Water Heater Temperature - All You Need to Know about It

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Last updated: 
April 23, 2024

Adjusting Your Water Heater Temperature: Finding the Sweet Spot

The sweet spot for water temperature reduces the risk of scalding but delivers enough hot water for your household demand. Not too hot, and not too cold. Call it the Goldilocks setting! This guide gives step-by-step instructions for adjusting water heater temperature to the optimum setting.

According to the U.S. Consumer Product Safety Commission (CPSC) and the Department of Energy, setting your water heater to 120°F offers both safety and reduced energy consumption while providing sufficient hot water. While some manufacturers suggest setting water temperature to 140°F, this can cause third-degree burns in just three to five seconds and increases standby heat loss. On the other hand, setting the thermostat as low as 100°F could result in running out of hot water during peak demand.

Steps to Adjusting Water Heater Temperature

Here's an overview of how to adjust your water heater temperature to 120°F:

  1. Check the current water temperature using a thermometer
  2. Locate the thermostat on the water heater
  3. Mark the current thermostat setting
  4. Adjust and mark the new thermostat setting
  5. Recheck the water temperature after waiting for the water heater to adjust

Step 1: Check the Current Water Temperature

For tank-style water heaters, avoid using hot water for 30 minutes before checking the temperature to ensure the water is completely heated. Run the tap farthest from the water heater long enough to get the hottest water possible. Fill a mug and place a food thermometer's probe in the water. It might take up to 20 seconds to reach the full temperature.

Step 2: Locate the Water Heater Thermostat

The location of the thermostat varies depending on the type of water heater:

  • Gas tank-style water heater: The thermostat is on the outside of the tank near the bottom of the unit, marked with temperature indicators such as "Very Hot" and/or letters A, B, and C.
  • Electric tank-style water heater: Most electric water heaters have two heating coils (top and bottom) and two thermostats, each found behind a raised cover with one or more screws. Remove the cover and any fiberglass insulation covering the thermostats.
  • Tankless water heater: Most tankless units have the thermostat dial or a digital temperature display on the outside front of the unit.

Step 3: Mark the Current Thermostat Setting

Before adjusting the water temperature, mark the current setting as a reference point. Use a dry erase marker or a small piece of tape to mark the setting on gas and electric models. For digital thermostats, jot down the current setting.

Step 4: Adjust and Mark the New Thermostat Setting

Many water heater thermostats have five marks on the dial:

Very Hot160°F

To adjust the temperature:

  • Gas tank-style water heater: Turn the dial to your preferred setting or between printed settings.
  • Electric tank-style water heater: Insert a flathead screwdriver tip into the slot and turn the post to make the adjustment.
  • Digital thermostat: Use the Up/Down arrows to make your adjustment.

After changing the water temperature setting, mark the new point without removing the original mark.

Step 5: Recheck the Water Temperature

Allow 12-24 hours for the water temperature in a tank-style water heater to adjust to the new setting. To speed up the process, run a significant amount of hot water (e.g., a dishwasher load or a couple of laundry loads) and let the water heater recover. Repeat steps 3 through 5 until the water reaches the desired temperature.

Once you've found the ideal temperature, remove any tape and use a permanent marker to mark the setting.

Health Warning and Energy Saving Tip

While 120°F is ideal for most households, there's a slight risk of legionellae bacteria in warm-but-not-hot water. The Department of Energy recommends a water heater temperature of 140°F for those with "a suppressed immune system or chronic respiratory disease". If you choose the 140°F setting, be aware of the burn risk, especially to children, the elderly, and pets. Caution guests in your home to prevent accidental burns.

As an energy-saving tip, when you plan to be away from home for more than a day or two, turn your water heater to the lowest setting. If it's an electric water heater, consider turning it off. Keep in mind you'll have a short wait for hot water after you get home and turn the water heater on or up.

Adjusting the water heater temperature is a simple DIY job using these easy steps. In a day or less, you'll have water that's safe for everyone to use and hot enough for laundry and bathing. Sharing this information with others is a great way to help them find the Goldilocks setting that's just right for all their household needs.


  1. U.S. Consumer Product Safety Commission. (n.d.). Tap Water Scalds. Retrieved from https://www.cpsc.gov/s3fs-public/5098-Tap-Water-Scalds.pdf
  2. U.S. Department of Energy. (n.d.). Savings Project: Lower Water Heating Temperature. Retrieved from https://www.energy.gov/energysaver/services/do-it-yourself-energy-savings-projects/savings-project-lower-water-heating
  3. U.S. Department of Energy. (n.d.). Water Heating. Retrieved from https://www.energy.gov/energysaver/heat-and-cool/water-heating

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