Dear student,
ADH (Anti-diuretic Hormone) serves an essential part in osmoregulation to control the body's urine formation and water and electrolyte balance.
When blood becomes more concentrated, Hypothalamus stimulates the release of ADH. The ADH regulates distal convoluted tubules' permeability and collects ducts to water by opening the water channel to increase water reabsorption there.
When the blood becomes as dilute as required, the secretion of ADH is inhibited.
Regards