As you know, modern hot water systems allow you to set the maximum temperature of hot water coming out, either by using less gas/electricity or by mixing the hot water with cold water to the set temperature.

We have baby (our first) arriving in 2 weeks and we probably should revise our hot water setting down from 50°C (which my husband likes to leave it at for doing dishes of all things!) All the books and anecdotal baby advice recommend utilising the temperature setting on the hot water system to avoid children, especially babies, accidentally being burned.

I've read conflicting advice for the right, kid-safe temperature. At the low end, one book suggests 38°C, which is basically just body temperature. At the other end, my husband and I like to shower at around 44°C (which we do by turning on a cold tap and manually mixing which is probably stupid). Apparently it takes a couple of minutes for a kid to get badly burnt at 50°C but just a couple seconds for third degree burns at 60°C so some kind of tradeoff might be in order below 50°C. Would 44°C be safe? What would you set it at?

Answers in °C preferred.

3 Answers 3


48-50C (118-120F) should be fine as a max temperature, according to Baby Center. As a rule, you should always test the water on a sensitive part of your body, such as the inside of your wrist or elbow.

The linked article mentions that babies generally like it cooler, but your experience may vary. My son actually preferred it warmer (to clarify - not "hot" per se, but a warmer temperature than what we expected at first) even when he was a young infant (he's almost 4, now, and his bath is the same temperature setting as our shower). So, also use your baby as a guide - if s/he shows signs of being cold, make the bath warmer, if s/he seems to feel like it's too hot, cool it down.

  • There is some concern it should be higher to prevent bacteria, but 49C is a common consensus for a balance. lifehacker.com/…
    – AaronM
    Apr 23, 2014 at 3:29
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    @aaronm - the CDC says that temperature of water doesn't make much difference for bacteria removal. Scallds and burns hospitalise 300 children per day (over 100,000 people per year) and kills two children per day (over 700 children per year) in the US. Compare that to legionella, which hospitalises maybe 18,000 people per year with a 5 to 30% death rate.
    – DanBeale
    Apr 23, 2014 at 8:44
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    How many of those scalds and burns are from the tap water vs a spilt boiling pot of water or superheating water in the microwave? I've burned myself plenty of times, never from the hot tap water. I think you may be comparing apples and oranges is all I am saying. I think having to boil water to do dishes might be a greater risk than having hot tap water.
    – AaronM
    Apr 23, 2014 at 16:48
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    People die from hot tap water. People need skin grafts because of burns caused by hot tap water. The reason you might not have been burnt is because CDC and other national standards bodies set max water temp from taps to be something that will scald after minutes, not instantly. Since this site is mostly about children we need to remember to keep the temperature lower because thin skin means they burn quicker and small body size means a greater percentage of their body will be burnt.
    – DanBeale
    Apr 26, 2014 at 19:36
  • @DanBeale - The StackExchange sites are also about factual information with cited sources. Do you have statistics for burns from hot tap water vs water that was heated on a stove or in a microwave? Without it or similar statistics, all you're doing is playing to emotions. Most people don't want to harm their children, certainly, but knowledge is far better than fear.
    – Shauna
    Apr 28, 2014 at 15:04

You don't want too low a temperature due to the possibility of legionnaires' disease. However, the hotter the water, the more quickly a burn will occur.

Notably, children don't have quick reaction times to pain - they don't always jerk their hands away reflexively from a heat source.

It can take less than 3 seconds to sustain a 3rd degree burn from 145F (63C) water, but it can take 5 minutes or longer to sustain a 3rd degree burn from 120F (49C) water.

As such, the Consumer Safety Product Commision (CPSC) and the American Academy of Pediatrics recommends that hot water heaters in homes with children (and elderly) be set no higher than 120F (49C).

At that temperature Legionnaires' disease is low risk, and if your water supply is pre-treated then the risk is negligible. Much lower than 120F (49C), however, and this anaerobic bacteria can multiple in the water pipes faster than they would in the cold water pipe.

Beyond the temperature setting of your hot water heater, you can install anti-scald devices which limit the temperature at the faucet. You can also install a thermostatic mixing valve at the output of the hot water heater, and leave the heater at a higher temperature. The heater can then be at, perhaps, 140F (60C), but the mixing valve will automatically mix cold water at the output so the water at the faucets goes no higher than 120F (49C). This can give you more apparent hot water if you find yourself running out of hot water frequently.

Remember, however, that the best defense against injury due to hot water is your own presence. Don't let children be unattended in areas where they have access to hot water.

  • Your Celsius conversions are off somewhere. Your 145F and 120F both say 49C.
    – Shauna
    Apr 28, 2014 at 15:05
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    +1 for the faucet-level limiters. Those have the added bonus of allowing the water temperature to be set higher for high-heat uses (dishwasher, etc), and keep it lower for places with a high burn risk (the tub the kids use, etc).
    – Shauna
    Apr 28, 2014 at 15:10

US CDC recommends 120F, which is 48.8 C http://www.cdc.gov/safechild/Burns/

Hotter temperatures are not much use for killing bacteria. Bacteria are dealt with by mechanical action or bactericides, not hot water. Warmer water might help with removal of dirt. Don't forget that hot water (and soap) can damage skin and that's likely to cause conditions where germs can lurk. http://www.cdc.gov/handwashing/show-me-the-science-handwashing.html

You may find that setting the thermostat lower allows you to run a shower at a safe temperature even with no cold water mix. Your husband can boil a kettle to wash the dishes; or could run the hot tap slower which will tend to raise the temperature of the water.

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