Recently while repairing a water heater in a West Chester home, we were asked by the homeowner about the best temperature for a domestic water heater. It’s a question we hear a lot, with a surprisingly complicated answer. 

Not Too hot, Not Too Cold

When considering the best temperature for the water heater in your Cincinnati home there are two main factors to take into consideration. A water temperature that is too hot can quickly result in scalding or burning. A water temperature that is too cold

Opposing Opinions

The environment protection agency currently recommends setting the temperature of your water heater to 120 degrees Fahrenheit, suggesting it will save energy and could cut your water heating cost by as much as 6 to 10%.  Many child safety organizations also suggests 120 degrees as a safe water temperature.  The experts at healthcentral note that many scald injuries are the result of water heaters being set above 120 degrees, and that a hot water temperature of 140 degrees F can cause a full-thickness burn in 10 seconds.

But before rushing to adjust the temperature on your unit, you must also take into consideration the advice of the United States Department of Labor Occupational Safety & Health Administration. OSHA suggests that maintaining a water heater temperature of 140 degrees F will prevent the over growth of the disease causing bacteria Legionella. Preventing the growth of Legionella may be of especial concern in homes with people at high risk of contracting the disease legionellosis, such as people with weakened immune systems and the elderly.

According to the paper Legionella and the prevention of legionellosis, found at the World Health Organization website, temperature affects the survival of Legionella as follows:

• Above 70 °C (158 °F): Legionella dies almost instantly
• At 60 °C (140 °F): 90% die in 2 minutes
• At 50 °C (122 °F): 90% die in 80–124 minutes, depending on strain
• At 48 to 50 °C (118 to 122 °F): Can survive but do not multiply
• 32 to 42 °C (90 to 108 °F): Ideal growth range

An Ideal Solution

As you can see, choosing the correcting temperature for the water heater in your home is less the straightforward. Determining the right temperature will depend greatly on the people living in your home and whether scalding and burns or bacterial overgrowth are a larger concern for you and your family. There is however one solution that addresses both of these concerns:  setting the water heater to to a higher temperature to prevent the growth of harmful bacteria and installing anti-scalding devices at each point of human contact with the water (sinks, bathtubs, shower heads etc). Anti-scalding devices are easily installed, allow you to set the water heater temperature high enough to prevent Legionella from multiplying,  and can be equipped on any water supply to restrict water from the faucet to the safe temperature of 120 degrees.

What’s the temperature of your home water heater? Let us know in the comments below!