You might think, or might have been told, that washing your hands under hot water kills more germs. Time-saving, heat-bill-lowering cold water, however, works just as well at removing contamination, and saves your hands some stress.
Photo by aka Kath.
The New York Times reports that the US Food and Drug Administration has advocated for using "hot water comfortable enough for washing hands", as it purportedly removes oils from your hand skin that might harbour bacteria. But in 2005, a published study found that:
... In studies in which subjects had their hands contaminated, and then were instructed to wash and rinse with soap for 25 seconds using water with temperatures ranging from 40 degrees Fahrenheit [4 degrees Celsius]to 120 degrees [50 degrees Celsius] , the various temperatures had "no effect on transient or resident bacterial reduction."
Taking the time to thoroughly work soap into your hands and properly rinse them off are just as important with any temperature water. Still, if you've got a home with hot water that takes its time making it into your sink, consider saving yourself the time and water heater expenditure and wash with whatever feels good on your hands.