How do you get water intoxication?

Water overdriking: If one drinks excessive amounts of water without any salt or mineral intake one can develope hypo(low) natremia which can lead to lethary, somnolence and rarely weakness, seizures and death.

Diluting sodium leve: Water consumed in very large quantity can be poisnous.It only happens during water drinking cotests and drinking water after strenous exercise when there is loss of salt and just drinking water will dilute the sodium more.It can also happen in certain medical conditions causing hyponatremia. Causes swelling in brain .Causes headache, confusion, irritability and drowsines, seizures, coma and death.