You don't need to risk scalding yourself in order to get clean hands. According to researchers, washing your hands in cold water is just as effective at reducing bacteria as washing your hands in hot water. That's based on a small study of 21 people described in the Journal of Food Protection. Over a six-month period, Rutgers University researchers covered participants' hands in harmless bacteria, then asked them to wash their hands 20 times each with water at around 60 degrees, 79 degrees, and 100 degrees Fahrenheit. They also experimented with the amount of soap used: either 0.5, 1, or 2 milliliters. No matter the amount of soap or the water temperature, the amount of bacteria removed when washing was the same, reports the BBC.
"As far as effectiveness, this study shows us that the temperature of the water used didn't matter," researcher Donald Schaffner says in a release. Currently, the FDA recommends restaurants use water at 100 degrees for hand-washing, but Schaffner says there should now be a policy change. "We are wasting energy to heat water to a level that is not necessary," he says. While the CDC notes individuals can use either warm or cold water, it also recommends washing hands vigorously for at least 20 seconds. The Rutgers study, however, found "washing for 10 seconds significantly removed bacteria from the hands," Schaffner says. More research is still needed to determine the best soap for removing bacteria, reports Food Safety. (This study found a six-step hand-washing technique is best.)