Ask the Expert: How Much Water Should I Be Drinking?

A urologist settles the great hydration debate.

You’ve probably heard a million things when it comes to hydration. Drink eight glasses of water per day. Have a glass with every meal. Just sip whenever you’re thirsty. Which of these is actually right? We asked Shaun Wason, a urologist at Boston Medical Center and an assistant professor at Boston University School of Medicine.

Question: How much water should I be drinking?

Answer: More than just when you’re thirsty, and more than you probably are. And eight glasses is likely not enough.

The details: Eight glasses seriously isn’t enough? It depends on the person, Wason says, because every individual is different in terms of weight, exercise, and other daily habits.

Still, he says a good guideline comes from the Food and Nutrition Board: 3.7 liters a day for the average male, and 2.7 liters for females. That translates to 15 and 11 glasses, respectively.

One important caveat: Those figures represent total fluid intake, not just water. Eighty percent of that number will come from liquids, and the remaining 20 percent comes from water-rich foods, such as fruits and vegetables. Even when it comes to fluids, Wason says you don’t have to drink plain H2O exclusively.

“Ideally, the majority of that should be water, but pretty much any fluid will count,” Wason says. “So even alcohol, even caffeine, decaffeinated tea, sparkling beverages, that will all count toward your daily intake.”

That isn’t to say that you get to toss your Camelback and rely solely on Dunkin’ for your hydration—water prevents constipation, carries nutrients to cells, lubricates all the mucous membranes in the body, and potentially helps you eat less—but Wason admits it would be “somewhat unreasonable” to insist all your fluid intake come from water.

The bottom line: Drink more water.

Wason recommends carrying a liter water bottle around with you and downing a bottle before and after lunch. If you need a little more help, there’s an app for that—lots of them, in fact. Options include Waterlogged, iHydrate, Plant Nanny, and many others.

“If you have [water] on the desk or where you’re working, you’re more apt to take little sips throughout the day,” Wason says. (This is your reminder to take a sip.)

If you’re still unsure about whether you’re drinking enough, a good gauge is the color of your urine. If it’s colorless or a very pale yellow, you’re doing a good job. The darker it is, the more dehydrated you are.

Bottoms up.