“How much water should a gastric bypass patient drink?”

Bypass patients don't need to change their drinking habits much at all. You will be able to absorb water normally so just drink enough water to urinate several times per day. You will need to reduce food intake because the gastric pouch is so small and cannot hold much food. Liquids, on the other hand, easily pass the stomach pouch and go into the small intestine and get absorbed there normally.