Is it serious to drink 6 litres of water per day?

Risks vs. Benefits: Patients with kidney stones benefit from drinking enough to void 2 liters a day. Patients with a disease called diabetes insipidus, lose large volumes of water and need to keep their intake up. Patients with abnormal kidney function, or on diuretics can retain water and have develop hyponatremia. For the rest of us, excess water intake is voided.