There are two opposing risks to weigh before choosing a temperature setting. Set it too low and you risk Legionella, the bacteria that causes Legionnaires' disease; set it too high and you risk scalding. A true dilemma.
Legionnaires' disease is a serious illness with high death rates (up to 12%). The groups most at risk are the elderly, the immunocompromised, and people with chronic respiratory illness. So while we want to protect against scalding, we generally advise setting the temperature high enough to prevent bacterial growth.
How to Check Your Water Temperature
Before changing anything, find out the current temperature. You can glance at the dial, but if the water feels colder than the dial suggests, measure it manually. You'll need a cup and a cooking thermometer. Let the hot water sit undisturbed for at least an hour (don't open any hot faucets). Then open the faucet nearest the heater, let it run a minute to heat the pipes, fill the cup, and check the temperature.
The Best Temperature Setting
Water heaters ship with a default of 140°F. Many people leave it there and are fine, but the right setting depends on your situation:
- Energy savings: The Department of Energy recommends 120°F to save energy.
- Bacterial growth: 120°F can allow bacteria; if you want to be safe, raise it toward 140°F.
- Children: Water at 150°F can cause third-degree burns in about two seconds. With kids in the house, keep it around 130°F.
- Big family or big house: More people or longer pipe runs may call for 140°F so everyone gets a warm bath and distant faucets stay hot.
Our recommendation is 130°F — hot enough to discourage bacteria, safe enough for children, sufficient for big families, and still energy-conscious. If you want a range, 120–140°F is fine.
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Its external digital display lets you dial in an exact temperature — ideal for balancing scald safety against bacteria control.
Final Editorial Verdict
How to Adjust the Temperature
The method depends on your heater type. Many gas heaters are simple: just rotate the knob to your desired setting. Some newer gas and electric units are trickier.
Understanding the Labels — Hot, A, B, C, Very Hot
If you're lucky, the dial shows degrees (80, 90, 120°F). Otherwise it uses letters or words. Here's the translation, regardless of heater type:
- Hot (or a triangle) = 120°
- A = 130°
- B = 140°
- C = 150°
- Very Hot = 160°
- Low / Warm = 80–90°
- Vacation / Pilot = water is not heated but the pilot stays lit
Changing Gas or Electric Settings
- Turn off the electricity at the circuit breaker.
- Remove the access panel(s) — they may snap off or need a screwdriver.
- Peel back the insulation to find the thermostat.
- Rotate the thermostat with a screwdriver to your desired setting.
- If there are two thermostats, set the top one slightly higher than the bottom.
- Replace the insulation and access panel.
For gas heaters, you may need to relight the pilot light afterward. Once you've changed the setting, it takes a few hours for the water to reach the new temperature — wait about three hours, then check with the thermometer and adjust again if needed.
Conclusion
Balance safety and efficiency: 130°F is the sweet spot for most homes, with 120–140°F an acceptable range. Check your current temperature, adjust carefully, and give the tank a few hours to catch up before re-testing.