Hot Water Kills Bacteria while Hand Washing: Myth or Reality?
Like many people I believed in the advice that you should rinse your hands under hot water before and after applying soap to kill bacteria. Until today, that is.
The New York Times (apparently 4 years behind in their news) noted today that a 2005 report in the Journal of Occupational and Environmental Medicine concluded that:
“in studies in which subjects had their hands contaminated, and then were instructed to wash and rinse with soap for 25 seconds using water with temperatures ranging from 40 degrees Fahrenheit to 120 degrees, the various temperatures had “no effect on transient or resident bacterial reduction.”
No need to wash your hands with hot water anymore? There are 4 reasons why I absolutely love this little tidbit:
- You don’t have to wait for the water to heat up to wash your hands – saving you (significantly) on your water bill. How much does it save? Measure it.
- Saving water is certainly good for the environment.
- Your water heater doesn’t have to kick on to heat the water that you use – saving you on your energy bill.
- Saving energy is good for the environment as well, my friends.
Taking it a step further, turn the water off while soaping your hands. So go tell all your friends, save some cash, save them some cash, and do your little part in minimizing our impact on the environment.
Frugalhead Opinions:
- Like me, have you always believe that hot water helps disinfect your hands?
- Are you going to start using cool or at least luke warm water while washing your hands to save money and the environment after reading this news?
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Would everyone think less of me if I confessed that I’ve never waited for the water to warm-up anyway? It’s always been a patience issue of mine.
@ Broke MBA – Nope. I believe that makes you a wealthy environmental steward, albeit one with ADD. Just kidding.
As and EMT and a CNA I feel that I should comment on the fact that this study (while 4 years old) has yet to be reproduced and has not become generally accepted fact by the medical or scientific community. While at work and during food prep, I will continue to use the hottest water my hands will tolerate.
I’m not sure I believe that, especially seeing as the research is four years old. All the info on preventing the spread of swine flu here in the UK released over the last six months definitely says to wash your hands with warm water.
I have never heard that the water must be hot. I have heard that antibacterial soap is TOTALLY unnecessary – that regular soap is just fine and that plain old water alone is enough to kill most bacteria.
@ Jil.B – thanks for chiming in. I just can’t imagine though that hot water does much. When you think about it, you need to boil water for a minute or more before it has safely killed most bacteria… so how does warm water for a few seconds do it on your hands??
@ Frugal – perhaps we should all just wear little snap on nylon gloves???
@ Honey – I’ve heard that as well.
Your hands really can’t stand water outside of the range of 32-115 degrees F for any sustained period of time. With that said, bacteria can survive, this range with many thriving in the upper portion of this range. Water really does little to aid in the killing of bacteria on our skin.
@ Trevor – great point. I was thinking the same thing. I don’t understand how non-scalding hot water is supposed to kill bacteria.
It is well known that bacteria in water systems thrive in temperatures between 23 & 40 degrees C, best example is Legionnaire Disease. To say that there is a need to use boiling water does not hold “water”. Water that has been boiled & then allowed to cool to just over 40 degrees C does remove bacteria. Water below 23 degree C will also remove bacteria as long as the source can be assured as bacteria free in the first place i.e. treated water. Cold water from a non-treated source cannot be trusted & therefore boiled first.A good guide to how long to wash ones hands, a most important part of the procedure, is to “sing” Happy Birthday. This is approximately 15 seconds.
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