The answer to that question depends on your size, level of activity, and gender. Most adult men should drink about thirteen cups of liquid a day, which equals to approximately three liters and women should drink about nine cups of fluids, which is equal to approximately two point two liters. If they live an active lifestyle, then they may need to replace the fluids they have lost more often. If you are a larger person, take medicine that can make you dehydrate, are pregnant or nursing should add more water to their diets.
If you are a person who does live an active lifestyle you need to take in account also the environment when you figure just how much fluid you need. It the temperatures are very hot and will make you sweat then you will need more water. In addition, if you are active in a high altitude area or an endurance athlete then you may need more fluids.
When they suggest that you take in so much fluid a day it does not have to be plain water. You can drink flavored water, or add a slice of lemon, orange, or kiwi to a glass of water to give it a different taste. You can also eat your water by eating foods that are water enriched such as peaches, watermelon, cantaloupe, and strawberries. These types of foods are not only packed full of water but also contain potassium, which is the electrolyte that your body loses when you sweat.