The brain structure which monitors his thirst and the need to drink more
water is Hypothalamus.
What is the Brain?
This organ is located in the head region of most organisms and serves as
the center of the nervous system.
It has some tissues in which hypothalamus is among which helps to
regulates body temperature, sleep, and appetite. Body temperature is
regulated by drinking water to prevent dehydration.
Read more about Hypothalamus here https://brainly.com/question/1022285
