Vasopressin(antidiuretic hormone, ADH) released from posterior pituitary increases reabsorption of water from distal and collecting tubules of the kidney, thus, helping in producing concentrated urine. If there is hyposecretion of vasopressin, then water will not be reabsorbed from the tubules and the urine thus produced will be diluted. This disorder is called diabetes insipidus which is characterized by producing dilute urine several times a day.