The temperature of water is not as important as the rubbing action of the hands with soap followed by rinsing with clean water. The water should be warm enough to allow the person to comfortably wash their hands long enough to sing the "Happy Birthday" song twice. A comfortable water temperature for most people is between 110-120 degrees. To prevent scalding, the water should never be hotter than 120 degrees. For more information, go to http://www.cdc.gov/handhygiene/.