water temperature in your house is set using the thermostat on your water heater.

Very Important Considerations

If you’ve never adjusted or paid much attention to your water heater’s temperature, now is a good time to change that. 

You might be spending hundreds more on energy costs or even promoting dangerous bacteria growth. 

You need to know about the different thermostat settings for the most comfortable hot water temperature and which option to select. 

Keep reading to see the ideal water heater temperature, the maximum temperature, and what happens if your water heater temperature is set either too low or too high.

We’ll also show you how to adjust your temperature and advise when it’s a good idea to call a professional for help.

Let’s get started!

What Is the Ideal Water Heater Temperature?

The ideal water heater temperature graphic showing pipes and 130 degrees in the below right corner

What’s the ideal water heater temperature? Most gas water heaters have the following temperature settings:

  • Low (Warm): 80-90°F
  • Hot (Triangle symbol): 120°F
  • A: 130°F
  • B: 140°F
  • C: 150°F
  • Very Hot: 160°F

Most electric water heaters have the temperature settings written out on the thermostat and require you to use a screwdriver to adjust the setting.

The Ideal Water Heater Temperature

While everyone has different temperature preferences, most people agree that about 130 degrees Fahrenheit is the ideal water heater temperature for both gas and electric water heaters.

The ideal water heater temperature range is 120°F to 140°F, depending on your preferences and hot water needs. When you purchased your water heater, chances are that the manufacturer set it at the OSHA recommended temperature of 140 degrees.

Why 140 Degrees?

At 140 degrees, the water is hot enough to sanitize and prevent bacterial growth, but it can potentially scald anyone exposed to it for more than 6 seconds. 

For this reason, we recommend turning the water heater temperature down to 130 degrees. This is hot enough to keep harmful bacteria from growing in your water heater, but cool enough to prevent scalding. 

If energy efficiency factors into your decision, consider the Environmental Protection Agency’s (EPA) recommendation of 120 degrees.

EPA Recommendations

The EPA recommends setting the temperature to 120 degrees because it uses less energy and is still hot enough to be comfortable.

However, it will not kill bacteria and creates the opportunity for dangerous bacteria to grow in your water heater.

Also, keep in mind that the temperature setting you use should consider any hot water appliances in your home that may need higher temperatures to sanitize effectively.

While 120 degrees is a pleasant temperature for hot water, it’s not hot enough to sanitize dishes or laundry.

Water Heater Temperatures Compared

Five thermostats in a side by side graphic with different temperatures for different things

Here’s a comparison of the different ideal water heater temperature settings and their pros and cons:

  • 120°F: Most energy-efficient and scald-safe, but won’t sanitize or kill bacteria and allows bacterial growth.
  • 130°F: Comfortable, somewhat energy-efficient, and scald-safe; kills bacteria in 6–8 hours and won’t allow bacterial growth.
  • 140°F: Very hot, ideal for sanitizing and killing bacteria, but has the potential to scald in less than 6 seconds.
  • 150°F: Extremely hot, ideal for sanitizing and killing bacteria, but will scald in less than 2 seconds.
  • 160°F: The hottest temperature setting on most gas water heaters, ideal for sanitizing and killing bacteria, but will scald on contact.

If you’d rather have the best of both worlds, you have two options. First, you can try setting the water heater temperature to 130 degrees, which is hot enough to sanitize but not enough to scald.

Second, you can use a hot water tank booster. This keeps the water in the tank at a bacteria-killing 140 degrees, but mixes it with enough cold water to bring it down to a safer, more comfortable 120 degrees at the tap. 

Things to Consider When Setting Water Heater Temperature

  • If you have young children or elderly people in your household, consider lowering the water temperature to 120°F to avoid scalding risk. 
  • If you have a dishwasher that does not preheat water, consider raising the water heater temperature to 140°F. 
  • If anyone in the household is immunocompromised, consider raising the water heater temperature to 140°F to ensure there is no opportunity for bacteria to grow. 
  • If you’re looking to save on energy costs, each 10°F you lower your water heater temperature saves about 3–5% on your energy costs. Just don’t go lower than 120°F.
  • If you have four or more people in your household, keep your water heater set to the high end of the ideal range (about 140°F) to ensure there is plenty of hot water to meet the increased demand. 

Is Your Water Heater Temperature Too Low?

How to test water heater temperature graphic

Your water heater has a thermostat you can adjust, but it probably doesn’t have a digital readout of the actual temperature. So how can you find out if your water heater temperature is too low?

There’s a simple way to find out:

  1. Grab a heat-safe cup and a cooking thermometer. Don’t use the hot water for at least one hour (and make sure no one else in the house does, either).
  2. Run the hot water at the tap closest to the water heater for about a minute to let it come to its maximum temperature, then fill the cup with hot water.
  3. Insert your cooking thermometer into the hot water and take a reading of the temperature. 

If your hot water is less than 120°F, you’ll need to adjust the thermostat to increase the temperature to a safe level.

Why Low Water Heater Temperatures Are Dangerous

Legionella bacteria naturally occurs in freshwater and is the main concern with too-low water temperatures. This is a type of bacteria that causes Legionnaires’ disease.

Water heaters can harbor this dangerous bacteria if they aren’t kept at the right temperature. Legionella thrives in the temperature range of 77°F–108°F, but it can survive in water up to 120°F.

