(CBS) -- Though the human body depends on water to survive, many people don't drink enough of it.
Dr. David Dupree, a board-certified general surgeon in New York, says water makes up about 60 percent of your body weight. Every part of your body depends upon water to function properly.
"Think of it really as the fountain of youth," Dupree said. "It's the most basic thing, yet it runs the most complicated machine, our bodies. So, we're going to consume a lot. We have to maintain the machine to keep it moving."
However, your body expels water through everyday bodily functions, such as breathing and sweating. Conventional wisdom says to drink at least eight glasses of water per day, but that figure isn't actually based on solid scientific evidence.
Doctors say everyone's body is different. Dupree said, ""I think everybody has a different view on how much. Usually, the standard has been eight glasses of eight ounces of water a day. That allows us to sort of maintain our function."
The amount of water you should drink depends on many factors such as weight, gender, activity level and age. The National Academies of Sciences, Engineering, and Medicine report that the adequate amount for most men is about 15.5 cups. Women typically need 11.5 cups per day.
If you're not a big water drinker, nutritionists report that certain fruits and vegetables, such as watermelon, spinach and cucumbers, can help.