Too much water intake may lead to hyponatremia, which is a drop in your blood sodium levels. Sodium is an important electrolyte that regulates water distribution in the body. But if you outdrink more than what your body can excrete, then you may experience water intoxication, nausea, or a disruption of brain function. This can happen if your cells are overhydrated, making them swell, and as your brain is an enclosed area, the swollen cells may put pressure on the brain, which can even be fatal.