Another report shows the development of hyponatremia with water intake of 2.5-5.6 gallons, or 10-20 liters, in just a few hours (5). A case of water intoxication and prolonged hyponatremia also occurred in a healthy, 22-year-old male prisoner after he drank 1.5 gallons (6 liters) of water in 3 hours (1).read more >>