Feces is usually about 40 percent water and 60 percent solid matter. reducing the water content to 20 percent would most likely result in

Constipation

Explanation:

An organism's bowel movement depends on the amount of water it has consumed. If the organism has not consumed enough water then the stool becomes hard and dry.

This makes it difficult for the organism to pass the stool. This condition is known as constipation.

Hence, here if the water content is reduced to 20 percent then this would likely result in constipation.