Why It Might Be OK for You to Wash Your Hands With Cold Water After All

It's an adage you've heard practically from day one of your life: Wash your hands with hot water instead of cold.

Yet it seems the temperature of the water doesn't actually matter when it comes to getting rid of dangerous bacteria, according to a new Rutgers University-New Brunswick study published in the Journal of Food Protection's June edition. GOJO Industries provided the soap and collaborated on the study , though the company did not fund it.

The researchers placed high levels of harmless bacteria on the hands of 20 participants several times over the course of six months and had them wash their hands in either 60-degree, 79-degree or 100-degree water temperatures. They were instructed to use 0.5 milliliter, 1 milliliter or 2 milliliter volumes of soap.

Researchers found the temperature of the water didn't change how much bacteria was removed. "Also we learned even washing for 10 seconds significantly removed bacteria from the hands," study author Donald Schaffner of Rutgers said in a statement.

Current Food and Drug Administration guidelines for states suggest plumbing systems at food establishments and restaurants provide hand washing water at 100 degrees Fahrenheit. These guidelines, issued every four years, are considered mandatory by many states.

And what's more, using cold water is a bigger energy-saver than warm or hot water, which Schaffner says could have "significant implications toward water energy."

So what happens now? As is typical, further research.

"Understanding what behaviors and human factors most influence hand washing may help researchers find techniques to optimize the effectiveness of hand washing," according to the study's abstract.

The BBC pointed to a host of hand-washing recommendations from Britain's National Health Service, the Global Hygiene Council and the World Health Organization. These included washing your hands for about 20 seconds, rubbing your palms with your fingers interlaced and using a disposable towel when turning off the tap.