Originally Posted by SchmutzigMSP
Peroxide also looks like water.
They could simply ask everyone to taste the water, or even just smell the open bottle like they do in China.
The problem with that is that I read that the terrorists were planning using sports drink containers with a false bottom, so that they could drink the drink on top and still have the explosive precursors on the bottom.
I'm not totally sure how this can be resolved unless the airports sell "secured water". However, one of the terrorists arrested worked at the airport, so I'm not even sure that will help.