The purpose of the two kidneys is to filter the water in your blood as the blood passes through the kidneys. About 4 gallons of water are filtered every day but only around 3 pints are pulled out as urine.
Alcohol and sugar are the most damaging to the kidney since they kill kidney cells and weaken the kidney function.
Water is the major way the body keeps toxins from accumulating in the body and skin. You need to drink plenty of clean water daily so the kidneys can remove toxins and excess nutrients, vitamins, and minerals from the blood.