Is 140 too high for a water heater?

Author: Mattie Hansen  |  Last update: Sunday, March 23, 2025

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.

Is 140 degree water too hot to touch?

If the temperature is set above a safe threshold, such as 140 degrees Fahrenheit, the risk of scalding increases significantly. This can cause painful burns and other serious injuries, especially for children or older adults with more sensitive skin.

How high is too high for a water heater?

Even though most units will go up to 160 degrees, you really shouldn't ever set the temperature higher than 140 degrees in order to reduce the risk of scalding. The EPA recommendation is to always leave your water heater set to 120 degrees.

Can you shower in 140 degree water?

If you are taking a shower or a bath you can receive severe burns because of scalding hot water. At 140°, water takes only a few seconds to cause third-degree burns, which penetrate the skin and can create permanent scarring.

Is 145 too hot for a water heater?

Children and older people, who typically have thinner skin, suffer more severe burns in a shorter time and at lower temperatures than adults. A child can suffer a third-degree burn in 124°F water in less than three minutes. Children and adults can be burned this badly in two seconds or sooner in 149°F water.

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Is it safe to set your water heater at 140?

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.

Is 140 too high for water heater?

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.

What happens if the water heater is set too high?

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.

Is 150 too hot for a water heater?

At 150 degrees, which is definitely way too hot, it takes only seconds for the water to cause third-degree burns.

Does 140 degree water sanitize?

It takes only 32 minutes on average for Legionella to die at temperatures of 140 degrees, and at 151 degrees, the bacteria will die instantly. This is why disinfection that uses temperature change will set a water heater to approximately 158 degrees for five minutes.

How do I know if my water heater is too hot?

How do you know if your water heater is too hot? The easiest way to test your water temperature is to run hot water from your faucet for 3 minutes and fill a glass of water. Insert a thermometer into the water and check the reading, if its is over 120 degrees the water is too hot and can potentially cause burns.

What is the maximum safe temperature for a water heater?

120 Degrees is the recommended max temperature for water heaters, according to both the American Society of Sanitary Engineering and the US Department of Energy. Firstly, setting the max temperature to 120 degrees prevents the water from scalding your skin.

How high can you safely turn up water heater?

120 degrees Fahrenheit is the safety recommendation against scalding, but 140° is the common default setting.

Is it bad to turn your hot water heater all the way up?

Yes, it's very bad to turn your water heater all the way up. To do so will reduce its life, increase your electricity bill and could possibly cause scalding—particularly if you have young children or an elderly relative living in your home.

What happens to water at 140 degrees?

At 140 degrees Celsius, water is in a superheated state, which means that it exists in a gaseous phase rather than a liquid phase. The pressure of water in this state depends on its specific volume, temperature, and other properties such as its internal energy and entropy.

Is 140 degree water boiling?

The boiling point of water is 212 degrees Fahrenheit or 100 degrees Celsius at sea level. That means in most places this is the temperatures of boiled water.

Is 135 OK for water heater?

To help prevent bacteria growth, the ASSE recommends keeping the water in your water heater tank at about 135 - 140 degrees Fahrenheit.

What does a and b mean on a water heater?

Understanding these settings can help when figuring out how to adjust the temp on water heater units. A typically represents around 130°F. B usually corresponds to 140°F. C indicates a temperature of about 150°F or higher.

How hot should hot water be coming out of a faucet?

The U.S. Consumer Product Safety Commission (CPSC) urges all users to lower their water heaters to 120 degrees Fahrenheit. In addition to preventing accidents, this decrease in temperature will conserve energy and save money.

Is it okay to set a water heater to 150?

The temp you are leaning toward is scalding hot and could hurt some one. If you have a mixing valve installed, the tank needs to be about 20 degrees hotter than the mix valve setting. So 140- 145 is adequate, with a 120 setting on the valve. Unless you need more drawdown, no need to go above 140 or so.

Can hot water heater cause high water bill?

Faulty fixtures or leaking connections and pipes can go unnoticed at the water heater because it is not an appliance you see every day. The leaks can become significant and result in an increase in the water usage bill and your energy usage bill.

Is 130 too hot for a water heater?

What's the Optimal Hot Water Heater Temperature? Most hot water heaters are set at the factory setting of 140 degrees Fahrenheit, but this isn't necessarily the best temperature for it. The United States Department of Energy recommends that most people set the temperature at 120 degrees Fahrenheit.

Should I set my water heater to 140 degrees?

Most homeowners will not need to worry about this, since water at 120 degrees will eliminate most common bacteria. However, 140 degrees is needed to kill a rare and specific strain, Legionnaires' disease bacteria, which causes a very serious pneumonia-like sickness.

Is 145 safe for a water heater?

The lower the temperature, the greater the safety and savings in energy cost. To achieve this, we recommend a temperature setting of 120°F or less. Water temperatures over 125°F can cause severe burns instantly or death from scalds.

What happens if your water heater temperature is too high?

While water heaters are designed to heat up water, doing this excessively can be dangerous. For instance, water temperatures that reach more than one hundred and forty degrees Fahrenheit can easily cause skin burns that are so severe you might require surgery.

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