In the movie kingsmen, (spoiler alert) a room is flooded with water. To stay alive, most of the characters stuff tubing into the available toilets and breathe through that. (you can see them in the picture below in the background)
I wonder if that's actually possible. Luckily, there was an immediate explanation given by another character afterwards for people like me:
For those of you who are still confused, if you can get a breathing tube through the U-bend of a toilet, you have an unlimited air supply. Simple physics... worth remembering.
Except that this explanation didn't make much sense to me. Is this a case of simple physics or rather Hollywood physics? If the room is full of water, each toilet will act as a drain. The trap (which I guess "U-bend" in the quote refers to) will not act as some kind of barrier. The water going down the drain will displace the air in the plumbing. Making it impossible to breathe through the toilet.
I'm not exactly into fluid dynamics, but even if there was some air left in the plumbing , wouldn't it be extremely difficult to suck it out, because of the stream of water that surrounds it due to the Venturi effect?