Water is an essential requirement of the body in order to digest the food we eat and also so as to safeguard the body from getting dehydrated, and to keep the body functional. But, how much water you need to drink is not clear. There are many confusing opinions regarding how much water one should drink per day. The health authorities used to recommend eight 8-ounce glasses of water per day as the standard requirement. That means you need to drink two liters of water per day. But that depends on other circumstances also.