
Washing Hands in Hot Water Wastes Energy, Study Says - andrewhillman
http://news.nationalgeographic.com/news/energy/2013/12/131213-washing-hands-hot-water-wastes-energy-health/
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ianferrel
I always thought the purpose of hot water was to improve the reaction between
the soap and the oils on your hands.

Use cold water, and the oil thickens, which makes it harder to emulsify, and
less likely to get washed away in the water. Use hot water, and the oils are
easier to wash away. Oils can trap dirt and bacteria, so washing them away
makes your hands cleaner.

There's a telling quote from the article that makes me think they're not
really studying what they should: " Even water as cold as 40°F (4.4°C)
appeared to reduce bacteria as well as hotter water, if hands were scrubbed,
rinsed, and dried properly."

But how do they fare when hands _aren 't_ scrubbed rinsed and dried properly,
and does the average person scrub, rinse, and dry their hands properly? More
importantly, are they more likely to do so if the water is pleasantly warm? If
hot water helps in the actual common case, then it's still important.

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stefantalpalaru
You're right. They also think that the purpose of washing one's hands is
killing germs instead of removing them from the skin.

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steven2012
I'm in my 40s, but I only learned in the last ~10 years that soap didn't kill
bacteria, but only helped remove bacteria that was stuck in the oil in your
hands. My sister, who is in the medical field, told me this and at first I
refused to believe her because the idea had been with me basically my entire
life.

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vietor
Interesting from a biology/chemistry perspective, but also perhaps a really
good example of missing secondary effects.

"The agencies do recommend using soap and water and scrubbing vigorously, for
at least 20 seconds."

I spend a whole lot more time scrubbing when the water is nice and warm.

""You don't need hot water, you need soap, water, and friction," said Sack. He
added that the Escambia County Health Department in Pensacola, Florida,
decided to turn off the hot water heaters in its five clinics two years ago,
after a review of the literature provided no evidence that hot water was
better."

... and did turning off the hot water have impact on compliance with hand
washing policy? That would be an interesting follow-up study.

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greenyoda
The researcher interviewed in this article, Amanda Carrico, has three degrees
in psychology.[1] I'm not sure why I should trust her to do a review of the
microbiology literature.

[1] [http://www.vanderbilt.edu/viee/profiles/amanda-
carrico.php](http://www.vanderbilt.edu/viee/profiles/amanda-carrico.php)

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bcoates
"if hands were scrubbed, rinsed, and dried properly."

... which never happens. Seems like the same faulty logic used to justify
blow-driers over paper towels.

It doesn't look like the study that would actually answer this question
(randomly assigning bathrooms heated and unheated water, doing hand swabs on
leaving patrons) has actually been done, but if I were in a position to gamble
on the outcome, I'd bet the cold water bathroom gets substantially less
effective cleaning for human-factors reasons.

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B0Z
Maybe. But my hands feel better with hot water.

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clubhi
This whole time I've been taking hot showers for nothing.

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orthecreedence
IF you use cold water, your body has to make up the lost heat. This requires
energy which comes from burning calories, meaning you will have to eat sooner.
Food is not free energy, and in many cases is probably a lot _less_ efficient
energy-wise than hot water when you think about the energy it takes to grow,
prepare, package, and ship it.

This is why I started the Lukewarm Water Hand Washing Awareness Coalition
(LWHWAC). We've been fighting for years to raise awareness of the dangers of
washing hands in both hot and cold water by lobbying to get our messages in
schools, holding bake sales, running TV and radio advertisements, streaking
through hot water heater sections of department stores, and holding flyering
campaigns.

~~~
qbrass
But so many people nowadays eat too many calories.

That's why I started the Cold Water Weight Loss System.

With a regimen of cold showers and washing your hands with cold water, you'll
shiver those pounds away in no time.

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iLoch
In other news: The sky is blue.

Well, it's actually grey right now. _Sigh._

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artacus
So the surgeon should use cold water before gloving?

It seems more sensible to heat the water at the tap like they do in Germany
and Barbados.

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banachtarski
Huh? Did you read the article?

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artacus
I confess to being facetious with my comment which is probably not cool
because though I believe this whole preoccupation with carbon emissions to be
a scam, the idea of wasting energy bothers me on a natural level, so that long
before global warming I washed my hands with cold water.

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djent
Shouldn't the use of good antibacterial soap remove most [99%, as advertised]
of the bacteria anyway?

~~~
pkroll
No: those antibacterial soaps are advertising a number that is the same as
regular soap. They're no better in getting rid of bacteria, and may contribute
to antibacterial resistance. [http://health.howstuffworks.com/skin-
care/cleansing/myths/qu...](http://health.howstuffworks.com/skin-
care/cleansing/myths/question692.htm) (but a quick search will net you plenty
of other refs)

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geraldvdp
I knew it!

