A few more links:
Why is too much water dangerous?
WHO, WHAT, WHY?
The Magazine answers... :
http://news.bbc.co.uk/1/hi/magazine/6263029.stm
Ms Strange had hoped to win the video game system for her three children believing a few extra pints of the thirst-quenching would do no harm besides overloading the bladder. Participants first started off on small 220ml (8 ounces) bottles of water at 15-minute intervals. Those who progressed beyond five or more bottles without showing any discomfort were then given larger bottles to drink.:
http://www.earthtimes.org/articles/show/20261.html
Woman loses life over a Wii
By CRISTINA JEWETT
McClatchy News Service
SACRAMENTO - Contestants in a radio stunt called ''Hold Your Wee for a Wii'' have revealed new details about an on-air water drinking contest that left a 28-year-old mother of three dead.
Jennifer Lea Strange died after drinking well over a half gallon of water Friday during the ''Morning Rave'' program on KDND-FM. About 18 contestants vied for a Nintendo Wii gaming console by drinking as much water as they could without going to the bathroom; Strange took second place.:
http://www.miami.com/mld/miamiherald/16466226.htm