What I do is to put the cap in my pocket. If challenged it is then arguably a drinking container like a cup - not a bottle. Put the top in another bag or your coat pocket.
Plastic bottles rarely get picked up by x-ray, the only time I can remember is at ATL but the TSA agent was happy enough when I said that it was empty. I suspect that a metal one might.
One of my personal dislikes is airports that do not have drinking fountains airside. US airports are good in this respect, the larger hubs are OK, leisure airports can be awful - I think that they see selling bottled water as a revenue stream. You can also use water from taps (doubtless hygenic but I generally carry water purification tablets in any case) but when they are mixer taps - ugh!
My other pet hate is secondary security which specifically prevents you taking water on board. Security yes, but if you can't trust primary security whats its point?
Last edited by Peter47; 12th Aug 2012 at 19:54.