When dehydration occurs, urination is going to be less frequent. Why? Because the body needs to store as much water as it currently has available to it. So it answer the question, urine is reabsorbed back into the body. This is a difficult question to be specific, because the body will reabsorb it into whatever needs it then most at any given time. Tissues, organs, you name it. It's a matter of the body trying to keep itself functional and alive. The correct answer is KIDNEYS.