In 1977 the American public its first television commercial for bottled water. Orson Welles crooned about a place in the south of France where "there is a spring, and its name is Perrier," and the response was feverish. American sales of Perrier up more than 3,000 percent from 1976 to 1979.

"I remember thousands of us in Perrier T-shirts in the 1979 marathon," said Johanna Raymond, a New Yorker. "Perrier was the coolest thing then. It more than water."

Since Perrier's introduction, the American market for bottled water has from almost nothing into the world's largest. The Beverage Marketing Corporation, the industry's main research group, that Americans spent more than $9 billion on bottled water in 2004 (the latest year for which complete figures are available) and that it has growing at almost 10 percent a year for the previous 10 years, something almost unheard of in food marketing. "There appears to be no limit," said Gary Hemphill, a Perrier analyst, "to how thirsty Americans ."

Nor to the ways the bottlers water. The forests of France and the hills of Maine quickly evolved into Icelandic glaciers and Pacific aquifers, and for the 40 percent of bottled waters that are made from municipal tap water, minerals are added to a better, more "watery" taste. Now, the selling point is often not the water, but what's in it: the flavorings, the vitamins, the stimulants and other "enhancements" that are to be an improvement on simple H2O.

Industry analysts consumers have embraced bottled water as a healthy alternative to soda, still the most popular beverage in the country. But when is water no longer water? In the nation's refrigerator cases, we rifle through bottles of vitamin water, energy water, fitness water and fruit water, all of them variations on water, flavoring, coloring and often sweetener.

For years Gatorade was alone in the field of "enhanced" waters, water with additives that may have specific health benefits, including vitamins and minerals like electrolytes and salts. But no longer. In 2004 Pepsi $256 million worth of Propel Fitness Water, which it introduced in 2000. "I to drink way too much soda, but now I five or six Propels a day, usually melon and kiwi-strawberry," said Jerry Fox, an environmental consultant in Girdwood, Alaska.

If it is artificially flavored with passion fruit, sweetened with Splenda and colored with yellow dye No. 5, is it still water? When I the ingredients of a popular flavored water to Marion Nestle, a professor of nutrition at New York University, she said the beverage was technically indistinguishable from diet soda, except for the carbonation. "If it sweetened, it might as well be soda, nutritionally speaking," she said. "It's not really water."

Nearly 200 new waters and "water beverages" introduced last year, a virtual ocean infused with such diverse enhancements as the melt-offs of glaciers and icebergs, appetite suppressants, black truffles, caffeine, ginseng, vitamins, "superoxygen," cucumbers and even Sylvester Stallone. (Sly Pure Glacial Water, from the "10,000-year-old Carbon Glacier on the north face of Mount Rainier," will be released next month.) Zodiac's Bio-2 water to have changed the molecular structure of water in ways that increase an athlete's stamina. Icelandic Glacial is a "superpremium" water from a spring shielded from pollution "by an impenetrable barrier of lava rock." (The Food and Drug Administration does not regulate terms like "enhanced" and "flavored" or claims like "crystalline" and "vibrational." But water labeled spring, artesian or mineral must bottled directly at the source.)