What are common symptoms of tap water poisoning?

Mental status change. This is a rare condition that present with changes is mental status such as personality and behavior, headache, confusion, irritability and drowsiness, or muscle weakness. It can progress to seizures and coma. These symptoms are the result of brain swelling and electrolyte (sodium and potassium) imbalance. Drugs (ecstasy) and excessive water during excessive exercise are some causes.