Functions of kidney The kidneys are a pair of small organs that lie on either side of your spine at about waist level. They act as filters that keep your blood free of by-products and toxins The kidneys excrete these compounds with water to make urine They also eliminate excess body water while selectively reabsorbing useful chemicals and allowing waste to pass freely into the bladder as urine They allow you to continue to consume a variety of foods, drugs, vitamins and supplements, additives, and excess fluids without worry that toxic by-products will build up to harmful levelsFunctions of kidney • The kidneys excrete these compounds with water to make urine. • They also eliminate excess body water while selectively reabsorbing useful chemicals and allowing waste to pass freely into the bladder as urine. • They allow you to continue to consume a variety of foods, drugs, vitamins and supplements, additives, and excess fluids without worry that toxic by-products will build up to harmful levels. The kidneys are a pair of small organs that lie on either side of your spine at about waist level. They act as filters that keep your blood free of by-products and toxins