Hand Washing 101: Forget Everything Your Mama Taught You

washing hands

New research about effective hand washing proves that most of us have been doing it wrong–and it’s costing us millions.

What’s your hand washing technique? Here’s what I do:

1. Crank on the hot water tap
2. Wait a few seconds while it warms up
3. Stick a finger in and realize it’s now too hot
4. Open the cold water tap until it’s warm but not too warm
5. Pump soap into my palms
6. Lather, then rinse, then dry

You were probably doing something similar, and thus taught your kids to do the same. The idea is that the combination of hot water and soap during hand washing kills germs so that we don’t get sick or spread disease to others.

According to Amanda R. Carrico, a research assistant professor at the Vanderbilt Institute for Energy and Environment in Tennessee, however, it’s just an old wives tale. There’s no scientific proof that hands washed in hot water get any cleaner than those washed in cold water. Meanwhile, our obsession with warm tap water is wasting a ton of energy.

Carrico told National Geographic’s Brian Clark Howard that “after a review of the scientific literature, her team found ‘no evidence that using hot water that a person could stand would have any benefit in killing bacteria.'” What they did find was that the billions of hot water hand washing episodes performed each year are taking a significant toll on the environment (and we’re not just talking about wasted water).

Heating water for hand washing results in 6 million metric tons of CO2 equivalent emissions annually, which, according to Nat Geo, is “roughly equal to the emissions of two coal-fired power plants, or 1,250,000 passenger vehicles, over the course of a year.”


According to the CDC and other health authorities, effective hand washing depends less on the temperature of the water and more on your soaping technique, as well as how long you lather. So in the New Year, I’ll only be reaching for the cold water tap, and training myself to sing through “Happy Birthday” twice before I rinse. Quietly, of course.

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Image: arlingtonva