120 degrees Fahrenheit is the safety recommendation against scalding, but 140° is the common default setting. Most experts agree that anything below 120 degrees creates a risk for bacteria to develop inside your water heater from stagnant water, such as legionella that causes Legionnaire's disease.
In the US, the maximum legal temperature for a water heater in a residential setting is 120 degrees. Most folks want to run at 125-130 degrees but be careful. The Federal law that stipulates the max temperature is because of folks, especially kids, getting burned by the water.
The thermostat on your hot water cylinder should be set between 60 and 65 degrees. Setting it any higher than this means you're using more energy than is needed. Not only that, but you risk scalding yourself when using the hot water tap or shower.
The maximum Department of Energy recommended water heater temperature setting you should never exceed is 140 degrees Fahrenheit. The lowest recommended setting should never be below 120 degrees Fahrenheit.
Although some manufacturers set water heater thermostats at 140ºF, most households usually only require them to be set at 120ºF, which also slows mineral buildup and corrosion in your water heater and pipes. Water heated at 140ºF also poses a safety hazard—scalding.
What Temperature Should a Water Heater Be Set At? Most water heaters are designed to operate safely at temperatures between 120 and 160 degrees. Many tank-style units also have a low-temperature setting where the unit will only heat up the water to around 90 to 100 degrees.
"Hot water is typically described as approximately 110 to 140 degrees," says Channa Ovits, M.D., FAAD, a Westchester, New York-based board-certified dermatologist at Westmed Medical Group, a Summit Health Company. But in terms of a shower, you should never tiptoe over 120 degrees, due to the chance of a burn injury.
To help prevent bacteria growth, the ASSE recommends keeping the water in your water heater tank at about 135 - 140 degrees Fahrenheit.
According to most dermatologists, the ideal shower temperature is anywhere between 98°F (37°C) and 104°F (40°C)—and no more than 105 °F (41°C). Rinsing under lukewarm water allows you to stay comfortable and maintain your body temperature while reaping all the benefits of both hot and cold showers.
The Occupational Safety and Health Administration (OSHA) recommends a recommended hot water temperature of at least 122 degrees to prevent the growth of harmful bacteria. So, while setting the temp to 120°F may save on energy costs and avoid scalding, it's ideal to keep things a bit warmer for safety.
Keeping the temperature at a safe level, 60°C to 65°C, makes the water hot enough to use and hot enough to kill unwanted bacteria. To be on the safe side, hot water tanks are now required by law to be fitted with a thermostat to allow the temperature of the water in the tank to be set.
Ideally you should heat your home to a temperature of at least 18 °C. This is particularly important if you have reduced mobility, are 65 or over, or have a health condition, such as heart or lung disease. Having room temperatures slightly over 18 °C could be good for your health.
120 degrees Fahrenheit is the safety recommendation against scalding, but 140° is the common default setting. Most experts agree that anything below 120 degrees creates a risk for bacteria to develop inside your water heater from stagnant water, such as legionella that causes Legionnaire's disease.
If you opt to lower your water heater temperature, additional savings can come from the reduced energy required to heat the same amount of water to 120 degrees instead of 140 degrees. Experts also recommend turning down your water heater to its lowest settings if you plan to be away for an extended period.
We recommend always keeping the heater set between 110 and 120 degrees. In the summer, try setting your water heater temperature at the low end of this scale, placing it close to or at 110 degrees. In the winter, lean toward the high end of the range. During this season, 120 is a much more acceptable temperature.
The recommended setting for this control is 60°C/140°F. (Storing hot water at temperatures of less than 55°C is not advisable due to potential for Legionnaires disease). If the water coming out of your taps is too hot then check this control as it could be set too high.
Hot water needs to be stored above 60°C in hot water systems to prevent bacteria growth (such as Legionella), but a tempering valve ensures that the water comes out of the tap at a lower temperature.
It's generally much cheaper to heat water using your central heating system, rather than using electricity with an immersion. The exception might be during the summer, when you have your central heating turned off, or if you have an old inefficient boiler.
According to Centers for Disease Control and Prevention (CDC), water temperatures ranging from 130 to 140 degrees Fahrenheit(°F) can eliminate most of the harmful bacteria. However, be warned that these high temperatures can also increase the risk of scalding.
For instance, a typical shower uses about 10 gallons of hot water. So, if you have a 40-gallon hot water tank, you should be able to get four average-length showers out of your hot water tank. This also depends on how much hot water you use for other things.
The best temperature setting for a hot water heater is between 120 and 140 degrees. Below 120 degrees, bacteria can develop in the stagnant water sitting in the tank. Above 140 degrees, the water is so hot that you and your family members can be at risk for scalding in as little as two seconds.
The primary way most people notice their water heaters overheating is because the water becomes unbearably hot, scaldingly so. If your water heater is set on too high a temperature, burns, and severe injuries may occur.
If you're looking for a short answer, it's 120 degrees Fahrenheit (about 49 degrees Celsius).
Sediment Buildup
Water naturally has minerals and other sediments in it, and over time, these minerals and sediments build up in your water heater, which can cause you to run out of hot water faster than you did before.