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A hand holding the adjustable thermostat knob of a residential water heater with both cold and hot water connections.

What is the Best Water Heater Temperature?

Finding the best water heater temperature is a great debate in many American homes. Set it too high and maximum temperatures will be scalding. Too low and you'll never enjoy the comfort of a hot shower. Not to mention, usually the higher your heater temperature is set, the more costly your energy bills will be.

Your heater accounts for about 18% of your home's energy bill, so it's important to both mitigate water use and ensure your temperature settings are in a good range to avoid exorbitantly high bills.

To help you decide the best water heater temperature for your home, the local HVAC service professionals at Aire Serv put together this helpful guide. Keep reading to discover answers to your pressing water heater temperature questions, plus tips from our pro team.

Which Setting is the Best Water Heater Temperature?

Typically, the standard water temperature for most machines is around 140 degrees F. However, the Department of Energy recommends turning it down to 120 degrees Fahrenheit to save energy. While you may be tempted to turn your water heater down further to further reduce energy usage, it's important to note that any setting below 120 degrees increases bacterial growth within the tank. The only exception to this is if you're going out of town for an extended period of time. In that case, it's safe to turn the thermostat to the lowest setting.

With that in mind, there are still a number of other variables to consider when selecting the best water heater temperature.

Your Dishwasher

Hot water makes for cleaner dishes. Not only is this true because it cuts through grease and oil, but also because it kills bacteria. If your dishwasher doesn't have a booster heater, then you should keep your thermostat at 140 degrees F for optimal cleaning. If you're not sure whether your dishwasher has this feature, check your owner's manual for more information.

Your Health

For most healthy people, bacterial growth inside a tank set to 120 degrees is a safe amount. However, there are a few instances where you may need to keep your machine at 140 degrees to be on the safe side. For instance, if you have a suppressed immune system or respiratory disease.

The Number of People in Your Home

Have you ever hopped in a shower only to discover there is no hot water left? This is a common problem in large households. Whether you have a big family or live with many roommates, cold showers can be frustrating—especially if you're always last in line. By keeping your tank at 140 degrees, you can ensure there is enough heat for everyone.

Whether You Have Children

Burns can be very serious, and infants, young children and elderly family members are all more sensitive to hotter temperatures. In fact, it only takes two seconds for a child to receive third-degree burns from water that is 150 degrees, and five seconds if it is 140 degrees. If you have small children or elderly parents living with you, be sure to turn the temperature down to 120 degrees.

Your Budget

Every 10 degrees you turn down a water tank thermometer, you save 3 to 5% on your energy bill. Whether you want to curb household expenses, are saving up for a big trip or would like to put that extra cash in a rainy day fund, lowering your water heater thermostat has numerous benefits. Not to mention, you save on energy consumption too—which is good for your wallet and eco-footprint.

Other ways to lower energy costs include:

  • Taking cold showers, which also has benefits for skin and hair.

  • Washing laundry in cold water, which also helps maintain color and fabric quality.

  • Limiting time spent showering.

  • Using an energy efficient shower head.

  • Washing dishes by hand occasionally.

  • Ensuring plumbing fixtures are not leaking or dripping.

How to Adjust My Hot Water Heater Temperature?

Whether you think your tank is too hot for your two-year-old, or you want to improve your dishwasher's performance, it's beneficial to turn it to your ideal temperature. But how do you adjust the temperature setting to begin with? Follow these steps:

Measure Its Current Temperature

To know how much to change your settings by, first you need to know what they're at. To get an accurate reading, turn the hot water at a faucet located furthest from the heater. Then, place a thermometer under the stream. The reading should give you a clear idea of how much to adjust the thermostat by to find the best water heater temperature for you.

Locate the Thermostat Dial

The location of your thermostat dial depends on the type of water heater you have. Gas heaters have dials near the bottom of the tank, whereas electric heaters have thermostats behind screw-on panels. If your electric model has an upper and lower heating element, there may be two dials.

Measure and Adjust Settings

Adjust the thermostat up or down slightly. Wait for a few hours; it takes some time for temperatures to change. Measure the temperature again by carefully inserting a thermometer into a running tap, and make adjustments as needed. Once it's hit your desired temperature, be sure to mark that final temperature on the dial. This way, you'll be able to modify future settings more easily.

Is it Bad to Turn My Thermostat All the Way Up?

Yes, it's very bad to turn your water heater all the way up. To do so will reduce its life, increase your electricity bill and could possibly cause scalding—particularly if you have young children or an elderly relative living in your home. If you feel tempted to turn the thermostat to max because you aren't getting enough hot water, then there is likely a problem with the machine—not the temperature setting.

Why Don't I Have Hot Water?

