Well, despite what you may have read or heard, the answer is probably no. It’s not that hydration isn’t important, it is. It’s just that your body does a remarkably good job of telling you when it needs water by making you thirsty. Your thirst is regulated in your brain by the hypothalamus, which also regulates body temperature, sleep, appetite and other important functions. Remember getting incredibly thirsty on a hot day when you were playing soccer or going on a hike? That’s your body at work noticing that you are dehydrated. Every time you eat, you also receive hydration through the foods you eat. So there’s no need to drink a specific amount of water per day – your body will let you know how much you need. However, there may be times when it is helpful to increase your fluid intake if you plan on exercising in a very warm environment, since you may experience excess fluid loss due to heavy perspiration.
You can learn more about how thirst works here.