How much water should you really drink?

NEW YORK - With the popularity of trendy water bottles and the simple fact that bottled water is so readily available, many Americans might be overdoing it just a tad in the hydration department.

"Our kidneys are really good at holding onto salts and water," says Dr. Kelly Anne Hyndman, a kidney function researcher at the University of Alabama at Birmingham. "For most people, they just drink because they psychologically think they need to drink when in reality you only need to drink to replenish what you lose in the day through sweat, through breathing and through your urine."

Drinking more water than you should doesn't mean you'll be more healthy either.

"There's this idea that it flushes out the toxins in your body and things like that," adds Hyndman. "There's probably some level of truth to that, but I think people are just taking it to the extreme." 

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So how much water should one drink? We've all been taught that eight 8-ounce cups of water per day is the goal to strive for, but many believe it's a blanket approach. According to Hyndman, there's no set number per person but instead factors to take into consideration.

"It depends on lots of factors--what you're eating, your activity level, what kind of climate you live in. Right. If you're in a drier, arid environment, you're going to have to replace more water because you're sweating more," said Hyndman.

She says a good rule of thumb is to simply drink when you're thirsty.