Do you really need to drink eight glasses of water a day?

BY: Nicole Gregory

No, according to Dan Negoianu, M.D., and Stanley Goldfarb, M.D., of the University of Pennsylvania School of Medicine, who recently looked at all the research on water intake and found no basis for the claim that drinking eight glasses of water a day has health benefits. “There is this intuitive sense that drinking a lot of water flushes out your system,” says Dr. Goldfarb, “but it’s not true.” It’s the job of the kidneys to remove toxins from the body, he explains, and drinking more water does not improve that function. The researchers also found no evidence that drinking water relieves headaches or makes your skin look better.

But there’s no harm in drinking eight glasses of water, either. “Nothing terrible is going to happen if you drink a lot of water,” Dr. Goldfarb says. Daily fluid intake -- from water, other beverages and foods -- is necessary for survival, though research offers no guidelines on how much you should drink, and individual needs vary, depending on your activity level, body size, age and the temperature of the environment. (Also, contrary to popular belief, the diuretic effects of coffee and tea are negligible, Dr. Goldfarb adds, so they actually will help you stay hydrated.) So how much fluid should you drink? Dr. Goldfarb recommends using your thirst as a guide.