What Is the Best Water Heater Temperature? 

Updated
Categories Water Heating
Here’s why it’s important to know the best temperature for your water heater. 

Do you like scalding hot showers? Perhaps you prefer lukewarm water? When thinking about the ideal temperature of the water in your heater, it would seem a personal matter of choice. But actually, there’s a lot more to consider.

There are safety reasons we should be aware of, as well as health considerations. And there is also the issue of saving energy and water. Wasting our planet’s resources is no longer acceptable.

Today, we cannot ignore how precious water and energy are. We must realize that having easy access to water means we should be grateful. Half of the planet is not so lucky, so it is our duty to act responsibly.


Safety and Health Considerations

When we buy a water heater and install it in our home, the temperature is set to 140 degrees Fahrenheit or 60 degrees Centigrade. This is the manufacturer’s default setting for temperature. If we take a shower running only the hot water at this temperature, we will get scalded or seriously burned.

Children and the elderly are particularly at risk of critical burns. Children because their skin is more delicate. Elders because their reflexes may be a little slower in realizing the water is too hot and backing away. So, why is the temperature set so high?

There are two main reasons.

1. Preventing Bacterial Growth

We all know that bacteria grow better in lukewarm, stagnant water. There are exceptions, of course: some bacteria thrive in extremely cold or hot temperatures. But the “danger zone” is between 41 degrees and 135 degrees Fahrenheit or 5 to 57 degrees Centigrade (1).

A setting of 140 degrees Fahrenheit or 60 degrees Centigrade is slightly higher than the danger zone limit. This is why it is a safer temperature for preventing the growth of bacteria.

Still, experts agree that water heater temperature is actually safe for the majority of people when it’s set at 120 degrees Fahrenheit or 50 degrees Centigrade (2).

The exception to this is for those who have a suppressed immune system or chronic respiratory disease. If this is the case, it’s better to stick with the default of 140 degrees Fahrenheit or 60 degrees Centigrade.

Most modern water heaters do have the tank temperature set at the default. However, they typically have an anti-scald device that delivers it to the faucet at 120 degrees Fahrenheit or 50 degrees Centigrade (3).

In water heaters, the concern is specifically linked to legionella bacteria. These organisms tend to accumulate on the bottom of the water heater and can cause a form of pneumonia. Usually, the bacteria is transmitted by inhaling contaminated water droplets when we shower or bathe.

2. Marketing Benefits

When manufacturers sell you a water heater, they are primarily concerned with client satisfaction. They’re not too worried about energy saving or water conservation. They want us to turn the hot water faucet and feel happy about our purchase.

If the water is lukewarm, most of us will think that the water heater is not doing its job properly. On the other hand, think of opening the tap and the water is instantly scalding hot. We’re more likely to think we’ve got a good deal.

All that is needed to get scalding water is raising the temperature setting. This doesn’t reflect on the overall quality of the water heater. But there’s a lot of psychology behind sales.

We need to think, and not be deceived, though. The temperature of the water is just a matter of setting. Whereas, choosing an energy-efficient water heater will benefit us in the long run.

Water Temperature and Saving Energy

One aspect of water heater temperature is sometimes overlooked. Setting the right temperature can save energy, regardless of what type of water heater you install. It’s a bonus that will also save you money in the long run.

1. Set the Temperature at 120 F or 50° C

We’ve seen that unless you have a suppressed immune system or chronic respiratory problems, 120 degrees Fahrenheit or 50 degrees Centigrade is warm enough. You don’t need to set the thermostat of your water heater any higher. This temperature will also help save energy.

How much can you save? Each time you turn down the temperature by 10 degrees Fahrenheit, you save 3 to 5 percent on your energy cost. Therefore, lowering the temperature from 140 degrees to 120 degrees Fahrenheit or 60 degrees Centigrade to 50 degrees Centigrade will save you between 6 to 10 percent on your bill (4).

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2. Choose an Energy Efficient Appliance

Not all water heaters are created equal. So, when you buy one, don’t look for the cheapest model. Purchasing it may save you a few dollars, but over time they will be lost on your energy consumption.

