Water is the basic component of the human body. 60-75% of our body is made up of water. Total body hydration and the balance between water intake and excretion are homeostatically regulated and are necessary for optimal body functioning because they improve: Cognitive function Body temperature regulation Nutrient transport and absorption Normal kidney function Normal heart function Dehydration is the condition seen when the body loses more fluids than it takes in. Mild dehydration is common and usually caused by low fluid intake throughout the day. Fluids are constantly lost through normal bodily functions such as sweating, breathing, and urination.