Handwashing with cool water is just as good for killing bacteria

For years we’ve been taught that, when washing hands, we have to use hot water to effectively remove bacteria.  But a new study published in the Journal of Food Protection has found no difference in washing effectiveness when hands were washed in water that was 16, 26 or 38 degrees C.  (Note: for reference, 16⁰C is a bit warmer than the water coming out of your cold water tap, but it’s colder than you’d want to swim in.)

The implication: in the words of one of the study’s authors, “We are wasting energy to heat water to a level that is not necessary.”

So – something to think about the next time you wash your hands.  Cool water is much more comfortable in summer anyway!

PS: interestingly, the biggest factor in washing effectiveness was washing technique; antimicrobial soap had little effect.