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Is hand-washing after urination and defecation merely a product of social norms, or is there a health-related reason that we wash our hands after going to the bathroom? Or is there some other reason altogether?

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    Offered without evidence: Just one of the reasons to wash your hands after using the bathroom, is that proximity to a hand-basin offers a good opportunity to wash your hands several times a day, which is good hygiene practice in itself.
    – Oddthinking
    Jul 17, 2012 at 2:23
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    In one Southpark episode it is said that it would make more sense to wash your hands before you go to the toilet, because your hands are probably much dirtier from all the stuff you touched than they can get from touching yourself.
    – Baarn
    Jul 17, 2012 at 12:46
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    I suspect that this is going to be somewhat dependent upon what you are doing in the bathroom and how you go about doing it. I've heard that for males that hand-washing is effectively unnecessary, assuming that they don't touch any of the bathroom surfaces due to the fact that urine is sterile.
    – rjzii
    Jul 17, 2012 at 12:51
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    @Jodrell If the amount of fecal matter is miniscule to where it is difficult to see with the unaided eye, which is often the case, I think this is a valid question. Am I going to catch a disease from myself? I don't think so, because then I would already have it.
    – Cory Klein
    Jul 17, 2012 at 15:44
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    @Cory From yourself – no. But potentially from other people who you touch – either indirectly or via touching the same objects as them, and who failed to wash their hands after getting into contact with pathogens from the urinary or intestinal tract. Jul 17, 2012 at 20:40

1 Answer 1


Without washing your hands after going to the toilet, you are running the risk of E. coli enteritis. E-Coli can lead to severe illness or even death. Keep in mind, every time you flush the toilet that a plume of water droplets can spread by up to a couple of metres, coating tooth brushes and such in contaminant. This is also backed up here.

In response to OddThinking: If you were to only touch yourself I would reason that the risk remains. As noted above, everything within a few metres of the loo is likely to be swimming in bacteria, especially if the lid was not closed when it was last flushed. So just entering the bathroom is problematic.

Furthermore, people fart about a litre of gas a day. Since farts contain bacteria, you can pretty much assume your clothes and body are also contaminated. This was posted on Dr Karl's site. The Naked Scientist tested the effect of clothing on bacterial content of farts and found the clothes (jeans + undies) seem to absorb the bacteria.

Taking this further: can you make yourself sick with your own facel material? Given that 20% of food poisoning occurs at home, I would think so.

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    Your references seem to (quite rightly) recommend washing your hands to avoid contaminating others. However, this doesn't address the question - can you make yourself sick?
    – Oddthinking
    Jul 17, 2012 at 2:27
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    @Oddthinking - updated. I'm still not 100% convinced though. Certainly my cat seems to suffer no ill-effects from self cleaning, and (please) let's not talk about 1 cup 2 girls.
    – dave
    Jul 17, 2012 at 2:52
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    Isn't the fart-bacteria you mention "good" bacteria in the digestive tract? Is it actually harmful? And even if it is harmful bacteria, then you're not going to make the situation worse by making your clothing or epidermis "contaminated" when it is already existing inside you in abundance. Am I wrong?
    – Cory Klein
    Jul 17, 2012 at 15:45
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    Also, you link "20% of food poisoning" to the wikipedia article for flatulence, which provides no reference to food poisoning, and specifically mentions that flatulence is not poisonous.
    – Cory Klein
    Jul 17, 2012 at 15:53
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    @KonradRudolph and Oddthinking - I think maybe we are reading a bit too deep into the question here. What inspired this question for me was that most of the physical objects I touch in the bathroom are used specifically for washing and drying my hands. After pooping I touch the toilet paper, but then it goes in the toilet. So to me it seems that the process of washing hands introduces more touch surfaces, and that additional risk may be obviated by just not washing at all. So everyone says we should wash our hands when using the restroom, but is that really true? Does that really help us?
    – Cory Klein
    Jul 18, 2012 at 15:00

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