Water Intoxication (too much water or Overhydration can kill you!)
Water intoxication, also known as water poisoning, is a potentially fatal disturbance in brain functions that results when the normal balance of electrolytes in the body is pushed outside of safe limits (e.g., hyponatremia) by overhydration, i.e., over-consumption of water.
Under normal circumstances, accidentally consuming too much water is exceptionally rare. Nearly all deaths related to water intoxication in normal individuals have resulted either from water drinking contests in which individuals attempt to consume large amounts of water, or long bouts of intensive exercise during which electrolytes are not properly replenished, yet excessive amounts of fluid are still consumed.[1]
Water, just like any other substance, can be considered a poison when over-consumed in a specific period of time. Water intoxication mostly occurs when water is being consumed at a high quantity without giving the body its proper nutrients it needs to be healthy.[2]
Excess of body water may also be a result of a medical condition or improper treatment, see "hyponatremia" for some examples. Water is considered the least toxic chemical compound, with a LD50 of 90 g/Kg or more. [3]