Do you know at what temperature your water heater is set? Safety and personal preference dictate how high to set the thermostat. Oregon code suggests a setting of 125 degrees Fahrenheit. Washington’s is five degrees lower at 120. Many experts advise 120 degrees as the ideal to prevent scalding.

Why Is 120 Degrees the Best Water Heater Temperature?

Water heaters that are set too high increase the risk of scalding. The U.S. Consumer Product Safety Commission (CPSC) in 1988 recommended manufacturers set heaters for a maximum of 120 degrees Fahrenheit. At this temperature the chance of a tap-water burn is reduced.

While manufacturers voluntarily agreed to this setting, in practice thermostat settings vary. According to, some water heaters are set at 140 degrees. Water that hot can cause a burn in as little as six seconds. Children and the elderly are at increased risk of injury from hot water.

A setting of 120 degrees is right for most households. The ideal temperature for a shower is 112 degrees according to a recent article in The Wall Street Journal. Water at that temperature washes away dirt and bacteria and feels comfortably warm to most people.

How Does a Lower Setting Save Money?

Keeping the thermostat setting at a maximum of 120 degrees also saves money. You can save between 12 and 30 dollars annually for a 10-degree reduction in thermostat temperature, according to In addition, a lower setting slows mineral buildup and corrosion in water heaters and pipes. Your water heater can potentially last longer when you turn down the thermostat.

Why Do Some People Prefer a Higher Setting?

Dishwashers need water at 130 to 140 degrees Fahrenheit for optimal cleaning. Most dishwashers have a booster heater to ensure water gets hot enough, but some may not.

With water lower than 140 degrees, there is a slight risk of legionellae bacteria growing in plumbing systems. For people with a suppressed immune system, a setting of 140 may be recommended. If you set your thermostat higher than 120, you can install a mixing valve or temperature-regulating device on household taps. These devices protect people from burns, while still allowing for water hot enough to kill bacteria.

Can You Go Too Low?

Some people turn the thermostat as low as 100 degrees in order to reduce energy use. Bacteria won’t be killed if temperatures are too low. If you’re interested in conserving water and energy, consider a high-efficiency water heater and low-flow fixtures.

How to Test Water Temperature

To the water temperature in your house, run the hot water tap. Fill a glass and drop in a candy thermometer. Consult the manual for your water heater to make an adjustment. Make slight changes to the thermostat and retest the water temperature in 24 hours.

Some types of heaters are easier to adjust than others. If you need help with your water heater, Meticulous can help. Contact us today!

Recommended Posts