Here is a great article I found while doing some research on the Internet. The article talks about the temperature of your water heater and what is the best degrees to keep it at.
The best temperature is 120°F. This protects your hot water heater from mineral buildup and corrosion and 140° water causes scalding.
Also the higher the temperature the more it costs you to heat the water. A water temperature of 140° can waste anywhere from $36 to $61 annually in standby and more than $400 in demand losses.
Here is the link to the article. Enjoy!