The EPA recommends setting your water heater to no higher than 120 degrees Fahrenheit. But OSHA recommends setting it to 140 degrees Fahrenheit. Why the difference?
“If you turn your water heater down to 120 degrees Fahrenheit; you will cut your water-heating costs by 6-10 percent,” says EPA. Doing so also uses less energy.
But 120 degrees is not hot enough to kill the Legionella pneumophila bacteria. Legionnaire’s disease causes both flu-like and pneumonia-like symptoms. The disease is most often caught by inhaling the spiral-shaped bacteria via water mist, such as in the shower or near a lake or stream. That’s why OSHA recommends setting your water heater hot enough to kill the bacterium – 140 degrees.
Legionnaire’s disease got its name when the Pennsylvania American Legion celebrated America’s 1976 bicentennial at a hotel with contaminated water. More than 200 people were treated for pneumonia. 34 died. The newly discovered Legionella pneumophila bacteria turned out to be the cause. That and other bacteria are why OSHA recommends 140 degrees.
EPA and OSHA are free to publish all the recommendations they want. But hopefully they won’t impose one standard or other on the entire country. One is expensive; the other would kill people.
Fortunately, you are still free to set your water heater how you choose. If you place a high value on saving money and energy, and you have your health, 120 degrees is the way to go. But if you are elderly or infirm, or you have children in your household, 140 degrees is probably better for you. When it comes to your water heater, you know best. Hopefully OSHA and EPA will continue to recognize that.
(via Sam Kazman)