The temperature you set for your water heater can affect your comfort and your wallet as well as your energy efficiency and safety. The best temperature setting is one that balances all those things, letting you enjoy your morning shower while reducing risks as much as possible.
Let’s take a deep dive into the warm waters of optimal temperature settings.
The Goldilocks Guide to Getting Your Water Heater Temperature Just Right
According to the U.S. Department of Energy, the ideal water heater temperature is 120 F. This setting gives you nice, warm showers and sanitary dishwashing and laundry without being scalding hot. (Link)
According to the U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA), on the other hand, the ideal water heater temperature is 140 F. This slightly warmer setting uses more energy but gives you a bit of extra protection against bacteria for people with compromised immune systems. However, it comes with a higher risk of scalding, especially for people with sensitive skin. (Link)
Setting your water heater below 120 F is generally not recommended. Using lukewarm water settings can increase the risk of bacterial growth and may not provide enough heat for your household needs.
If you have kids at home, a hot water temperature of 120 F is cool enough to minimize their risk of accidentally burning their delicate skin. Thermal injury studies indicate that it takes around five minutes of direct exposure to 120-degree water to cause a third-degree burn, which is usually more than enough time to avoid accidents. (Link)
There are situations where you might want to crank up the heat a bit. If you have a dishwasher that doesn’t preheat water, you might need to keep your heater at 130 F or higher to properly sanitize your dishes. If you have a large household with high water demand, if you just prefer hotter showers, or if someone in your home has a compromised immune system, you might want to set your water heater as high as 140 F.
Even at these slightly higher temperatures, though, your risk of scalding increases quite a bit. It also means your water heater will use more energy, which could bump up your utility bills.
What Happens If I Set My Water Heater Too Low?
If you set your water heater below 120 F, you’ll save on energy costs, but you’ll also enter a lukewarm zone that comes with a few concerns:
- Temperatures below 120 F create a cozy environment for bacteria and other harmful microorganisms to thrive. These uninvited guests can cause some nasty illnesses, especially for people with weaker immune systems. For example, if you inhale the Legionella bacteria through water vapor, it can give you a serious lung infection. (Link)
- Water that isn’t hot enough may not effectively remove grease and bacteria from your dishes or clothes. This means you’ll need to run your dishwasher or washing machine on longer cycles or at higher temperatures, potentially negating your energy savings.
- You might run out of hot water quickly, especially if multiple people in your household take showers around the same time or if you need to run your dishwasher and washing machine simultaneously.
- Insufficient heat can prevent surfaces from drying properly, letting moisture linger and creating a breeding ground for mold and mildew. This can lead to moldy shower curtains and walls, mildew on bathroom surfaces and fixtures, and bacterial growth and mineral deposits in your faucets and sinks.
What Happens If I Set My Water Heater Too High?
One of the most immediate dangers of setting your water heater too high is the increased risk of scalding. According to the American Burn Association, 140-degree water can give you a third-degree burn in seconds, so you’ll need to be extra careful. (Link)
Besides burns, the higher you set your water heater, the more energy it needs to maintain that temperature, which will noticeably increase your energy bills and carbon footprint. Your constantly grinding water heater will also experience more wear and tear, which can shorten its lifespan.
Water Heater Temperature Tips
Here are a few tips to stay safe and efficient without sacrificing comfort:
- If possible, try to put your water heater in a warmer area of your home so it doesn’t have to fight so hard against cold ambient temperatures.
- Insulating your water heater tank and your first few feet of hot water pipes can cut down on heat loss and give you a more consistent water temperature.
- Flushing the tank once or twice a year removes sediment buildup that can make your water heater less efficient.
- Installing a timer or smart controller can help you make sure it only heats water when needed.
- If your water heater is more than 10-15 years old, it might be time to upgrade to a newer, more energy-efficient model with better insulation and more precise temperature controls.
How to Check and Adjust Your Water Heater Temperature
Many water heaters use temperature controls that go from Warm to Hot to Very Hot instead of measuring actual degrees. To test the real temperature of your hot water, you can use a cup and a kitchen or digital thermometer that can read temperatures up to at least 160 F:
- Test the water in your heater’s closest faucet as well as its farthest to see how much the water cools off when it travels through your pipes.
- Run your hot water tap at full capacity for two or three minutes to get your heater’s full effect.
- Fill a large mug with hot water.
- Immediately place your thermometer in the mug, fully submerging the sensor.
- Wait 30 seconds for the reading to stabilize, and then check the result.
- If the temperature is too high or too low, adjust your heater’s thermostat, and repeat the test.
Adjusting Your Thermostat
Adjusting your thermostat will depend on what kind of water heater you have. If you use a gas water heater:
- Find the temperature control dial, usually near the bottom on the front or side of your water heater.
- If your temperature control goes from Low to High or Warm to Hot, the lowest settings usually correspond to 80 or 90 F, the middle usually meets 120 F, and the highest setting is generally around 160 F. You can verify this with the above temperature test.
- If your water temperature is too low, turn the dial clockwise a bit. If it’s too high, turn the dial counterclockwise.
- Wait about an hour for the heater to adjust the temperature, and then test it again.
If you use an electric water heater:
- Start by turning off your water heater’s corresponding circuit breaker to avoid electric shock.
- Electric water heaters often have two thermostats for upper and lower heating elements. These may be hidden behind access panels and insulation. Unscrew the panels and peel back the insulation to uncover the controls.
- You may only be able to adjust the control dial with a flathead screwdriver. Remember, clockwise raises the temperature, and counterclockwise lowers it. Leave both thermostats at the same setting.
- Wait for your heater to adjust, and then test your new setting before replacing your access panels and insulation.
Conclusion: Water You Waiting For?
To find the perfect water temperature that benefits your family and your wallet, you’ll need to think about how the recommended temperature range matches your household’s specific needs. Adjusting your thermostat can take some time and effort, but it’s worth the extra peace of mind and lower energy bills.
If you’re unsure about your water heater’s temperature setting or you notice inconsistent temperatures or other issues, it may be time to call in a professional plumber. The experts at Benjamin Franklin Plumbing can give you personalized advice and top-notch service with a smile to make sure your water heater operates safely and efficiently.