How to control the temperature on a hot water tank

Updated February 21, 2017

Learn how to control the temperature on a hot water tank to make sure household water temperature is set properly. Hot water temperature at the tank should be no cooler than 55 degrees Celsius (130 degrees Fahrenheit). Any hotter may result in scalding and unnecessarily high water bills, but any cooler and the water may breed disease. Controlling the temperature at the tank is the only way to ensure the temperature is exactly where it should be.

Locate the metal plate covering the hot water tank thermostat and remove it by unscrewing the screws with a screw driver.

Look at the thermostat reading to see at what temperature the hot water is currently set, then adjust it up or down depending on the needs of the household while remembering that 55 degrees Celsius (130 degrees Fahrenheit) is the recommended setting.

Test the temperature of the hot water at any of the inside water taps by turning on the hot water and letting it run for a minute or two to get hot, then filling a drinking glass with the water and setting a cooking thermometer in the water. Let the thermometer sit for a few minutes and then note the reading.

Fine tune the thermostat at the hot water tank if necessary, then reattach the metal cover over the tank's thermostat.

Call a plumber if the setting on the hot water tank thermometer and the temperature of the tap water varies more than 6 degrees Celsius (10 degrees Fahrenheit), as this may indicate a malfunction in either the heater or the heater's thermostat.

Things You'll Need

  • Hot water tank
  • Hot water
  • Cooking thermometer
  • Drinking glass
  • Screw driver
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About the Author

An attorney for more than 18 years, Jennifer Williams has served the Florida Judiciary as supervising attorney for research and drafting, and as appointed special master. Williams has a Bachelor of Arts in communications from Jacksonville University, law degree from NSU's Shepard-Broad Law Center and certificates in environmental law and Native American rights from Tulsa University Law.