Whether you are a fan of extra hot baths or cold showers, you can’t underestimate the importance of getting your water heater to that perfect temperature.
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The ideal temperature certainly does depend on your preferences. However, experts recommend keeping the setting above 120 F to prevent bacterial growth; increase the temperature to 140 F, if there is an immunosuppressed person living in the house and if you have a dishwasher that doesn’t pre-heat.
What’s The Best Water Heater Temperature Setting?
You might be thinking that the most important reason why the water heater should be able to bring the H2O to a high temperature is so that you can have a nice hot shower or bath.
But that’s not exactly how it is.
The main mission of your water heater is to get rid of the majority of bacteria by raising the temperature of your water.
The U.S. Consumer Product Safety Commission encourages all users to keep the temperature setting on their water heaters at 120 F. Such temperature doesn’t cause scalding and helps conserve energy and save money.
At the same time, 120 F is the minimum temperature that helps prevent the growth of various bacteria inside your water heater.
However, even this temperature can cause third-degree burns, if the skin is exposed to it for over 5 minutes.
A lot of water heaters have a default setting of 140 F, but do bear in mind that only a 6-second exposure to such hot water can lead to severe burns.
Here are some general recommendations:
| Temperature Setting | When You Should Stick to It |
| 120 F | If there are young children or elderly people in your house, who can easily get burnt by the water If you live alone and don’t have a high demand for hot water |
| 140 F | If there is an immunosuppressed person living in the house If you have a dishwasher that does not pre-heat If there are several people living in the household and the demand for hot water is high |
Tip: water tank boosters can keep your tank at 140 F to kill bacteria, but then get the hot water mixed with cold H2O, so that the water delivered at the tap is not dangerously hot.
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Read: No Hot Water In The House? Here’s Why
Tankless Water Heater Temperature
Whether your system has a tank or is tankless, gets heated up by gas or electricity – that doesn’t really matter.
The ideal temperature of the water heater does not depend on the type of unit that you have.
Read: How Much Cost Is To Move Water Heater To Garage?
What Is the Maximum Temperature for a Hot Water Heater?
The safety recommendation against scalding is 120 F. That is also the minimum temperature that gets a lot of pathogens killed.
Water heaters come with a thermostat and some of those allow you to set the temperature to up to 180 F. But that does not mean that you should do that.
To find your perfect temperature, simply switch the thermostat to 120 F and then start slowly increasing the temperature to find the one that works best for you.
By the way, if you set the thermostat to 140 F, it does not necessarily mean that the water coming from our tap is going to be 140 degrees. If the water needs to travel a long way to reach your shower and if some of the pipes are located outside and have become cold, then the temperature can get dropped by as much as 10 F along the way.
Is 130 Degrees Too Hot for Water Heater?
A burn will occur if you get exposed to 130-degree water for over 30 seconds.
Is 150 Degrees Too Hot for Water Heater?
The majority of adults are going to suffer from third-degree burns if they get exposed to 150-degree water for only 3 seconds.
Set Water Heater Temperature
Different manufacturers have various default settings on their water heaters. Some go for 120 F, while others – for 140 F.
However, that does not mean that such a setting would be perfect for you. So, take your time to get the temperature just right.
Electric Water Heater Temperature Setting
Most electric water heaters have a thermostat. You’ll find it behind an insulated access panel.
Some electric units have 2 thermostats – at the top and at the bottom of the tank.
Before making any changes to the temperature setting, you should test the water that is coming out of your tap.
Turn on the water and wait for it to get hot. After that, hold a thermometer under the water and take note of the temperature.
Tip: if you have a tankless water heater, you can simply use a digital control panel to adjust the temperature.
For the electric heaters that have a thermostat behind an access panel:
- Turn the power to the water heater off.
- Locate the access panel and use a screwdriver to remove it.
- There, you are going to see insulation of some sort. Peel it back.
- The thermostat can be adjusted with a flathead screwdriver. If your unit has two thermostats, make sure to adjust both the same amount (the top one, however, has to stay a few degrees higher than the other one).
- Put the insulation and the access panel back in place.
- Turn on the power and test the water’s temperature.
Hot Water Heater Temperature Setting A B C
Water heaters don’t always have thermostats with actual numbers. Some units have an A B C knob.
Every letter has a different temperature setting. In a lot of cases, A is 130 degrees, B – 140 F, and C – 150 F.
The other settings might include ‘hot’ and ‘very hot’. These stand for 120 F and 160 F respectively.
To change the temperature, simply turn the knob to the preferred setting.
If your water heater doesn’t have a ‘hot’ setting and A is the first one, then the chances are high that A stands for 120 F.
Rheem Water Heater Temperature Settings
A Rheem water heater comes preset at 120 F, but you can always adjust the temperature to anywhere from 90 to 150 degrees.
To change the temperature, follow the instructions that we have given above for electric water heaters.
When turning off the breaker to your Rheem unit, make sure to turn off all the 30-amp double-pole breakers, if they have not been labeled.
Read: Rheem Water Heater Troubleshooting
How to Lower Hot Water Heater Temperature?
To lower the temperature of a gas water heater, you should find the control dial (it’s located somewhere on the outside of the device).
Some dials have numbers, while others might not. Here’s what you can do, in such a case:
- Run the hot water at the faucet closest to the heater for at least 3 minutes.
- Use a thermometer to measure the temperature of the water coming from the tap.
- To lower the temperature, turn the knob down (mark the angle at which the knob was turned before).
- Wait 24 hours before testing the water’s temperature again.
- Adjust until you get to your preferred setting, marking the changes and writing the temperature down every time.
Read: Does HVAC Include Water Heater?
Risks Of Too High or Too Low Water Heater Temperature
A water heater is the 2nd highest source of energy usage in your house.
You might be tempted to lower the temperature just a bit. After all, a 10-degree reduction in temperature will help you save up to 5% of the energy associated with water heating.
The main problem with the temperature being set too low is the fact that various bacteria will be able to survive. Legionella, for example, gets killed only at 122 F.
So, instead of lowering the temperature, you might want to consider simply using less water on a daily basis. If the set temperature on your water heater is too high, your skin might get burnt. It will also lead to high energy bills and a decrease in the unit’s lifespan as there will be much more mineral buildup.