8 glasses of Water Myth

Yahoo! News: No Need to Guzzle All That Water, Expert Says

"[Dr. Heinz Valtin] hopes people will be relieved of the guilt of not getting enough water, and of the expense of buying bottled water to drink throughout the day."

I'm relieved about the former, yes, and the latter doesn't really affect me. Tap water is of extremely high purity, when compared to the developing world, and is fine. My rule of thumb: drink when I'm thirsty. Now if I could only master the rule of thumb of eating only when I'm hungry...