Drinking Water

Thomas Andrews: The pumps will buy you time, but minutes only. From this moment on, no matter what we do, Titanic will founder.

Thomas Andrews: She is made of iron, sir. I assure you, she can. And she will.

The movie Titanic was an epic story of love, disaster, and too much water. Water indeed is unparalleled in its ability to both give life and to destroy it. Today, however, we’ll try to talk about its more positive aspects and specifically, how much is just the right amount for us.

Quick show of hands: how much water should a person drink each day? Whoa! That’s a lot of hands. Apparently everyone knows the answer to this question! You there, in the front. What’s your answer? “Eight glasses a day!” Ooo… good. That’s almost right. Let me splain…

The origins of the “eight glasses a day” rule are murky and it’s not the only water rule-of-thumb. My personal favorite is “one ounce of water per pound of body weight per day.” Oh really! Let’s see how this one plays out. I’m around 207 pounds right now, so that’s 207 ounces per day, or nearly twenty-six glasses. Twenty-six! That’s like taking a one ounce shot, every seven minutes, for twenty four straight hours.

If we all drank that much water the economy would come to a screeching halt. No one could get anything done, being stuck in the bathroom twenty-four/seven. (Might be a good time to invest in wastewater treatment facilities, though.)

So I did a bit of searching and came across a study by Heinz Valtin published in the American Journal of Physiology-Regulatory Integrative and Comparative Physiology in 2002. It was entitled “Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8″? He searched high and low for the origins of this strangely universal recommendation. About the closest he came was a comment found in 1945 from the National Research Council:

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.

What I find most fascinating is that we always assume “water” means “glasses of water”. But take another look at that last sentence. Once the dihydrogen monoxide (yes, that’s good ol’ H₂O) goes down your esophagus, your body doesn’t know or even care where it actually came from. Sure, drinking bottle after bottle of water is easy and (mostly) painless. But there’s water in coffee, in tea, and in diet sodas, too. There’s water in carrots, and apples, and in cheese. There’s water in bread, in lunch meat, and chocolate cake. Ironically there’s still small amounts of water in dehydrated foods.

So how much water should you have? Well, the answer is: enough. It’s different if you’re active or sedentary. It’s different if you’re working at a desk or under a 97 degree sun all day. It’s different if you’re young or old. Like so many things in life, there isn’t a “one size fits all” amount, in spite of how desperately we cling to such beliefs.

We actually have a pretty good built-in mechanism for keeping ourselves properly hydrated. Just don’t ignore it. Like right now. My body is saying, “More diet cola with lime! More diet cola with lime.”

I must comply.

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