If too much water is reabsorbed back into the body's system, the stool texture will be hard and dry causing constipation. If not enough water has been reabsorbed back into the body's system, the stool texture will loose and watery, causing diarrhea. Water absorption affects stool texture along a continuum of loose and water to dry and hard. Water absorption itself is affected by length of time in the intestine. Too short a time corresponds to loose, watery texture while too long a time corresponds to dry, hard texture.
Normally stool is very watery, when the colon absorbs water the stool slowly solidifies (normal poop), when it absorbs too much the person usually gets constipation but when the colon doesnt absorb enough the stool comes out as diarrhea