Hand Washing with Hot Water Unnecessary, Study Says

Published on December 16th, 2013 | by

Child Hand Washing

Hand washing with hot water is unnecessary, says a new study by researchers at Vanderbilt University.

Many of us were taught as children to wash our hands in hot water (and with soap) in order to kill germs that might be on our hands. It seems to make sense, since heat does kill bacteria. The problem with that is that the temperatures required to kill dangerous bacteria are higher than what our skin can stand.

Boiling water is often used in a pinch to kill bacteria, when hiking or camping or when a person is otherwise unable to access clean drinking water. However, the recommendation to kill bacteria is to boil the water for ten minutes. Skin touching boiling water for even a moment results in a nasty burn that requires first aid.

According to the study, the authors found that washing in water as cold as 40 degrees Fahrenheit did not kill bacteria any less than warmer temperatures. 40 degrees is a bit cold for most people’s comfort, but lukewarm water could be just fine.

Hand Washing How-Tos

The important steps in hand washing are:

  1. Wash with soap and clean water for at least twenty seconds – longer if your hands are greasy or very dirty.
  2. Remember to lather up the backs of your hands, between the fingers, and under the fingernails. Don’t forget the thumb.
  3. Rinse your hands with clean water.
  4. Dry your hands with a clean towel.
  5. Following up with a nice hand cream is optional.

The authors note that if Americans started using lukewarm or cold water to wash our hands, instead of hot water, the annual energy savings would be equal to that used by a small country like Barbados. The Escambia County Health Department in Florida has already shut off the water heaters in their clinics and save themselves $2500 per year.

Now using warm water when hand washing in order to keep your hands from getting too cold in winter? That still makes sense to me.

Child washing hands in bathroom photo via Shutterstock


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