Do you need to drink 8 cups of water per day? Dr Chris Van Tulleken suggests there might not be a need for drinking an excessive amount of water per day, regardless of what we have been told in the past. Earlier this year sports scientists got together in Australia and performed tests on athletes to test hydration levels. The tests were done to check performance after dehydration had occurred and there was no difference between athletes that were fully hydrated and those that were not.
Of course I believe that water is important and that if you are exercising you should drink enough for your own body. The outcome of the article which is from the BBC online is that drinking more water won't necessarily hydrate you as you pee it out. You get water from foods and drinks too. Dr Chris Van Tulleken states at the end, saying that you should drink more water than your body asks for is like saying that you should consciously breathe more often than you feel like because if a little oxygen is good for you then more must be better.
My advice, have enough water for your body type and if you are exercising drink a little bit more.