What is the point of this anyway? I remember carrying water to my flight at PVG and it sits in a holder in my backpack, so it wasn't visible there was water. One of the security guys at the jetway asked if it was empty. I wasn't thinking properly so I said yes and I was waved through. I then realized I lied not even understanding what was going on. I thought he meant if I emptied it through the initial security, which I obviously did, and then filled it up by the drinking fountain next to my gate.

I also remember having my bottle of water and 2 Sprites smuggled from the SQ lounge at HKG thrown out by the gate security. Boo. I'm a heavy liquid drinker, so I prefer to at least have my 1L water bottle filled up before I board.