Don’t even think about trying to drink 8 glasses of water a day. This myth is even worse than what people believe about salt– at least there was some genuine, if flawed, science behind that. As for the idea that you need to drink all that Kevin Drum:
So I wondered where this myth came from. Answer: after undoubtedly prodigious research, Heinz Valtin of Dartmouth concluded a decade ago that it most likely came from a single paragraph in an obscure government report in 1945. Here it is:
A suitable allowance of water for adults is 2.5 liters daily in most instances. An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods.
Note two things: First, this is based on no actual research at all. It’s just a casual guess. Second, even if it’s true, it was misinterpreted. Everyone read the first sentence, which suggests that a 2000-calorie diet requires 2000 ml of water, or roughly 64 ounces. But they sailed right by the second sentence, which says that you get a lot of this automatically in the food you eat.
My wife is sure I don’t drink enough water– I’m going to politely refrain from explaining why here, but I seem to be getting along okay.