The intestinal tract uses much water to break down solid foods. It has to liquefy the dissolvable components of solid foods to extract their essential elements. Whatever can be dissolved is then absorbed into the blood circulation and transferred to the liver for processing. The refuse that cannot be further broken down is then passed on through the various segments of the gut and gradually compacted for elimination.

Depending on the adequate availability of free water in the body, the refuse will carry with it some of the water that was used to liquefy the food. What water it can carry with it will act as a lubricant to help the refuse move through the large intestine. The last segments of the small intestine and most of the large intestine are under the direction of the water regulators to reabsorb as much of the water in the refuse as might be needed by the other parts of the body. The more the body is in need of water, the more there is a determined effort to reabsorb the water that is available in the intestine. This process puts a drastic squeeze on the refuse to separate its water content and make it available for reabsorption by the mucosa or lining membranes of the large intestine.

The more the body is dehydrated, the slower the motility of the lower intestines in order to allow time for reabsorption of the water content of the refuse. This process of preventing water loss is another of the body's water-preservation mechanisms. One part of the body where water loss is prevented in times of drought management is in the large intestine, through adjustment of the consistency and the rate of flow of the excrements. When the passage of refuse from the large intestine is slowed down, the mucosa absorb the water, and the feces become hard and not fluid enough to flow. The act of expulsion of solid feces becomes difficult. To prevent this process from taking place, added intake of water and some fibers that hold the water better seems to be the only natural solution to constipation. Remember that hemorrhoids, diverticulitis, and polyp formation are common occurrences with constipation. Chronic dehydration and its consequential constipation are primers for cancer formation in the large intestine and the rectum.

Reabsorption of water in the digestive tract also involves the regulating valve between the last part of the small intestine and the first part of the large intestine, known as the ileocecal valve. The valve shuts down and allows the small intestine time to get as much water possible out of the as-yet-unformed refuse. At certain levels of dehydration, the closing of the valve may become too forceful and may cause spasm. This spasm will translate into pain in the lower right side of the abdomen.