Man, this sort of information can freak a guy out.
After doing some random searches for something that wasn't quite as random (I just can't remember what my initial search was for), I stumbled upon this bit of wiki-information regarding WATER INTOXICATION. It would appear that drinking too much water can actually lead to DEATH.
Yow. Now I'm going to think twice about drinking water while running - my whole life could be affected by this. Ayish!