Water that is 120°F can harbor Legionella, but at that temperature, the bacteria is prevented from growing and multiplying. 

However, anyone with a compromised immune system, including seniors 50 and older, anyone with a chronic disease, and current and former smokers, can become sick from drinking contaminated water.

For this reason, it’s best to stick to at least 140°F to ensure the water is hot enough to kill the bacteria entirely.

Is Your Water Heater Temperature Too High?

Showing someone putting their hand under the faucet and a thermostat

If you’ve had to jump back or remove your hand from the hot water in your home, it’s probably too hot. Try this to get an accurate reading of the water temperature.

Use a heat-safe cup and a calibrated cooking thermometer to test the water temperature. Stop using the hot water for at least one hour, or conduct this test first thing in the morning before anyone uses hot water. 

Go to the faucet nearest the water heater and turn the hot tap on, letting it run for a full minute to reach maximum temperature. Fill the cup with hot water, then use your cooking thermometer to measure the water temperature. 

If it’s above 140 degrees, you may want to reduce the temperature setting to 120°F–140°F. Too-hot water is dangerous. It can and will scald and cause burns on skin, sometimes on contact if the water is hot enough.

  • Opt for 120°F if you have non-immunocompromised young children or seniors in the home or want to maximize energy savings. 
  • Choose 130°F if you want comfortable water that is inhospitable to dangerous Legionella bacteria and hot enough to sanitize. 
  • Opt for 140°F if you have immunocompromised household members, more than four household members, or if your dishwasher doesn’t preheat the water it uses. 

How to Adjust Water Heater Temperature

Now that you know what your water heater temperature should be set to, it’s time to make the adjustments.

Adjusting the water heater temperature is easy, but the process is slightly different for electric and gas water heaters. Below are instructions for both.

How to Adjust Electric Water Heater Temperature

How to adjust an electric water heater temperature illustrated into a graphic

  1. Turn off the power to the electric water heater at the circuit breaker. 
  2. Locate the access panel that covers the thermostat(s) on your water heater. Remove the panel with a screwdriver. 
  3. Wear gloves to remove the insulation over the thermostat.
  4. Use a flathead screwdriver to manually adjust the thermostat temperature setting. You should see the different temperatures labeled on the thermostat, so turn in the direction you want to adjust the temperature to. 
  5. If your water heater has an upper and lower thermostat, adjust the other thermostat the same amount. You can even adjust the upper thermostat slightly higher than the lower one to ensure both heating elements inside the tank get enough use. 
  6. Replace the insulation you removed and screw the access panel back into place for one or both thermostats. 
  7. Turn the power to the water heater back on at the breaker. Wait a few hours to test the water and be sure it’s reached the correct temperature. 

If the water does not rise or fall to the correct temperature within 3–4 hours, you should call a professional to check out your water heater.

There may be a problem with your thermostat or another component inside the tank preventing the water from heating up.

Don’t make any further adjustments before the technician comes out to look at it. 

How to Adjust Gas Water Heater Temperature

How to adjust the water temperature of a gas water heater

  1. Locate your gas water heater’s thermostat dial. In older water heaters, it might be behind a removable access panel. For newer water heaters, you may see it directly on the outside of the tank. 
  2. Use a screwdriver to remove the access panel (if your water heater’s thermostat is behind one).
  3. Turn the thermostat dial to the proper temperature setting. Remember:
    1. “Low”: 80-90°F
    2. “Hot” (or triangle symbol): 120°F
    3. “A”: 130°F
    4. “B”: 140°F
    5. “C”: 150°F
    6. “Very Hot”: 160°F
  4. Screw the access panel back into place (if applicable) and wait a few hours before testing the water temperature to be sure it was properly adjusted.

If the water heater temperature doesn’t reach the setting you’ve adjusted it to within a few hours, you should call a professional. There could be a problem with the water heater components or the gas supply that powers it.

Don’t make any more adjustments before the technician comes out to inspect the water heater.

Find Your Ideal Water Heater Temperature

The ideal water heater temperature illustrated into a graphic

The ideal water heater temperature will be different based on your preferences and household needs. Finding the best water heater temperature for your household should take all of the following things into consideration. 

  • Household member ages: non-immunocompromised young children and elderly people may be more susceptible to scalding; set the temperature to 120°F.
  • Household member health: Anyone with chronic diseases or a compromised immune system needs the water set to 140°F to kill any Legionella bacteria in the water heater; use a hot water booster to keep the water at 140°F, but mix it with cold water at the tap to reduce the risk of scalding.
  • Household size: Households with four or more people usually have an increased demand for hot water, so set the temperature to 140°F to ensure there’s enough to meet demand.
  • Energy costs: If you’re trying to reduce your energy costs, reduce the temperature to 120°F for maximum savings, or lower it to 10°F from a higher temperature. Your energy costs go down 3-5% for each 10°F decrease.
  • Hot water appliances: If you have a dishwasher that doesn’t preheat the water to a high temperature, set the temperature to 140°F to ensure the water is hot enough to sanitize.

By taking each of these things into account, you’ll find your ideal water heater temperature somewhere in the range of 120°F to 140°F.

If all else fails, try setting it at 130°F and gradually raising or lowering the temperature based on your comfort level and needs.