Are you a pepcid-popper? Do you carry a roll of Tums in your purse? Water is the hero of the gastrointestinal tract. It is the basis of every fluid your body needs for digestion, including saliva, bile, stomach acid, pancreatic juices and even the mucus that lines our GI tract. Without adequate water the whole digestive system goes into emergency mode, and you may get heartburn, indigestion, constipation, hemorrhoids, and even ulcers.