How much water do we need to drink in a day? Once again, conventional wisdom is incorrect or at least in this matter unproven. There is no scientific basis that we need to drink at least eight 8 oz glasses of water in a day. There is no science behind this claim. How this recommendation even got started is a mystery to me. Probably from a bottled water company as a way to push sales.

http://www.medpagetoday.com/PublicHealthPolicy/PublicHealth/27519