Water is a Weapon at the Airport

Nowadays you have to discard your water or other liquids before you can enter the secured area of the airport. This is where they  put you through the body scanner or the metal detector and examine you and your stuff. Up until this magical point you can have your beverages and they will sell it to you or you can drink from fountains.

Immediately after you  go through the  security area you are sold water, pop or booze,or can fill your empty bottles back up and you are given water and beverages on the plane. 

If liquids  ( more than 3ounces) can make bombs-  why are we ever allowed to have  4 oz of liquids at all- Anywhere?
Quite frankly, the worst problem I have ever seen as a result of  a good size fluid intake was long lines  for the bathroom .