You can save from 3%-5% on your energy bill for every 10ºF that you lower the temperature of your water heater. A lower hot water temperature will also prevent scalding when members of your household use hot water.
There's no need to heat your water when you're not there to use it. For even more savings, turn down the temperature of your water heater or turn it off completely if you'll be out of town for three or more days. However, be sure to read the owner's manual for your water heater before making any changes to it.
1. Consult the owner's manual for your water heater for instructions on operating the thermostat and where to find the thermostat dial.
2. Before making any changes to your water heater's temperature, shut off the electricity to the water heater using your home's electrical panel.
3. Test the temperature of the water that comes out of your hot water faucet. Turn on the faucet that's farthest away from your water heater and run the water until it's completely hot. Put a cooking thermometer into a tall glass and fill the glass with hot tap water to test its temperature. It should be approximately 120ºF.
4. If you have an electric water heater, you will likely have two thermostats: One near the top of the tank and one near the bottom. You will need to adjust both of them to the same temperature. If you have a gas storage water heater, the thermostat dial will likely be located on the gas valve near the bottom of the tank.
5. Using a screwdriver, set the temperature of your water heater to 120ºF-130ºF, depending on the temperature of the water that came out of your hot-water faucet.
Differences between water in the tank and faucet. The temperature of the water in your water heater may differ from the temperature of hot water that comes out of your faucet. It's important to test the temperature of the tap water using the hot-water faucet that's farthest away from the water heater.
Tap water should be 120 degrees. Ideally, the water that comes out of your hot water faucet should be 120 degrees.
Tank water should be 120-130 degrees. To prevent the growth of bacteria, the temperature of your hot water tank should be at least 120-130 degrees.