You may have heard that you should aim to drink eight 8-ounce glasses of water per day. How much you should actually drink is more individualized than you might think. The Institute of Medicine (IOM) currently recommends that men should drink at least 104 ounces of water per day, which is 13 cups. They say women should drink at least 72 ounces, which is 9 cups. Even still, the answer to exactly how much water you should drink isn’t so simple.