According to study, our body needs 8 glasses of liquid a day to stay hydrated. This means liquids like coffee, tea, soda, water, and liquids from our foods. We don't have to necessarily force our self to have 8 glasses of water or more per day because we can get liquids from other sources that we intake.
Our body is build pretty smart, it knows when we need to hydrate and that's when we feel THIRSTY. So drink when your thirsty.