NEW YORK (CBSNewYork) — Amid the dog days of summer, staying hydrated is especially important.

We often hear eight glasses of water a day is the magic number, but some doctors say that’s not necessarily true.

Tom Schalk drinks a lot of water.

“I’m trying to hydrate before we get to the gym, then hydrate at the gym, then hydrate after the gym,” he said.

He guzzles six to eight bottles of water a day.

“I feel like I’m doing something good for myself,” Schalk said.

So, how much does the body need?

As CBS2’s Weijia Jiang reported, 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.

“Sometimes people will say about the eight glasses of water a day. It’s really more about fluids in general,” said Dr. Sharmeela Saha, with University Hospitals Case Medical Center. “I think that eight might not be the true target, it might be better to do more like the 30 to 50 ounces.”

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

“Lettuce, spinach, fruits in general, soups — those are all things that are going to have a lot of water in them as well,” said Dr. Saha.

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, but you’re so busy you forget you have to drink the water,” she said.

Doctors suggest you drink even more fluids when you sweat, especially during the summer months. And women who are pregnant or breast feeding also need more fluids.