What Temperature Should the Water Heater Be Set So the Water Will Not Burn a Child?

This is the seventh in a series of questions asked of grandparents to see how close they could get to the recommendations of the American Academy of Pediatrics on child safety and nutrition (AAP).

English: Southport, NC, October 4, 1999 -- Ele...

Hot water heater. Photo By DAVE SAVILLE/ FEMA News Photo (Photo credit: Wikipedia)

On this question they did poorly.

But, it is likely that they were trying to be safer and just didn’t know how hot the water in a house usually is.

This is the question.

See how you do.

What temperature should the water heater be set to so the water will not burn a child?

  • 85 degrees Fahrenheit (85.1% of the grandparents surveyed picked this answer)
  • 100°F (6.4%)
  • 120°F (8.5% picked this answer, the right one)

85 degrees would actually make for a cold shower, since average body temperature is 98 degrees.

Dr. Amanda Soong, pediatrician, professor and mother of two, recently conducted a survey to uncover whether grandparents are up-to-date on AAP recommendations

She found that they largely were not.

However, in this case, she believes that grandparents were wrong because they were just thinking about what might be the safest water temperature and picked the lowest number.

Temperatures of 140-150°F, where our water heaters used to be set at the factory, cause a third-degree burn for adults in two to five seconds.

It is faster for children.

At 120-125°F, by contrast, it takes 30 seconds to 10 minutes for an adult to be burned.

In the face of a number of states mandating temperatures below 140°F in the early 1980s, helped by AAP efforts, the Gas Appliance Manufacturers Association set a voluntary preset factory limit of 120 degrees Fahrenheit.

The electric hot-water heater industry followed suit with a voluntary standard of 125 degrees Fahrenheit, preset at the factory.

What Happens at Different Temperatures?

Scalding is related to how hot the temperature of the liquid is and how long the skin is exposed to it.

Water at 111°F (44° C) takes six hours to cause a first-degree burn (sunburn)

For each degree Celsius above that, the time required to cause a burn is cut in half.

At 120° F (49 degrees Celsius (C), it takes 5 to 10 minutes to cause a full thickness (third degree) burn in adults.

  • At 124°F (51°C), four minutes
  • At 125°F (52°C), two minutes
  • At 130°F (54°C), 30 seconds
  • At 140°F (60°C), five seconds
  • At 150°F, (66°C), two seconds for a third-degree burn in adults
  • At 158°F (70°C), less than one second.

Before our water heater temperatures were changed at the factory, scalding burns often were the result of unsupervised children under 5 or seniors over 65 who could not get out of a tub fast enough to avoid being burned, especially dangerous because so much of the skin is injured.

Giving them more time helps reduce the number of unintentional scaldings.

Follow-up studies suggest that about eight percent of homeowners raise the factory setting.

Homeowners can change the setting if they want hotter showers or are worried about something like Legionnaire’s Disease being harbored in their water heater, but should know that hotter temperatures can burn sensitive skin, like that of children or seniors.

After the voluntary change in temperature to 120°F or 125° and public education measures alerting people to the risks of hot water, admissions to hospitals for children’s scalding burns dropped by 50%.

You can check the temperature of your own hot water heater by following instructions at water-heater-repair-guide.com.

You can also install faucet regulators that keep a child from turning the faucet all the way to the maximum temperature.

What About Dishwashers?

Many recommend that water in dishwashers be set to 140°F for proper cleaning.

Most dishwashers, however, have a booster that raises the incoming water temperature to 140°F, so it doesn’t hurt to have the incoming temperature at 120°F.

Manufacturers suggest you run the  tap until it gets hot before turning on the dishwasher.

What Does Canada Do?

There is a difference of opinion on this question between the U.S. and Canada.

The difference has to do with balancing the risk of burning a child who turns the water on as hot as it will go and the risk of the water in your hot water tank becoming a place where Legionnaire’s Disease can grow.

While Legionnaire’s Disease grows best between 90°F (32°C) and 95°F (35°C), there is no growth above 131°F (55°C) and over 140°F (60C) the heat kills bacteria.

Because of this, the World Health Organization recommends that water temperature on water heaters be set at 140°F (60°C).

Studies in Quebec, however, have shown that even when the temperature is set at 140°F (60°C), there can still be growth because of the lower temperature at the bottom of the tank.

40% of electric water heaters in Quebec were found to be contaminated with Legionnaire’s Disease.

In 2004, Safe Kids Canada recommended reducing preset factory water heater temperatures to 120°F (49°C) because of the risk of scalding.

Dr. Benoit Levesque, Fellow of the Royal College of Physicians of Canada, among other Canadian doctors, has recommended following the WHO recommendations of 60°C, with anti-scald devices at the tap because of the risk of Legionnaire’s Disease.

The conversation within Canada continues.

But, the conversation in the U.S. is settled.

Your hot water heater, delivered from the factory, will be set at 120F or 125F.

Turning it up is up to you.

Click on Soong to hear an audio interview with Dr. Amanda Soong Q7 water heater on this question.

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Have you ever found your hot water not hot enough?

Do you test the water in the bathtub before you let your grandchildren step in?

Do you know anyone who has been burned from water that was too hot?

To you and protecting your sensitive grandchildren.


Carol Covin, Granny-Guru

Author, “Who Gets to Name Grandma? The Wisdom of Mothers and Grandmothers



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