I knew it! I've always thought it was a myth that you have to drink 8-10 glasses of water per day. This Urban Legends Reference Page proves the myth wrong.
People always say that you should drink 2 litres, 10 glasses, etc. but if my body doesn't send me enough signals that it requires water I'm not going to drink that much. Listen to your body I say, it knows how much water it needs to do the stuff it does. I'm tired of people nagging to drink masses of water, it just doesn't make sense.
The reference page also points out another very interesting fact:
"Additionally, the idea that one must specifically drink water because the diuretic effects of caffeinated drinks such as coffee, tea, and soda actually produce a net loss of fluid appears to be erroneous. The average person retains about half to two-thirds the amount of fluid taken in by consuming these types of beverages, and those who regularly consume caffeinated drinks retain even more"