What are the exact reasons why one cannot take a bottle of water on the plane?

  • So what exactly are the reasons:

    • policy by the airlines?
    • slowing down security?
    • What if it's 100mL of water filled in one of those tiny travel bottles that people use to downsize their toiletries?

    I was just discussing this topic with a friend & then realized while I know of the rule I would like to know all the aspects as to why.

    AFAIK you can take a bottle of water on the plane, just not through security. You could for instance take an empty bottle through security and then fill it up at the gate.

    @drat: that is what I do all the time - empty my bottle before security, fill it up before getting on the plane (e.g. Chicago airport even has bottle-filling stations airside)

    @Jonas: In various places, such "bottle-filling stations" are commonly known as "taps" :)

    @O.R.Mapper: The fact that there are bottle filling stations specifically to fill water bottles indicates that bringing filled bottles onto the plane is acceptable practice. Of course, there are a few airports with only warm water taps, presumably to encourage buying water.

    @Jonas: Why would taps be limited to warm water? In any case, I think I didn't explain my intentions clearly; I totally agree it is considered an acceptable practice to bring filled bottles onto the plane. I just wanted to point out that, having grown up in a region where tap water is generally drinkable, there is a much more universal way of refilling bottles (i.e. publicly accessible taps, e.g. in bathrooms) and the installation of specific appliances such as "bottle-filling stations" is not necessary and would rather be a waste of resources, because water is already available from taps. ...

    ... Maybe some dedicated bottle-filling stations are indeed provided to encourage filling bottles and bringing them into the plane. On the other hand, those could also just as well be meant for general convenience in the security area, similar to the food stalls in the security area, which are used by people waiting for their departure, and which *can* be used by people to buy food to bring on the plane. However, I'm quite sure the food stalls in the security area are not in any way intentionally meant to encourage passengers to buy their food on the ground rather than on the plane.

    Just as a note, while the comments so far are correct that you can _usually_ buy or fill a water bottle in the terminal and take it on with you, this is not _always_ the case. In particular, some international flights actually confiscate water bottles at the gate or even inside the boarding bridge. See this question and this question.

    @reirab Confiscation at the boarding bridge? How is that a security thing? Lol.

    I once read (source: the internet!) about a guy who tried to bring a bottle frozen water through security, claiming that, hell, "it's not liquid!"!

    It's all risk ratio. If there is a risk that some less than stable person might hide an explosive as a bottle of liquid, then banning all liquids of a usable size is an easy win. It's easy to do, the beaurocrats can publicize that they've "done something" to prevent "terrorism"... the weak minded can applaud their "something"... it's win all around.

    @LéoLam That's hilarious that TSA officially responded to xkcd. I'm not certain that I agree with their conclusion that a water bottle full of liquid explosives is really more dangerous than a lithium battery, though. Lithium is _extremely_ reactive. Inadvertently mixing (relatively small amounts of) Lithium with water is how people blow themselves up with meth labs.

    Security staff work strictly to the rule book. Apparently no discretion is permitted. In this situation common sense has no place. As a regular traveler I've always thought the more they inconvenience innocent clients, families,old folk etc the more they justify their jobs. Airports and airlines are simply there to make money. Aggravation through the airport achieves this. Customers are secondary. Does anyone really know if I can take an empty Thermos flask through security please?

    Personally, I believe the only right answer is (because of) inertia. Once implemented by a bureaucracy, a rule takes on a life of it's own and rescinding it is much harder. Making a rule for safety is an easy decision for a government employee or agency, after all, it's for safety. Rescinding it is exponentially harder. After all, I know *I* would not want to be the government person/agency that said a rule is no longer needed, only to have that what was protected against happen. Then you have to prove why you considered it no longer a threat. ...

  • lambshaanxy

    lambshaanxy Correct answer

    6 years ago

    Because it's difficult to tell apart a bottle full water from a bottle full of a chemical like hydrogen peroxide that could be used to make liquid explosives. There was one hare-brained terrorist plot that apparently tried this in 2006, and because "passenger convenience" will always lose out to "bureaucratic ass-covering" when it comes to security theater, all liquids of all kinds were banned by the TSA. (Unless they're under 100ml, so yes, you can take a 100ml bottle of water on board... if you can find one!)

    In Japan, they've already got bottle scanners that can identify suspect liquids. These are increasingly being adopted by other countries, and once they're widespread enough, the liquid silliness will hopefully end.

    Note that while you can't take a partly or completely filled >100ml water bottle through security, it's perfectly fine to take an empty bottle through security, and fill it up before you board the plane. Or you can buy a bottle once you've passed security.

    Are 100ml of hydrogen peroxide not sufficient to make liquid explosive? Or is it just that the explosion might not kill everyone on the plane? Ah you gotta love security theatre.

    @JonStory For maximum security, you could live in a bunker and never fly! Discussions on if the current rules are actually in any way sensible or proportional probably belong on Skeptics.SE though

    I like how, having confiscated what could be a bottle full of explosive, they (often) throw it into a box containing a lot of other previously confiscated potential explosives.

    This is getting a bit off-topic. Perhaps someone should post the question, "Ways of blowing up a plane with at most 100ml of liquid".

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Content dated before 7/24/2021 11:53 AM