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What Temperature Should a Hot Water Heater Be Set at?

Writen by Ronald Brown

Fact checked by Natalie Bridges

what temperature should a hot water heater be set at

Did you know that the standard hot water heater temperature setting is often 140 degrees Fahrenheit? Generally, water heater manufacturers set this number by default. This temperature level will help prevent the prevalence of Legionella bacteria in your domestic water supply.

But what temperature should a hot water heater be set at? Professionals recommend keeping your heater temperature between 120 to 140 degrees Fahrenheit, as these temperature levels will kill microorganisms in your water.

In addition, the best water heater temperature depends on numerous factors that I will discuss later in this article.

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Hot Water Temperature Levels Recommended by Professionals

What temp should a water heater be set at? According to the Occupational Safety and Health Administration (OSHA), the minimum water temperature for larger residential systems is 140 degrees Fahrenheit.

On the flip side, smaller systems need at least 130 degrees Fahrenheit. This temperature will provide a faucet or tap water temperature of 120 degrees Fahrenheit, the ideal temperature for domestic hot water.

120 degrees is the maximum safe hot water temperature approved by the Center for Disease Control and Prevention (CDC) and US Environmental Protection Agency (EPA). A hot water temp of 120 degrees Fahrenheit is adequately hot to keep diseases at bay while allowing steamy hot showers. It will also reduce overall energy and power consumption.

While the maximum temperature for most water heaters is 150 degrees Fahrenheit, The CPSC (Consumer Product Safety Commission) also urges homeowners to adjust the thermostat to 120 degrees Fahrenheit to avoid scalding.

When it comes to hot water, children and older adults are especially vulnerable because thinner skin burns quickly. Furthermore, most kids will suffer from a 3rd-degree burn after a two-second exposure to 150-degree hot water. Similarly, a child can be scalded in less than 4 seconds at 131 degrees Fahrenheit.

As a result, children should always be supervised to prevent accidental water burns as they may play with the faucet temperature settings.

Most scalding burns among children are accidents, which is why parents are tempted to turn down the water heater temperature. However, anything lower than 120℉ will not give you an extra layer of protection against the possible proliferation of Legionella and other bacteria in your home water.

Although you can adjust the water heater to your preference, it is crucial to be mindful of your usage habits to protect your family from the negative impacts of temperature-setting mismanagement.

Factors That Affect Hot Water Heater Setting


Various factors contribute to the way we set up the temperature of our water heater. These elements will help you determine the ideal heat level:

1. Households With Elderly People and Children

As mentioned earlier, older adults and younger children have thinner skin and therefore face a scalding risk. Children as young as age 4 are reportedly hospitalized for burn-related injuries: scald burn and contact burn.

Meanwhile, stories about elderly or vulnerable people suffering from burn injuries or infections are rare. But we must still check if the water heater temp is at no more than 120 degrees Fahrenheit as a routine precaution.

There’s one exception to this rule, though. According to the Department Of Energy, if you have an immunocompromised member in the family, you may consider adjusting your unit to 140 degrees Fahrenheit.

2. Household Size

If you’re living alone, lower water demand is expected. Therefore, most single occupants would probably use a decreased temperature to conserve energy. Lowering the water heater to 120 degrees Fahrenheit will help you save water heating costs by up to 10%.

On average, a person can use 20-35 gallons per day in a residential house/flat. But a large household may opt for a higher hot water temperature due to higher hot water demand.

3. Pipe Size

How does the residential pipeline system affect your family’s hot water use? The smaller the internal diameter of the pipe, the lower the flow rate and pressure. For instance, a small bore piping system will require plenty of time for hot water to reach your faucets. Thus, heat will dissipate along the way.

If you have a larger house/property, you should consider installing a hot water recirculating system so that it would not take long to deliver hot water to your plumbing system. It also means that you no longer have to use a high temperature all the time, thereby saving a substantial amount of energy expenditure.

4. Non-Preheat Dishwasher

Most modern dishwashers today feature a pre-heating technology that raises the temperature of the incoming water. However, if your dishwasher does not preheat water, setting up the water heater to 140 degrees Fahrenheit will bring out the desired sanitizing temperature.

5. Ambient Outdoor Temperature

The ambient weather conditions massively affect what temperature level we should set our water heater to. Your hot water output may be contingent on the fickle weather outside.

For instance, the winter seasons will make the water coming to your pipes colder. Your heater will need to work harder as a consequence.

5 Quick and Easy Energy-saving Tips for Water Heater


1. Lower The Temperature On The Thermostat

According to the report of the Department Of Energy, we can yield at least 12 to 30 dollars of savings annually for every 10 degrees that we turn the temperature down.

2. Reduce Hot Water Usage & Insulate Water Tank

It is efficient to turn off the water heater for tasks that don’t require warm water like teeth brushing.

Also, lack of insulation can lead to more power being used. If you have an uninsulated tank, the water heater will cool more easily. In this case, it will take a long time to convert the incoming cold water into hot water, especially if the weather is abnormally cold.

3. Insulate The Water Heater Pipes

In addition to the tank, you must insulate the hot water pipes as it helps to reduce standby heat losses and prevents your tank from bursting, which is triggered by the freezing weather. This additional safeguard will also lengthen the lifespan of a water heater as you don’t need to turn it on frequently.

4. Inspect And Repair Leaky Valves

A leak is a classic water heater problem that most homeowners encounter. Most of the time, the leakage is caused by high water pressure. You should not take this issue lightly, as it can damage the water heater and waste over 90 gallons of water per day.

5. Drain Sediment From The Tank

Sediment buildups settle at the bottom of the tank and increase the heater’s power consumption, which is why the tank needs to be drained once every six months. You can check out this guide to understand clearly about how to drain a water heater.


‘What Temperature Should A Hot Water Heater Be Set At?’ is a common question among homeowners. I hope you’ve gained a deeper understanding of how you can properly regulate the temperature of your own water heater.

Knowing when to raise the heat of your thermostat will reduce the potential for scalding and microbial contamination. Do you have any questions about your hot water system? Feel free to write them in the comment box below.

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