I know a guy that died from water fasting. Also saw a Discovery doc years ago about a guy that died of dehydration in the desert next to a water spring, he had no access to salt.
Water intoxication, also known as water poisoning, hyperhydration, overhydration, or water toxemia is a potentially fatal disturbance in brain functions that results when the normal balance of electrolytes in the body is pushed outside safe limits by excessive water intake.