Drink some water, then drink some more

That ever-present bottle of water has become a fixture of modern life not just among athletes but in business meetings, on mass transit, in shopping malls and beach blankets.

But how much water, really, is necessary for health and hydration?

In fact, the numbers may sound daunting: If you're a man who's 19 or older, the Institute of Medicine thinks you should consume the equivalent of about 16 eight-ounce glasses of liquid a day. For women that age who aren't pregnant or lactating, the number is 11.

That's far beyond the long-held advice to drink eight glasses of water a day. But no need to work yourself into a sweat. The truth is that staying properly hydrated is not as tough as you might think.

For one thing, focus on the word "equivalent" in the recommendation from the institute, an arm of the National Academy of Sciences. Then, keep in mind other suggestions from health experts, such as:

1. Remember that there's water in food.

About 20 percent of our recommended daily allowance of water comes from food, according to the institute. That means you don't have to go looking for a way to drink all those glassfuls. Fruits and vegetables can be great sources of water in your diet.

2. Even soda counts.

When it comes to water consumption, "soda counts, juice counts and coffee counts," said registered dietitian Leah Holbrook, a clinical instructor of family medicine at Stony Brook University. But these drinks can be heavy in caffeine, sugar or both. A 20-ounce plastic bottle of sweetened soda can contain the equivalent of 17 packets of sugar, she said, and two cups of juice can contain the equivalent of 14 packets.

Holbrook recommends other options that won't get you wired up or add extra pounds, such as seltzer water and unsweetened iced tea. For a little flavor, consider adding an orange or lemon slice to ice water.

3. Don't rely on thirst.

"It's not a good indicator of whether you're getting dehydrated," said Nancy Copperman, a registered dietitian and director of public health initiatives with the North Shore-Long Island Jewish Health System. "You can get dehydrated and not get thirsty."

For instance, chugging an ice-cold beer after doing some yard work might sound appealing, but alcoholic beverages seem to suck water out of the body, making you even more dehydrated. One option might be to alternate beer (or wine or liquor) with glasses of water, Holbrook said.

4. Drink more if it's hot or you're working out.

This may sound like obvious advice, but sometimes "people forget to drink the amount of water they need while they're exercising or being physically active," Copperman said. Swimming can be especially risky because you might feel like you don't need to drink anything because you're wet, she said.

5. Beware of sports drinks unless you're exercising.

Sports drinks such as Gatorade and Powerade can pack a lot of calories and aren't necessary unless you're exercising intensely, Copperman said.

6. Don't fret about overdoing water.

In fact, a potentially fatal medical condition, called water intoxication, can occur after massive liquid consumption. But it's rare, and you'd have to drink extreme amounts in a short period of time. But normal amounts of water -- such as those suggested by the institute -- should cause no problems. Do remember, though, that chilled water can cause cramping if you're exercising.

7. Watch the end result.

Water goes in, and water goes out. Monitor your hydration level by keeping an eye on your urine, Holbrook said. "Your urine should be a pale yellow color," she said. "That's a good indication that you're getting enough fluid. But remember that some vitamins can cause the urine to be bright yellow."