Nature's Perfect Beverage.

Your body can't function without it. It's essential for all metabolic processes. You can live 30 days without food, but only 4 to 10 days without it. It makes up about 70 percent of an athlete's body. Water--it's the liquid of life.

When you feel thirsty, you crave a tall, cold glass of water. But other than a cure for thirst, why do you need water?

"Water plays an important part in every bodily function," says Dr. Ann Grandjean, director of the International Center for Sports. "Without a doubt, it is the most important nutrient."

Water's many functions include:

* eliminating body heat through sweat

* carrying oxygen, carbohydrates, and fats to working muscles, then taking away wastes such as carbon dioxide and lactic acid

* flushing waste products from your body through urine

* lubricating your joints and connective tissues

* boosting your endurance during prolonged exercise

* curbing your appetite to potentially aid weight loss

* liquifying mucus when you have a cold (to make it blowable)

* diluting and dispersing medication and vitamins

* helping you digest food

What's on Tap?

A recent survey shows that three out of four people are concerned about the quality of their drinking water. According to Bronwyn O'Hara, an independent nutritional consultant, they should be. "Different water sources have different requirements for purity," says O'Hara. "With the chemicals and parasites that can accidentally get in, tap water can be a big question mark."

What substances should you be worried about? Cryptosporidium is the first culprit that comes to mind. It is a microscopic animal-borne parasite that can infect surface water supplies. Chlorine won't get rid of this bacteria. If infected, adults can expect about 10 days of digestion woes. Those with weak immune systems may suffer more severe symptoms.

Giardia, also known as tourista, is another little parasite that lodges in the intestinal tract and causes digestion complications. Lead is a problem too. It leaches into tap water through old plumbing or pipes repaired with lead solder, causing elevated blood pressure and even kidney damage. If you live in an agricultural community, pesticides can find their way into the drinking supply too.

While most people suffer no problems associated with tap water, O'Hara recommends, "If you're uneasy about the quality, get it tested." Call your local water company or health department for the name of an independent laboratory that can analyze water in your area.

A gimmick now plaguing concerned water consumers is the free water analysis being offered by water-filter salespeople. Don't rely on the results of this free analysis. It will probably recommend the kind of water filter being offered by your "helpful" salesperson.

If you're looking for a water filter to alleviate your tap water concerns, the market is saturated with about 600 of them. They can be divided into two categories based on the two basic methods of contaminant removal. The first method involves activated carbon filters that remove odor, color, taste, and contaminants such as chlorine by-products, copper, lead, mercury, herbicides, and pesticides. These are typically the least expensive filters (starting at just a few dollars).

Reverse-osmosis filters make up the second category. By forcing water through a membrane, the system removes most contaminants, including asbestos, copper, lead, mercury, and the most minute organisms, such as Cryptosporidium. Reverse-osmosis filters don't change water color or eliminate odors and may cost several hundred dollars.

Whether you want a simple filter such as those found in pour-through pitchers, or a more sophisticated device that taps directly into your water supply, do your homework. Make sure the system will filter out what you don't want in your water.

What's in That Bottle?

A nineteenth-century ad claimed bottled water to be "emetic, cathartic, and diuretic; good in both scrofulous and rheumatic affectations, likewise in venereal taints...." Maybe that's why Louis Pasteur had water bottled from the spa at Badoit, France, and shipped to him by the case. Or maybe that's why Peter the Great drank 21 glasses of water a day to prevent indelicate indigestion problems. Perhaps those curious water qualities are why George Washington tried to purchase a mineral springs in Saratoga County, New York. Whatever the case, by 1850, 7 million bottles of water were being produced annually from the Saratoga springs, establishing a market that enjoys the same popularity today as it did nearly a century and a half ago.

In those days people drank the bottled brands to cure a scrofula affliction (a swelling of the lymph glands in the neck). Today bottled water is consumed daily for different reasons. Some say they prefer the taste. Others turn to it as a calorie-free, caffeine-free, alcohol-free alternative. Bottled water is more available than ever before and is widely accepted as a beverage in its own right.

But how do you know if bottled water is really pure? Take a look at the types of bottled water now regulated for purity by the International Bottled Water Association (IBWA). Bottled water options include:

Artesian: Water from a well that taps a confined aquifer (a water-bearing underground layer of rock or sand).

Mineral Water: From a geologically and physically protected underground water source. It contains natural minerals and trace elements, but minerals cannot be added to this product.

Sparkling Water: Emerges from the source containing naturally occurring carbon dioxide. Soda water, seltzer, and tonic water are not sparkling waters.

Spring Water: Flows naturally from an underground source to the earth's surface. Must be collected only at the spring, or through a borehole tapping the underground source.

Well Water: Water from a hole bored, drilled, or otherwise constructed in the ground, that taps the water of an aquifer.

Purified Water: Produced by a process that removes chemical and microbiological contaminants by methods such as distillation, deionization, or reverse osmosis.

Drinking Water: Water sold in sanitary containers, containing no added sweeteners or chemical additives other than flavors, extracts, or essences comprising less than 1 percent by weight of the final product.

What if your favorite bottled water doesn't fall into one of the recognized categories? First, read the label to see what you're drinking. It could be plain old tap water with a fancy package. If the label doesn't give you the information you need, call the phone number listed on the package and ask about the company's water source.

