How and Why to Change the Temperature on Your Water Heater
You probably don’t think much about your water heater, unless you take a shower and run out of hot water. Or worse, if the water is too hot and causes scalding. You can adjust the temperature of your water heater, but should you?
While you may think water heaters have a standard recommended temperature, it’s not that simple. The Department of Energy recommends setting your water heater to 120°F (49°C) to save money on hot water, whereas the Consumer Product Safety Commission recommends the same temperature in order to prevent scalding. And while many manufacturers factory-set their water heaters to this temperature, OSHA recommends setting the temperature higher to help prevent the growth of harmful bacteria.
Hot Water Kills Harmful Pathogens
Legionella, the bacteria that causes Legionnaires' disease can become a health concern when it grows in home water systems. “Water heaters maintained below 60°C (140°F) and that contain scale and sediment may foster Legionella growth,” says OSHA. Thankfully, most heathy people exposed to Legionella do not get sick, says the CDC. But before you decide to turn up the temperature dial of your water heater, read on.
Hot Water Can Scald
Hot tap water is a major cause of burn injuries. Scald burns are a real concern, especially if you have children under 5 or adults over 65 living in your home. These two age groups are at highest risk for scalds: Young children, because their skin is thinner, and the elderly, because they can be less sensitive to temperature and may be slower to respond to scalding water. However, even a healthy adult can get a first-degree burn in 2 seconds when tap water is 140°F.
Minimize Risk with Anti-Scald Devices
So how do you negotiate the two opposing risks: growth of bacteria and risk of scalds? Newer homes typically have anti-scald devices, but if you live in an older home, you can add anti-scald guards and devices to showerheads and tub spouts to help avoid dangerously hot water. Talk to a plumber about installing a thermostatic mixing valve (also called tempering or anti-scald valve) that limits the max temperature coming out of your water heater.
What is My Water Heater Temperature?
On most tank water heaters, and some tankless, you won’t be able to tell the temperature just by looking at the temperature dial, as most are simply marked from “Low” to “Hot” (or “Very Hot”). If you have your water heater manual, the default temperature will be listed there. If not, simply search the internet for the brand and type of water heater and its “default temperature.”
However, the water heater’s default temperature isn’t the temperature that is coming out of your taps. To be safe, check your tap water temperature.
How to Check Your Tap Water Temperature
- Do not use your hot water for at least two hours before testing. If you have a tankless water heater, you can skip this step.
- Let hot water run for at least three minutes. Test the temperature with a candy, meat, or water thermometer.
- Adjust the temperature on your water heater thermostat. Repeat steps 2 and 3 until you reach the desired temperature.
- Wait a full day to allow the water temperature to change, then re-test again. You can skip this step for a tankless water heater.
Pro Tip: When you find the temperature you want, mark the temperature dial on your water heater with a permanent marker.