In early 2004, Coca-Cola launched its Dasani brand of bottled water in Britain. Dasani had already established itself as one of the most popular bottled waters in the United States.

Within weeks, however, Coke had a disaster in the making. The British press discovered that Dasani was nothing more than processed tap water and ran a series of indignant stories suggesting that consumers were being hoodwinked by the U.S. beverage giant.

Shortly afterward, a cancer-causing chemical -- bromate -- was discovered in Dasani bottles produced in Britain. The water was quickly withdrawn from store shelves and plans were canceled to market Dasani elsewhere in Europe, which to this day remains a Dasani-free zone.

"In the USA, it is the bottled-water market's second-most-popular drink," London's Independent newspaper observed. "Which goes to show we may have a special relationship with America, but there's a lot of clear blue water between us."

Ray Crockett, a spokesman for Coke, shrugged off the criticism. "There's no accounting for the British press," he said.

Be that as it may, most Americans are probably unaware that Dasani, like many bottled waters sold in the United States, doesn't originate from pristine mountain springs; it starts in the same pipes that run into people's kitchens.

Dasani undergoes a filtering process and, according to Coke, is "enhanced with minerals for a pure, fresh taste." But, in the end, it's still tap water.

"The consumer doesn't seem to care about source," said Gary Hemphill, managing director of New York's Beverage Marketing Corp., the leading compiler of statistics about the beverage industry. "As long as it tastes good."

As I reported in Wednesday's column, Americans spent an estimated $11 billion last year drinking 8.3 billion gallons of bottled water.

That means the average American consumed almost 28 gallons of Dasani, Aquafina, Evian or hundreds of other brands -- more than any other commercial beverage except soda. More than milk. More than coffee. More than beer.

Beverage Marketing Corp. estimates that the typical half-liter container of bottled water sells for about a dollar. That equates with a price of roughly $7.50 per gallon (although it's cheaper when bought by the case or in the five-gallon jugs found in many offices). Some of the more expensive brands can cost as much as $11 per gallon.

A gallon of regular unleaded gas was selling nationwide Thursday for an average $2.20, according to AAA.

"It's ridiculous," said Richard Wilk, a professor of anthropology at Indiana University who has studied the bottled-water industry. "Why do people spend so much to drink water from glaciers or from Iceland? What's the difference?"

Consumers typically say bottled water tastes better than tap water. But a series of well-publicized taste tests have repeatedly shown that tap water in municipalities nationwide compares favorably with most bottled waters.

Consumers also say they have health concerns about tap water. But, again, studies have repeatedly shown that tap water in most U.S. cities is as healthy as the bottled variety.

In San Francisco, city officials collected nearly 34,000 samples from the water supply in 2005 and ran more than 100,000 water-quality tests. "All compliance monitoring results met or exceeded federal and state drinking water regulations," the San Francisco Public Utilities Commission reported.

That same year, the commission held a blind taste test near the Ferry Building. The 300 participants were offered samples of two popular bottled-water brands (Crystal Geyser and Aquafina) and local tap water.

Half said they preferred the tap water. Twenty-five percent picked bottled water. And 25 percent said they couldn't tell the difference.

"I'd put our water up against bottled water any day," said Susan Leal, general manager of the commission.

The bottled-water industry downplays comparisons with far cheaper tap water, saying the boom in sales reflects consumers choosing bottled water over soda and other drinks, not as an alternative to what comes out of the faucet.

"Consumers are choosing bottled water in lieu of other packaged beverages," said Stephen Kay, spokesman for the International Bottled Water Association, the leading industry trade group. "They're looking for more water in their diet."

This sentiment was echoed by Jane Lazgin, a spokeswoman for Nestle Waters North America, which sells bottled water under the Perrier, Arrowhead and Poland Spring brands, among others.

"People want to avoid drinks that have calories, that have caffeine," she said. "This is the role that bottled water is playing in society today."

But John Sicher, the editor and publisher of an influential industry publication called Beverage Digest, said the trend away from soda is only part of the story.

"Consumers are drinking less tap water than they did 10 years ago," he observed. "One reason is the ubiquity of bottled water."

Not all bottled waters are the same. While many containers depict flowing rivers or mountain vistas, you have to read the label carefully to know whether the contents come from a spring or a faucet.

Under guidelines set by the Food and Drug Administration, spring water is water that flows naturally to the surface from an underground source. Mineral water also comes from an underground source but contains at least 250 parts per million dissolved solids such as minerals and trace elements.

If the label doesn't specify spring water or mineral water, it isn't.

The leading bottled water brand in the United States is PepsiCo's Aquafina, followed by Coke's Dasani. Each does more than $1 billion in annual sales, according to Beverage Marketing Corp.

Both Aquafina and Dasani, as well as many other bottled-water brands sold in stores and supermarkets, are what the FDA calls purified water. Purified water comes from the same municipal pipes that everyone else's water comes from.

The difference is that purified water undergoes any of a variety of filtration treatments to remove chlorine and most dissolved solids.

"It's municipal-source water that's been purified," explained Hemphill at Beverage Marketing Corp.

In other words, tap water.

"I guess that's how you could identify it."

The irony is that, while the packaging of purified water frequently evokes natural settings and often features the word "pure," it is distinct from ordinary tap water precisely because it has been run through sophisticated machinery.

It is, in other words, anything but natural. Industry representatives generally make no pretense of claiming that purified water is better for consumers than most tap water.

"We like to think that the reason people buy our bottled water is because it tastes great," said Coke's Crockett.

Ultimately, it's still water -- tasteless, odorless, colorless. But the beverage industry spent about $60 million in 2005 to convince people that they should drink their water from plastic bottles.

"There are subtle taste differences among the brands," insisted Kay at the International Bottled Water Association. "It depends on the consumer's palate."

On Sunday: Drinking Fiji.