Water is a very important substance in the body making up approximately 70% of it. Over 50% of that water is found in cells referred to as the '''intracellular fluid'''. The remainder makes up the base of the fluid surrounding the cell which is referred to as the '''extracellular fluid''' or '''ECF'''. | Water is a very important substance in the body making up approximately 70% of it. Over 50% of that water is found in cells referred to as the '''intracellular fluid'''. The remainder makes up the base of the fluid surrounding the cell which is referred to as the '''extracellular fluid''' or '''ECF'''. |