Why can't we bring water in an airliner
How did I ruled out the first reason: (this is important for airport operators and airliners), water and alcoholic beverages could be easily made into explosives. We could bring the tools to extract the explosives substances on water without the security noticing it. And then build the extractor aboard the plane.
Thus creating a mini bomb, a very low explosives that won't destroy the plane, however enough for scaring everyone on board! I won't tell you what to bring, how to do it, and I will not hijack any plane! This is a warning for airport operator and airliners! The tools are available on daily live and did not appear very scary.
Anyway, did you know that it is perfectly safe to bring bomb on board an airliner? Bomb won't explode unless being deliberately triggered. Here is the proof: the jet fighters and bombers all around the world brought explosives onboard everyday! And they are save on board and did not explode!