For effective hand hygiene, water temperature matters less than time, according to a study published in the Journal of Food Protection.
Researchers contaminated the hands of volunteers with high levels of a harmless bacteria several times over six months. The participants were then asked to wash their hands in 60-degree, 79-degree or 100-degree water.
The team found cold water to be as effective as hot in eradicating harmful bacteria and other germs. What’s more important, they researchers said, is that people scrub their hands with soap for at least 10 seconds. The amount of soap the people used didn’t affect the findings.
“Understanding what behaviors and human factors most influence hand washing may help researchers find techniques to optimize the effectiveness of hand washing,” the researchers write.