Get a 1 liter Nalgene bottle that you can carabiner-clip to your carry-on.
Take it EMPTY through the Security checkpoint.
Fill it with the "highway robbery" bottled water from the newsstand.
(Drink at least 8 oz/hr of flight time)
Sweet-talk the flight attendants into refilling when needed with the bottled water they get catered with.

(Is it obvious I fly A LOT?....)

The TSA rule is "3-1-1"
3 oz bottles of shampoo, conditioner, shave gel, shower gel, hand sanitizer, etc, are permitted.
http://www.tsa.gov/311/