water bottle experiment ...eeewwww

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    Jun 17, 2007 10:38 PM GMT
    Recently, I was giving people a bad time about eating sushi, but then tripped over a bad habit of my own. Sometimes I leave the water bottles on my bike, in the garage, between rides. Sometimes this means I have to dump out the "old" water and fill them with fresh just before a ride.

    Last week, I did a little testing on those bottles. (OK, I was supposed to be doing water quality testing anyway, but went riding in the middle of the day. By taking a few samples, I can say "I was working... honest!")

    Experimental design: I measured bacteria in my tap water, and in my freshly rinsed and filled - but stored wet - bottles. One previously contained tap water and the other previously contained 1/2-strength gatorade, a few drops of which were probably still in the bottom. I also tested all of the samples for coliform and fecal coliform bacteria, which are the standard indicators for evaluating disease-causing potential in food & water.

    Results:
    Tap water 340 bacteria per ml
    water bottle 114000 bacteria per ml
    gatorade bottle 3800000 bacteria per ml

    Both of the bottles failed the presumptive coliform test, but they both passed the confirmatory fecal coliform test.

    Discussion:
    Yikes! There appears to have been quite a lot of bacterial growth in these bottle while they sat, wet, on the bike frame for a couple of days. Enough so that loads of bacteria carried into the fresh water, even after the bottles were rinsed. The coliform test suggests that the bacteria came from a mammal (probably backwash) but at least they were free from intestinal bacteria (I'm not THAT dirty.)

    Deciding whether or not to worry about this raises an interesting question: Can you make yourself sick by consuming bacteria & viruses that already came from your own body? I'd guess not (barring buildup of some toxin, such as botulinum). Certainly, there would be a huge risk of transmitting disease organisms to a second person, if these bottles were shared.

    Conclusions:
    Always wash out your bottles with detergent when you're done for the day, and allow them to dry. A drop of bleach once in a while wouldn't hurt.

    Never share water bottles with anybody, unless, I suppose, you already have a spit-swapping sort of relationship with them.

    Even without putting numbers to it, this ought to be common sense, obviously. (Notice that bike racers on TV accept water from fans, but they pour it on their backs and never, ever drink it.) Still, I wonder how many of us actually scrupulously clean our bottles?


    (This concludes my creative time-wasting for the day.)

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    Jun 18, 2007 5:15 AM GMT
    Well, I'm glad you aren't pooping in those bottles mindgarden. LOL. But let me get this straight: you filled bottles with either water or 1/2 gatorade left them for a couple of days, and then poured the contents out, rinsed the bottles and replaced with fresh water which you then tested?
    Also from what you say this has been your standard practice, sans problem, for quite some time. Well now the next logical step would be to see if really would transmit the bacteria in the form of an infection by sharing the bottles. Any volunteers?
    Personally I probably wouldn't do anything, but then again I will happily drink from possibly contaminated sources -- usually mountain streams, and other dubious sources while travelling. Not recommended, but so far I have escaped unscathed.
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    Jun 18, 2007 7:17 AM GMT
    very interesting. i majored in microbiology in college. did you actually go about plating the water samples or did you use another kind of media like Colilert? i remember doing experiments on food in my applied micro class. granted, not many things are sterile, but its amazing what quantities of bacteria are considered "acceptable"
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    Jun 18, 2007 2:03 PM GMT
    mindgarden-

    Wow, even your tap water seems high. Isn't the bathing water standard 1000TC/100ml?
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    Jun 18, 2007 2:31 PM GMT
    The numbers that I mentioned were total aerobic heterotroph, not coliforms. That's a pretty ordinary number for well water.
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    Jun 18, 2007 2:32 PM GMT
    I would assume that a significant source of bacterioform would be the ride itself. I don't know how many times I've looked down on a trail ride at my water bottle to find it dusty and/or muddy...
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    Jun 19, 2007 12:01 PM GMT
    I never use my bikes water bottle, mostly because the taste of water from plastic is gross to me and plastic seems to better cultivate germs and bacteria than glass. However, I recgonize that a little bacteria is good for you - it just tastes better from a glass.
  • MikemikeMike

