But a bottle of water is still highly dangerous!
The problem is when the water isn't water.
They discovered years ago after that movie with the liquid b-ombs (can't think what it's called - had a yellow and red liquid) that more than 100mls of one liquid mixed with more than 100mls of another, could cause a catastrophic explosion - hence the liquid limit. I'm happy they have the limit but not happy when I purchase a water in the terminal only to find an additional screening point at the departure gate