Instead, look out for the energy factor as shown on the model. Experts recommend Energy Star models.

Energy factors between 0.67 and 0.70 are the most energy efficient. Also, the smaller the water heater, the more efficient it will be as there will be less heat loss (5).

If you can, choose a heater with a large range of temperature control. You need one that will allow you to change the temperature precisely, one degree at a time. Then you can be confident that you will be able to get the ideal setting for any eventuality.

3. Use Cold Water

We’re not suggesting you should take cold showers, but sometimes cold water will do. For example, for laundry loads, or to wash your hands. Just use antibacterial soap. Every little gesture counts.

How to Adjust the Water Heater Temperature

There are five main types of water heaters available on the market. Let’s look at each in detail in terms of saving on your energy bill. We’ll also see how to change the water temperature for each kind.

Conventional Storage Tank Water Heater

These are the traditional water heaters that heat as much water as the tank can hold. They are insulated, so the water stays warm until needed.

If you need more hot water than the capacity of the tank, you’ll have to wait. It may take an hour or two for it to heat up again.

These are the cheapest and most common water heaters. But they are not the most energy efficient unless you install a timer. This way, the heater will turn off when the water reaches the right temperature.

To adjust the water temperature, all you need is a flat screwdriver.

  1. Turn off the water heater.
  2. Remove top and bottom covers.
  3. Use a flat screwdriver to adjust the thermostat.
  4. Replace covers.
  5. Turn on the power again.

Tankless Water Heater

Tankless water heaters do not have a tank. They use super-heated coils that heat water almost instantly, as required. These heaters come in different sizes, depending on how much hot water you need.

They work best using natural gas. So, if you choose an electric one it may actually increase your energy bill.

To adjust the water temperature, simply use the LED panel provided.

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Heat Pump Water Heaters

This model uses the heat in the air and ground to raise the water temperature. It uses electricity only to move the heat and not to generate it. It also has a tank which needs to be cleaned regularly.

Heat pump water heaters can help save up to 60 percent on your energy bill. But they are quite expensive to buy and need a lot of space for installation. The pump is on the top, and it may need up to 8 feet of vertical clearance (source).

Solar Powered Water Heaters

As the name suggests, these water heaters use the power of the sun. They will need solar panels mounted on the roof. These will work great on sunny days and in warm climates. On cloudy or rainy days, however, you’ll need a back-up water heater.

In terms of energy efficiency, these models are amazing. But unless you can get a Government grant, installing solar panels is very costly. It also may take several years to see a return on your investment (6).

Solar powered water heaters have a control panel that you can easily adjust to the ideal temperature.

Condensing Water Heaters

These use exhaust gas — the byproduct of gas used for other purposes — to heat water (7). So, if your household runs on natural gas, a condensing water heater may be the best choice for you. Note though, that it usually requires a big tank, so it’s ideal for large households.

You can easily set the perfect temperature from the control panel.

Technology

Nowadays, technology comes to our aid in almost any situation. You can buy and install a water heater controller kit. This will allow you to control your water heater’s temperature with your smartphone or tablet.

All you need is a working internet connection. You’ll be able to control your water heater from anywhere. Let’s say you’ve left on vacation and forgot to turn it off. Not to worry!

With this device, you can turn the heating off it to save energy, even from the other side of the world. Pretty cool! Just remember to turn it back on before arriving home.


Wrapping It Up

We’ve seen that in an ideal situation, the best temperature to set your water heater is 120 degrees Fahrenheit or 50 degrees Centigrade. This helps save energy and minimize the risk of burns. However, it is warm enough to kill bacteria, but not so hot that you’ll get accidentally scalded.

We’ve gone over the many different models of water heaters. Most modern ones have a simple way of adjusting them to obtain the best water heater temperature for your individual needs. You can even install a device to control the operation and temperature with your smartphone or tablet.

Do you have any questions or tips you’d like to share from personal experience? We’d love to hear from you — leave us a comment down below.

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.
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