The kidneys filter water and toxins from the blood. The kidney filter about 120 to 152 quarts (113 to 144 liters) of blood to create 1 to 2 quarts (0.94 to 1.81) of urine every day, according to the National Institutes of Health (NIH).
They aren't just one big filtering sponge, though. Each kidney is a system of millions of tiny filters called nephrons. A nephron has two parts. The glomerulus is the first part of the filter. it strains blood cell and large molecules from the toxins and fluid. The tubule collects minerals that the body needs and puts them back into the bloodstream and filters out more toxins.