Why do we have to surrender all the water before entering the airport even if we prove that is in fact a drinking water by taking a sip?

Question

But once inside the airport terminal, we can always buy some water and no one will check anymore if you bring the water inside the plane.

In: 974

Answer 1

You can take a sip of anything, it doesn’t prove anything about the contents.

I’ve actually done this, with vodka, and tried to keep a straight face, when entering a music festival