There are a few reasons why your machine may not be warming up properly. While it's best to call a professional to take a look at the problem, you can troubleshoot the issue yourself. Often these causes result in not enough hot water:

No Power

A faulty electric thermostat or faulty upper electric heating element can be why your taps won't warm up. The first step is to reset any tripped breakers and replace blown fuses. Then, check if power is being supplied to the thermostat. If it isn't working, the issue is internal and requires expert repair services.

Undersized Heater

If your machine is too small for your home, it won't be able to work efficiently—and may cause a range of other problems. Despite trying to provide enough hot water, it won't be able to keep up. This will cause it to break down and deteriorate more rapidly.

Crossed Hot/Cold Connection

Whether you were tinkering around with your plumbing or the heater wasn't installed properly to begin with, you may not be able to take warm showers because the hot/cold connection has been mixed up. Check for this by turning on a cold tap. If hot water comes out, the connections need to be swapped.

Broken Heating Element

A damaged heating element can't do its job. In this case, the part will need to be replaced by a qualified service professional. Often, too much sediment is to blame for a damaged element.

What Affects My Heater's Performance?

Did you adjust your water heater's temperature, but still aren't satisfied? Perhaps there is a problem impeding its ability to heat properly, or it could be that there is another problem with the machine's performance. What might seem like an unusually cold heater may be a sign there is a problem—and if said problem is left alone too long, it will inevitably get worse. A few common issues that impact the machine's performance—and may make it hard to find the best water heater temperature—include:


Like other fixtures in your home—such as your furnace or air conditioning unit—water heaters are all too often neglected. Often installed in basements or garages, it's easy to neglect proper water heater maintenance. Unfortunately, much like how your car's performance is hindered by irregular check-ups, the same happens to your heater.

These machines should be serviced annually. If too many years go by without proper maintenance, they can develop leaks and other issues detrimental to their performance. Not only might this cause improper heating, but it could also cause problems with water pressure.

Sediment Build-Up

Created when hard water is heated, sediment builds up at the bottom of a water heater's tank. This causes a few different problems. In gas models, it causes the tank's base to overheat and melts away the protective glass lining. Meanwhile, in electric models, sediment causes the lower elements to get burned and buried.

It's also worth mentioning that too much sediment build-up can void a commercial machine's warranty. However, with regular maintenance many of these issues can be avoided.

Internal Rust

An important part of water heater maintenance is the upkeep of the machine's anode. This part helps protect the tank from rust. However, as time passes the anode can deteriorate—resulting in internal rust. Too much rust can also cause leaks. Water softeners can actually cause anodes to deteriorate more rapidly too. Thus, regular maintenance is key to preventing this issue.

Corrosive Fumes

To ensure you have hot showers, your machine draws in air for combustion—creating the energy needed for supplying hot water. The quality of this air is very important. Bleach, fumes, ammonia and other acids near the machine are corrosive and can harm its performance. These fumes are incredibly damaging, especially in a confined space.

High Water Pressure

It's very important that you keep your pressure below 80 psi (pounds per square inch). Most households sit at about 60 psi. High pressure can take a serious toll on your heater. Be sure to check your gauge to see how high the pressure is. Too much pressure can damage the machine and your plumbing system. Should you notice the pressure is too high, then consider installing a reducing valve or expansion tank. An expansion tank will protect the pipes against damage from thermal expansion.

Improper Sizing

Similar to how an oversized or undersized HVAC system can be problematic, heaters that are the wrong size can cause many problems in your home. Considerations for what size you need depend largely on how big your home is, and how many people live in your home. Heaters that are too small will eventually break down because of constant expansion and contraction of the tank. Machines that are too big are inefficient.

Transient Current

If your house is not grounded properly, then it's possible this damaging condition may occur. A transient current—an excessive current or current from other sources—can reach the electric water heater, or it's piping, and cause corrosion over time. The best way to prevent this from happening is by connecting the ground wiring into the incoming and outgoing piping of the machine. However, this job should not be handled by an amateur. If you suspect any electrical issues with your heater, call an expert from your local Aire Serv immediately.


All appliances have a limited lifespan, after which they become inefficient. This is true of your heater as well. Usually, these appliances last up to 10-15 years, while a tankless water heater may live up to 20 years. Should your machine be nearing the end of its lifespan, then it's time for an upgrade. This will actually save you money—and headaches—down the road.

Need Help to Get the Best Water Heater Temperature?

Whether you need help to find the best water heater temperature for your home, or you need repair or replacement services from an HVAC company, trust the experts at Aire Serv for the job. With anytime service, upfront pricing and a satisfaction guarantee, we're the team you can trust. We'll help you save money, time and stress by performing comprehensive HVAC repair, maintenance and installation services.

To book an appointment, call your local Aire Serv location today.