Ok, ok, this tip is as old as the hills, but it stands the test of time. Set the water heater to 120°F. There is just no need for it to be any higher, and if you have little ones in the home, this can protect from serious accidental burns. How do you actually turn the temperature down? Check out this article from The Natural Handyman, he’s got some good info here on resetting the gauges while keeping the water hot enough for things like dishwashers and multiple showers.