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Doctors Say Drinking Eight Glasses Of Water Per Day Is Unnecessary

BOSTON (CBS) -- You may often hear you should drink at least eight glasses of water a day to stay hydrated and healthy, but as Dr. Mallika Marshall reports, you can probably flush that number down the toilet.

Tom Schalk drinks a lot of water. "I'm trying to hydrate before we get to the gym, then at the gym, then after the gym," he explains. Tom now guzzles 6 to 8 bottles a day. "I feel like I'm doing something good for myself," he adds.

So how much does the body need? A new article published in the Harvard Health Letter recommends 30 to 50 ounces a day. Fluids carry nutrients to your cells, push bacteria from your bladder, and prevent dehydration.

Dr. Sharmeela Saha of the University Hospitals Case Medical Center says you shouldn't think about your fluid intake in terms of glasses of water.

"Sometimes people say about the 8 glasses of water a day," says Dr. Saha. "It's really about fluids in general. It doesn't necessarily have to be water. And I think that 8 might not be the true target. I think it might be better to do more like the 30 to 50 ounces a day."

Doctors say getting enough water is not just about what you drink, but what you eat, too.

"Lettuce, spinach, fruits in general, soups," explains Dr. Saha. "Those are all things that are going to have a lot of water in them as well."

Martha Hileire relies on fruit like watermelon and cantaloupe for her water intake because sometimes she doesn't drink enough.

"It's not like you don't know you have to drink the water," says Martha, "But you're so busy you forget to drink the water."

Doctors say you should drink even more fluids when you sweat, especially during these hot summer months. Women who are pregnant or breast feeding also need more fluids, on average, and for people with congestive heart failure or kidney disease, too much fluid can be harmful.

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