Skip to content

    Health & Balance

    Font Size

    Water, Water, Everywhere

    How Much Water Do You Really Need to Drink?

    WebMD Feature

    April 16, 2001 -- You'd think we were suffering a nationwide drought, the way Americans go around clutching bottles of water these days. Forget American Express cards: The one thing many of us would never dream of leaving home without is our bottled water.

    By all rights, that should be good news. For years nutritionists have been warning us about the dangers of dehydration. Quaff at least eight 8-ounce glasses of water, the common wisdom goes, or you'll suffer the consequences: flagging energy, dry skin, lowered disease resistance, even constipation.

    Recommended Related to Mind, Body, Spirit

    10 Ways to Make Your New Year's Resolutions Stick

    By Sarah Mahoney There's an inevitable rhythm to January 1 at my house. I take down the tree, vacuum up pine needles, and start making my New Year's resolutions. The list usually looks like this: Lose weight. Swear off TV and saturated fat. Eat salads. Call Dad more. Write that novel. Floss. By midday I'm worn out, intermittently dozing in front of a football game and swiping my husband's million-calorie nachos. It's not that I totally lack discipline. It's just that I don't sufficiently appreciate...

    Read the 10 Ways to Make Your New Year's Resolutions Stick article > >

    And don't count the coffee, tea, or other caffeinated beverages you drink. Anything with caffeine, we've long been told, actually increases the risk of dehydration because it flushes water out of the system.

    Nor can you rely on thirst. By the time you're thirsty, you're well on your way to being dehydrated.

    There's only one problem with all these warnings. Almost none of them hold water. Here's why:

    Myth No. 1: We need to drink at least eight 8-ounce glasses of water a day

    Researchers aren't sure where this familiar advice came from, but most agree there's very little solid scientific evidence to support it. The average adult loses only about 1 liter of water a day through sweating and other bodily processes -- the equivalent of only four 8-ounce glasses. We typically get that much water just in the foods we eat. Drinking an additional eight tall glasses of H20 is probably more fluid than most of us need.

    What about older people? For years, experts have warned that elderly people are especially prone to dehydration because they lose their sense of thirst. But even this may be overstated, according to a report in the July 2000 Journal of Gerontology. Robert Lindeman, MD, professor emeritus of medicine at the University of New Mexico, surveyed fluid consumption among 833 elderly volunteers.

    "People who drank less than four glasses of water a day were no more likely to show signs of dehydration than those who drank six or more," says Lindeman. "We found absolutely no difference between those who drank a little and those who drank a lot when we looked at all the standard markers for dehydration."

    Of course, that doesn't mean you shouldn't drink plenty of water a day. In fact, there's at least one reason to think it's a very good idea. In a 1999 study published in The New England Journal of Medicine, researchers found that the more liquids men consumed, the lower their risk of bladder cancer. Men who drank more than 10 8-ounce servings of fluids had a 49% lower incidence of the disease than those who drank only half that much.

    Today on WebMD

    woman in yoga class
    6 health benefits of yoga.
    beautiful girl lying down of grass
    10 relaxation techniques to try.
    mature woman with glass of water
    Do you really need to drink 8 glasses of water a day?
    coffee beans in shape of mug
    Get the facts.
    Take your medication
    Hand appearing to hold the sun
    Hungover man
    Welcome mat and wellington boots
    Woman worn out on couch
    Happy and sad faces
    Fingertip with string tied in a bow
    laughing family