Adh controls how diluted or concentrated urine is by controlling the permeability of the:

ADH controls how diluted or concentrated urine is by controlling the permeability of the collecting ducts to reabsorption of water. The antiduretic hormone (ADH) is secreted by the hypothalamus and pitutary glands. When there is less water in the blood, secretion of ADH increases and hence increasing reabsorption of water. This also applies vice versa.