A common misconception among homeowners is that raising the thermostat setting on the water heater increases the amount of hot water in the tank. The only thing that happens is the water is often heated to an unsafe temperature level. In this picture, the hot water level in this house is at an unsafe 140 degrees which is hot enough to burn and scald human skin. Water heater thermostats should be adjusted to produce hot water not in excess of 120 degrees. The nifty device used to measure the water temperature in this picture is a Raytek MiniTemp Laser thermometer.