Is one bottled water better than another? "Labeling and purity standards tell you what you're getting," says O'Hara. "After that, it's all a matter of personal preference."

Am I Drinking Enough?

According to Grandjean, water needs are strictly individual. "Although you hear the general 64-ounces-a-day rule, this isn't true for everyone. Each person has individual requirements."

Quintera says if you're having a sedentary day, 64 ounces (eight cups) may do. But if you're involved in strenuous exercise, you may need up to four liters.

"Don't pay attention to what others are drinking," Grandjean says. "Learn what your body requires."

Water comes from other sources too, says Grandjean. "Some people don't like the plain taste of water, but will consume a flavored beverage, such as a sports drink. Water is also contained in much of what we eat." In an average 2,000-calorie diet, this is where a typical person's ounces of water are coming from:

                           Percentage

Drinking Water                28
Soft Drinks                   18
Coffee/Tea                    15
Veggies                        8
Milk, Milk Products            7
Meats                          6
Grain Products                 5
Fruits                         3
Juices                         3
Other Foods                    5
Other Beverages                2

"The consequences of not getting adequate water can be dehydration," says Grandjean. "Symptoms include crankiness and lethargy in the early stages, followed by thirst, a lack of concentration, and finally dizziness and fainting. Normally we lose water through sweat, respiration, normal skin evaporation, and bodily wastes. When a person is involved in a strenuous activity, many of these processes speed up the loss, so it's important to hydrate adequately before the activity has begun, and frequently throughout the activity." The bottom line is that even if you're not thirsty, consume as much water as you lose. How do you determine how much you need? "Weigh yourself before and after your activity," recommends Grandjean. "Everyone has an individual need, and if you remember that a one-pound loss equals a half liter of water that must be replaced, this weigh-in, weigh-out process can be your personal formula."

"Don't cut back on water just because you're retaining fluids," warns Grandjean. "If the retention is from salt, increase your water consumption to flush the salt out of your body. If it's from hormones, there is not much you can do about it until your hormones swing into another cycle." The good thing about hormone swings is the water will go away.

So drink up. Go chug a few ounces and think about how that water is working in your body, then chug a few more for good measure. Don't let thirst be your only guide. By the time you are thirsty, you've already lost about 1 percent of your body's water. Use common sense. Start the habit, stick with it, and sip away, all day, every day!

Too Little Fluoride?

After she had drunk bottled water for more than three years, Joyce Malast's dentist found three baseline cavities. Upon questioning Malast's eating habits and brushing routines, the dentist decided she was doing fine in those areas. "Then he asked me if I drank bottled water, and when I said yes, he mentioned my cavities might have something to do with the lack of fluoride in it. He sent me to a periodontist, who asked the same questions and came up with the same reason for my tooth decay."

Fluoride is a mineral added to tap water and some bottled waters that decreases the rate of dental decay by refortifying the teeth. It does not rebuild enamel that is already destroyed. Instead, it strengthens weaker areas, making them more resistant to acid attacks.

But according to Dr. Paul A. Zitterbart, associate professor of oral biology at the Indiana University School of Dentistry, "the lack of fluoride in bottled water should be only a minor problem for adults. We get sufficient fluoride from a number of different sources, including soft drinks bottled from city water sources, food processed in city water, toothpaste, and mouth rinses. If your oral hygiene is good, your toothpaste contains fluoride, and you brush at least twice a day, there shouldn't be a problem created by the lack of fluoride in bottled water. That is, unless you have an underlying condition that makes you more susceptible to problems."

Joyce Malast had an underlying problem with gum disease. Her visits every three months to her dentist weren't enough to prevent the decay caused by a lack of fluoride. But she recognizes that she is an exception. "My dentist told me I'm more sensitive to things like a lack of fluoride in my drinking water because of my past dental problems." Joyce, who is a member of a bottled-water club at work, is the only member who's had problems.

Zitterbart urges avid bottled-water drinkers against jumping to conclusions about the lack of fluoride. "In most cases, it's not a problem. As a precautionary measure, however, let your dentist know that you drink mainly bottled water." And use toothpaste and mouthwash with fluoride, or ask your dentist about prescription fluoride supplement drops. If you prefer bottled water over tap water, there is no reason you should give up what you like best.

[H.sub.2]O on the Go

Here are some tips for taking water with you:

* Freeze some in the bottom of a bottle; then top it off with cold water when you're ready to go.

* Find a handy water carrier for your bike or belt, or use a water-bottle sling.

* Find a sports top and turn your water bottle into a squirt bottle.

* Always take along an extra water bottle in case your thirst exceeds your expectations.

Five Great Things to Do With Water Besides Drink It

Tone up--Doing a few laps in the pool is a great workout, and it triggers your brain to release those feel-good chemicals called endorphins.

Wake up--A cold shower, or a cold splash of water on your face, is an instant energizer.

Relax--Warm water, bubble bath, soft music, and dim lights are all it takes.

Play--How long has it been since you've gone wading or running through a sprinkler? A little bit of play can be a great stress buster.

Plant a tree--Then water it. It provides oxygen and shade as it grows. It's also a reminder that water is the great nourisher of life.

JJ Despain is a writer living in Indianapolis, Indiana.