9 Things You Need to Know About Water /Aqua Series 1

9 Things You Need to
Know About Water Is tap water safe? Can water go bad? And what about
those eight glasses a day?

by Leah Hennen

How much do you need?

For most people, not eight glasses. In 2002 Heinz Valtin, M.D., a kidney specialist and a professor emeritus at Dartmouth Medical School, spent nearly a year searching for evidence to back up the “eight glasses a day” dictum — and came up dry. “We didn’t find a single scientific report supporting the recommendation,” Valtin says.

So how much should you drink? “It depends on your size and activity level,” says Kristin Reimers, a registered dietitian and the associate director of the Center for Human Nutrition, in Omaha. You can tell if you’re getting enough by “looking at the color of your urine. A light lemon color means you’re well hydrated.” Even easier, just follow your thirst. “Our bodies do an excellent job of telling us when we need water,” Valtin says. “No need to force it.”

Do other beverages count?

Yes. Juice, milk, soda, and other liquids also help keep you hydrated. Even caffeinated beverages — long blamed for siphoning fluid from our bodies — seem to count. In a study conducted by the Center for Human Nutrition in 2000, subjects were given plain water or a combination of water and noncaffeinated soda, caffeinated soda, or coffee. No matter what they drank, they all stayed equally hydrated. Food is another ample source of liquid. Fruits and vegetables can be up to 95 percent water. All told, nutritionists estimate that we get two to four cups of water a day from food.

Is it possible to drink too much?

Possible, but not probable. Overhydration gets a lot of press, but it’s usually the result of marathon runners who “water load,” fraternity pledges who are force-fed liquids, or partyers who have taken Ecstasy, which can spur extreme thirst while suppressing signals of satiety. In a healthy, moderately active person, Heinz Valtin, M.D., a kidney specialist and a professor emeritus at Dartmouth Medical School, says, “the body’s water-balance system is so sensitive and accurate that water intoxication is highly unlikely.”

How safe is tap water?

Generally, it’s very safe. The U.S. has some of the cleanest drinking water in the world, and 9out of 10 public water systems meet federal health and safety standards, according to the Environmental Protection Agency (EPA). But that doesn’t mean you should be complacent. The quality of water varies depending on its source, treatment, and delivery system, as well as the plumbing it flows through, so you’d be wise to learn about what’s coming out of your tap, says Steven Patch, Ph.D., an authority on drinking-water safety and the director of the Environmental Quality Institute at the University of North Carolina in Asheville.

Patch suggests you read the water-quality report that your utility is required by law to release each year. Large providers are also required to post their reports online. Go to your water utility’s website or to the EPA’s site (www.epa.gov/safewater), which has links to scores of local water-quality reports.

Should you test your water?

Even if the report is reassuring, you might want to test your water for lead and arsenic, both of which are potentially harmful to your or your children’s health. Lead contamination can come from the plumbing in people’s homes (most often in houses built before 1986), so it isn’t accurately represented in water-quality reports. Arsenic is common in both well water and municipal water collected from wells, says Patch.

If you’re worried about unregulated contaminants — if there’s a factory upstream, for instance, or someone in your household has a weak immune system— you might want to test for microorganisms and other pollutants, says Erik Olson, the lead author of a study conducted by the Natural Resources Defense Council (NRDC), an advocacy group that tested the drinking water in 19 U.S. cities. If you find your water has contaminants, contact your local water carrier. (See Local Drinking Water Information Resources for companies that sell home test kits.)

Do you need to use a filter?

If you learn that your water has lead, arsenic, or other contaminants, yes. And if you’re concerned about your water quality for any reason, you should buy one. Filtering tap water is affordable and can remove everything from potentially dangerous chemicals and microbes to foul-tasting additives.

As for what kind is best, that depends on what you’re trying to filter out. If lead is a problem, shop for a filter certified by the nonprofit lab NSF International. If you’re concerned about microorganisms, buy an “absolute one-micron” filter, which is designed to strain out tiny germs, such as cryptosporidium. At the NSF site (www.nsf.org), you can search for certified water filters by the contaminant you’re targeting; click on “Consumer,” then “Drinking Water.”

Is bottled better?

Probably not. “Bottled water isn’t necessarily any better, purer, or safer than city tap water” and has some unique problems of its own, says Erik Olson, the author of NRDC study that tested more than 100 brands of bottled water over four years.

Though the U.S. Food and Drug Administration (FDA) has safety standards for bottled water similar to those the EPA sets for tap water, enforcement is often lacking. Similarly, most states have standards but not the resources to enforce them. In a third of bottled waters tested from 1997 to 2000, the NRDC found contaminants in levels that exceeded safety limits.

Despite the name or the picture on the label, there’s no guarantee that bottled water comes from a snow-dusted Alpine peak or a gurgling forest spring. Some groups, including the Consumers Union and the NRDC, estimate that at least a quarter of bottled water is simply tap water that may or may not receive additional treatment. If the label says, “From a municipal source” or “From a community water system,” it’s plain old tap water. If you prefer bottled water, choose a brand that belongs to the International Bottled Water Association (IBWA), an industry group that requires member companies — including Arrowhead, Dannon, Evian, Perrier, and Wal-Mart, and dozens more — to meet standards stricter than those of the federal government. Many IBWA members indicate that affiliation on their labels, or you can find a list of member companies at www.bottledwater.org. A mention of NSF International certification on the label is a good sign, too; NSF performs additional testing and inspects bottled-water plants annually.

Does temperature matter?

It makes no difference to your body whether you sip cold or warm beverages — both are equally well absorbed. In one study, scientists at the Federal University of Minas Gerais, in Brazil, gave cold, warm, and hot water to athletes before and during a strenuous workout. They found the temperature of the water had no effect on the subjects’ endurance or hydration levels.

But don’t use hot water straight from the tap, as it pulls more lead from pipes than cold does. And let the water run for at least 60 seconds, Steven Patch, Ph.D., an authority on drinking-water safety and the director of the Environmental Quality Institute at the University of North Carolina in Asheville, advises — lead levels are highest in water that’s been sitting in pipes.

Can water go bad?

Yes. Or, rather, things in it can. “Water is a great medium for bacteria,” Kristin Reimers, a registered dietitian and the associate director of the Center for Human Nutrition, in Omaha, says. So think twice about sipping from that half-drunk water bottle that’s been sitting on your nightstand since the day before yesterday. A study in the Canadian Journal of Public Health in 2002 found high levels of bacteria (in nearly two-thirds of cases, high enough to exceed safety limits) in water bottles that were reused without being sterilized. Wash your bottle in hot, soapy water or in a dishwasher, or buy a bottle meant for constant use that’s sturdy and easy to clean. Place bottled water in a cool, dark place, since heat and light can damage the containers. Treated and stored appropriately, water can do the job it’s designed for: keeping your body healthy.

© 2006 Time Inc. All rights reserved.