* Buy a bottle of water or another drink once you are through - once you are through security, you can buy liquids more than 100ml but not before (stupid I know). Never assume you will get a bottle of water on the flight.
It's because all liquids behind the security gates have been vetted before they come in, so theoretically security can be sure the bottle of water is not nitroglycerine.
If you wanted to smuggle something on board a flight, I reckon that would be the way to do it - slipping it into the stock for the shops somehow.