    Posts: 6932

    Jun 19, 2007 3:15 PM GMT
    I never reuse a water or Gatorade bottle!!
  • trebor965

    Posts: 200

    Jun 19, 2007 3:31 PM GMT
    poop drinker
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    Jun 19, 2007 4:53 PM GMT
    Well there you go mindgarden: plastic vs. glass and which grows more bacteria. I know I'd be curious to know.
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    Jun 19, 2007 5:02 PM GMT
    In the words of Cleveland from Family Guy:
    That's Naaasty!
  • MSUBioNerd

    Posts: 1813

    Jun 19, 2007 5:11 PM GMT
    Plastic will almost certainly grow more samples. Glass is unreactive chemically--most glass is merely SiO2, though there are borosilicate versions which do better at surviving substantive heat shocks. Think pyrex for you industrial and/or cooking types. Plastics, on the other hand, are nearly always a carbon-based polymer, and thus are a potential energy source in and of themselves for certain types of bacteria.

    Things like botulism shouldn't be a problem in a situation like this; the bacteria which produce the toxin are strictly anaerobic, and can't survive under oxygenated conditions. Further, while coliform counts are indeed a standard measure of potential disease in water samples, it should be noted that only a fraction of coli itself can cause illness when ingested. The E. coli my lab uses daily has been so domesticated that it's been joked that we could drink our cultures straight down and have no unpleasant effects other than that they'd taste horrible.

    At roughly 10^6 CFU/mL, that water bottle sample will be just at the edge of being visibly cloudy. 10^7 is detectable to the naked eye easily; 10^6 would depend on both your eyesight and your experience in trying to detect growth in dilute carbon sources. That gatorade bottle, in the 4 * 10^7 range, would be easily visible when compared to an uncontaminated sample.

    That being said, you can lose a huge amount of that by rinsing out the bottle. 10 mL is a standard sort of amount of liquid in a test tube, and probably more than you're leaving in the bottle when you dump it out. 1000 mL is a bit more than a 32 ounce bottle, and thus fits into most water bottles. It you assume that your total bacterial concentration is right at 10^6/mL, dumping it out and filling again will get you to 10^4/mL. Doing that a second time will get you to 100/mL, which is less than your tap water. Assuming you're filling it with tap water, then, 2 fill-and-dump versions of rinsing will make your water bottle about as clean as your tap water, and your gatorade bottle only roughly twice as dense with bacteria.
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    Aug 09, 2007 5:33 AM GMT
    I use the same bottle usually for about two to three days...commuting to work...However, keeping it in the fridge and leaving the top open keeps bacteria from forming, I also drink out of it constantly, when I am at school, I use a waterbottle for two weeks at a time...probably not a good thing now that I am apprised of this...thanks for the info, I suppose this means I will have to wash some dishes to?
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    Aug 09, 2007 6:00 AM GMT
    Hmm... I'd forgotten about this thread.

    I had a weekend guest who felt compelled to clean house, (hmmm... guess I'm not complaining) and he stuck all my bike bottles in the dish washer. They survived, so I guess they're dishwasher safe!

    HDPE and polycarbonate are relatively inert as carbon sources for bacteria. They'd probably get more nutrients from the water than from the plastic. And some microbes DO "eat" glass, but nobody is exactly sure why. Expensive lenses for sale in tropical countries are impregnated with antimicrobial chemicals because otherwise they'd get cloudy from mold etching in a few years. But those aren't the kind of microbes that can make you sick. Just fun to play with.

    E. coli isn't usually a pathogen (some strains are) but it's an indicator of all the other things that grow in humans but are harder to grow and identify. That is, if E. coli is there then Salmonella, hepatitis viruses and the like may be too.

    Oh, and the bottom of any container with an actively growing culture much over 10e7 is going to be anaerobic. Potato salad anyone?
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    Aug 09, 2007 6:57 AM GMT
    poop drinker