Best Water Heater Temperature Setting & How to Adjust

It is awesome having hot water running through your pipe and always available when you need it, but it has to be just the right temperature. Not too hot and not too cold/lukewarm.

Is there a right temperature setting for a water heater though? Yes there is and adjusting your water heater to the right temperature is actually quite easy as I will explain further down in this post.


According to the Department of Energy, the best water heater temperature setting is 1200 F. At that temperature setting, the water is hot enough to clean/shower, kill bacteria, will not scald and is also energy efficient. Some people will however prefer a temperature setting of between 130-140 degrees.

A new water heater will most likely be factory-set at 1400 F. Water heater manufacturers are concerned more about their products (not your energy bills) and want you to turn on your faucets and feel hot water immediately after installing the heater. Lukewarm water is a vote of no confidence in their product.

While water at 1400 F is great for people who are immunocompromised and those with respiratory complications, it is too hot for young children and the elderly. If you don’t have kids and seniors in the house and don’t mind the temperature yourself, stick with it.

Although 1200 F is the ideal water heater temperature setting, 1300 F will also work just fine. It is not too hot to scald your skin but it will kill the pathogens in the water without increasing your energy consumption by a big margin. Some expert plumbers even recommend a 130-140 degrees temperature setting.

Why Adjust Your Water Heater Temperature?

Most people adjust their water heater temperature settings primarily to prevent scalds but there are also other things that you need to be concerned about. The following are the reasons why you should adjust your water heater temperature settings, either upwards or downwards.

1. To Kill Bacteria

When most of us hear about bacteria in water, the first thing that we think about is the risk of infesting the bacteria. That is however not the only worry in this case.

Sulfate bacteria are the ones responsible for the rotten eggs smell in hot water due to the formation of hydrogen peroxide gas. This is especially the case for people using water from a well.

It goes without saying that bacteria will thrive inside the water heater as long the water temperature is low.

When the water temperature in the water heater is too low, Legionella, which is the bacteria that causes Legionnaire’s disease may start growing. The Occupational Safety and Health Administration (OSHA) notes that scale and sediment build up in the water heater encourages these bacteria to thrive.

Adjusting your water heater to a higher setting (1400 F) and flushing out sediments from the water heater will help deal with this problem.

2. To Prevent Scalding


Hot water has the potential to scald, especially when you have children and the elderly in the house. At the same time, setting the water heater temperature too low will be uncomfortable for them and will also foster bacteria growth.

Most people have found the sweet spot in as far as water heater temperature is concerned to be 1200 F. With young kids, their skins are just way too sensitive while the old folks have low sensitivity and are slow to respond to excessively hot water.

If you are concerned by this risk but still wouldn’t want to create a conducive environment for bacteria to thrive in your water heater, consider installing faucets with ant-scald devices.

Faucets with anti-scald devices limits how far the faucet turns in the direction of the hot water supply. This are especially helpful when installing shower faucets. What’s good is that the anti-scald device can be adjusted to give you just the right water temperature.

3. To Save Energy Bills

The higher you adjust your water heater temperature settings the more you will pay in energy bills. This may not be a concern for some people, but if you like to keep track of every dollar this will be important to you.

The approximation is that for every 10 degrees your turn up you water heater temperature, your energy bill increases by about 5%. If for instance your energy bill is roughly $120, the bill will increase by about $6.

How to Determine your Water Heater Temperature

Most water heaters are not equipped with a temperature read out and is therefore not that easy to tell what the temperature of your hot water is. If you want to find out what it is, this is how you do it:

  • Turn off all your hot water faucets and appliances for at least 1 hour. This will give the water in the heater ample time to heat up. People with a tankless water heater should skip this step.
  • Open a hot water faucet and let the water run down the drain for 2 minutes to remove all the cold and lukewarm water in the supply pipes.
  • Fill a cup with water and insert a thermometer. Check the reading on the thermometer.
  • Adjust your thermometer accordingly and if need be repeat the above steps until you get your desired water temperature.

How to Adjust the Temperature of a Gas Water Heater


Natural gas water heater temperatures are just so easy to adjust. There is dial at the bottom of the heater that allows you to either increase or reduce the water temperature.

The only challenge is that there are no markings on the dial so you do not know exactly by how much you are increasing or reducing the temperature. Some dials will only have a warm, hot, and very hot setting.

In that case, you will need to look for a nice spot between the warm and the hot setting. This means you may need to adjust the dial a few times before getting the right water temperature.

If you see some letter (A, B and C) on the temperature adjustment dial, then the adjustment will be fast and more accurate. You may also see a small triangle symbol before the A.

Here is what each setting in the gas water heater temperature dial stands for:

  • Triangle: Ideal water temperature (115-120) degrees.
  • A: +10 degrees
  • B: +20 degrees
  • C: +30 degrees

If for instance you put the dial on the A, the temperature setting will be 120 + 10 degrees which is 130 degrees Fahrenheit. At C it will be 150 degrees Fahrenheit.

How to Adjust Water Temperature in an Electric Water Heater


Electric water heaters have 2 thermostats and 2 heating elements. The thermostats regulate the water temperature inside the water heater by turning the heating element on and off.

To adjust the water temperature in an electric water heater, you will first need to access the thermostats. The thermostats are concealed by cover plates that you will first need to remove.

This is how to adjust the water temperature in an electric water heater:

  • Start by turning off power to the water heater.
  • Use a screwdriver to remove screws from the upper and lower thermostat cover plates.
  • Remove the small piece of insulation covering the thermostat.
  • Adjust the temperature. You will see the water temperature adjustment screw and gauge. Use a flathead screwdriver to adjust the temperature to 120 degrees Fahrenheit or higher as you wish. The upper thermostat should have a slightly higher setting than the lower one.
  • Put back the insulation and cover plate and secure it back with the screws.
  • Turn the power to the water heater back on.

How to Adjust a Tankless Water Heater Temperature.

tankless water heater temperature setting

Adjusting the water temperature in a tankless water heater is quite easy. You only need to press the up or down arrow and select your preferred temperature setting.

Sometimes with tankless water heaters like the Rheem tankless water heater you may find that you are unable to increase the water temperature past the 120 degrees setting. They do this on purpose to prevent lawsuits in case you are badly scalded.

If you want to adjust the temperature past the 120 degrees setting, press and hold the up arrow until the temperature moves to 140 and starts to blink. While still holding the up arrow, press and release the down arrow.

When you do that, you can adjust the temperature easily, either up or down.

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