It’s summer, the hottest time of year, and everywhere you turn you’re hearing about the importance of drinking enough water and fluids.

But how much should we be drinking?  The daily water intake recommendations by the Food and Nutrition Board of the National Academies of Sciences are 13 cups (3.7 liters or about 125 ounces)daily for men, and 10 cups (2.7 liters or about 91 ounces) for women.  These are very general though, as a single recommendation is impossible.  A lot depends on factors like these:

Weight. If you weight more, you usually need to drink more, but it’s not a linear progression.  That is, a 200-lb. person doesn’t need twice the fluid of a 100-lb. person.  The smaller person is more vulnerable to dehydration and overheating because they have a high “surface-to-volume ratio,” the same reason a small child is more vulnerable to overheating.

Gender. Men tend to need more fluid than women.  They tend to weigh more but also have more muscle, which is metabolically active and requires more water to stay hydrated and function properly.

Activity level. But the more active you are in any season, the more you sweat and thus need to rehydrate.

It doesn’t all have to be water and the IOM is clear that all beverages , including coffee, tea, milk, and even juice, so getting those 9 to 13 cups is easier than you think. Liquids aren’t the only place to get water.  You can easily amp up your take from food if you include plenty of high-water fruits and veggies, and there are real advantages to doing this:

• Flavor! Chilled summer fruits and vegetables are taste powerhouses.
• Rehydration nutrition: high-water fruits and veggies are loaded with hydrating nutrients like potassium and magnesium. Count milk in here, too.

For highest water content, go for fresh versiuons.  Here’s a list of some of the most common high-water fruits and vegetables (by % weight):

Many are more than 90% water, so they really contribute to your total fluid intake for the day.  Plus, they do what a glass of water simply can’t: help you get enough fruits and vegetables for a healthy diet.

Personal fave: watermelon.  I love this stuff.  I have loved watermelon since I was a kid and waited for it to come into season so I could gorge myself on it.  Even now, when I come home on a steamy, sweltering day there is absolutely nothing better to cool me down and get my taste buds dancing than a huge chunk of ice-cold watermelon.  I’m hardcore, too.  I cut off only the outer skin because I love the white part of the rind as well.  It’s not as sweet but that’s OK and it’s still good, kind of like a semi-sweet cucumber.

MORE: Can you be a health-freak AND a smoker?  Get my take in this New York Post article here.