For a radio contest. If you are wondering how water can kill you, the BBC has a nice little write-up. Here is the jist:
Jennifer Strange had taken part in the “Hold Your Wee for a Wii” game, which promised the winner a Nintendo Wii. Afterwards she reportedly said her head was hurting and went home, where she was later found dead. Initial tests have shown her death is consistent with water intoxication.
Drinking too much water can eventually cause your brain to swell, stopping it regulating vital functions such as breathing, and causing death.