How does the hormone ADH help the kidneys regulate the water content of blood?

ADH is produced by the pituitary gland located in the brain. When the water content of blood is low, more ADH is released from the pituitary gland into the blood. When it reaches the kidneys, it causes the kidney tubules to absorb more water back into the blood. This makes the urine more concentrated. When there is too much water in the blood, less ADH is released causing the kidney tubules to absorb less water back into the blood. This makes the urine more dilute.