There’s no evidence to back that up. The Institute of Medicine recommends that men get about 125 ounces of water daily and that women get 91 ounces, but that includes water from all foods and beverages. Most people get enough hydration unless they’re exposed to heat stress or they’re very active for a long time.
There are many different opinions on how much water we should be drinking every day. The health authorities commonly recommend eight 8-ounce glasses, which equals about 2 liters, or half a gallon. This is called the 8×8 rule and is very easy to remember.
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.