Water intoxication or hyponatremia can result in death. the primary cause of hyponatremia is drinking enormous amounts of water, which dilutes the salt in the body to a dangerous level. As the electrolyte levels (as dicussed) get dangerously out of balance, body systems begin to fail and the sufferer exhibits signs of crisis such as diarrhea, over-salivation, stupor, vomiting, muscle tremors, confusion, frequent urination and other general symptoms of illness, and their brain begins to swell. This swelling is called a 'brain edema' or 'cerebral edema' and can lead to brain damage, paralysis, and sometimes death. (Source: Elowid Medical)