Why are you drinking so much liquid? Are you drinking it to feel full? Are you drinking it because you're constantly thirsty?
If you're drinking liquid in lieu of eating and to make you feel full, that's one thing people with eating disorders do.
If you're constantly thirsty, that's a common symptom of diabetes.
You can actually die from drinking too much water - it's called water intoxication. You can flood your body with so much water, that you create an imbalance of electrolytes. Water intoxication is rare, but it happens. I remember a few years ago, a radio station held a contest of who could drink the most without relieving themselves - one of the contestants actually died.
http://en.wikipedia.org/wiki/Water_intoxication