May 9, 2005 - It started with Perrier. Somehow, a French company convinced people it's cool to buy bottled water. Today, Evian has surpassed Perrier in sales and now it's the chic French water of choice. Why? It costs about 5 bucks a gallon! Why do people pay so much for something they can get virtually free?

If they're not buying Evian, they buy Aquafina and Dasani and the dozens of new brands that are jumping into this billion-dollar business, including bizarre ones like Venus, the Water for Women, and Trump Ice, with "The Donald" scowling on the label. I'd have to be very thirsty to buy that.

Many people say they buy bottled waters because they taste better. We spoke with people in New York City, asking them why they liked bottled better than tap water.

"I drink Dasani. It tastes good, it tastes crisp, like -- natural," one girl said.

"I think tap water kind of tastes like sewer," said another.

People also say they drink bottled water because they believe it's safer than tap water.

One man told me he's the only one "who's brave enough" to drink tap water at home. His family's afraid to drink tap water because of germs, he said.

At recent Earth Day celebrations, a lot of people told us they believe tap water is unhealthy. "As a parent I feel more comfortable giving her bottled water," one father told us.

Bottled water, we were told, is cleaner, safer, healthier.

Watching bottled water ads, you'd think that tap water might not be healthy. But it's not true.

"20/20" took five bottles of national brands of bottled water and a sample of tap water from a drinking fountain in the middle of New York City and sent them to microbiologist Aaron Margolin of the University of New Hampshire to test for bacteria that can make you sick, like e. coli.

"There was actually no difference between the New York City tap water and the bottled waters that we evaluated," he said.

Many scientists have run tests like that and have consistently found that tap water is as good for you as bottled waters that cost 500 times more.

Even Yale University School of Medicine's Dr. Stephen Edberg, the person whom the International Bottled Water Association told "20/20" to talk to, agreed that bottled water is no better for you. "No, I wouldn't argue it's safer or not safer."

"Healthy is a funny definition," he said.

"I wouldn't say it's healthier than tap water. I mean, they both provide water," Edberg added.

Maybe a taste difference justifies spending more money?

"I can definitely taste the difference between like a Fiji water and an Evian and a Poland Spring," one woman said. Many brands -- Aquafina, Deer Park and Dasani -- had loyal fans.

The labels of the bottled waters do suggest they're special. Some show mountains or polar bears or glaciers. You have to look at the fine print to find out Everest Water is not from Mount Everest. It's from Corpus Christi, Texas. Glacier Clear Water is not from a glacier in Alaska. Its source is tap water from Greeneville, Tenn.

Big-selling Dasani and Aquafina are also just reprocessed tap water from cities around the country. One of Aquafina's sources is the Detroit River! At least the popular French water, Evian, does come from France.

But does that make it taste better?

That's what people say, but is it true?

We ran a taste test, offering people New York City tap water and five other bottled waters, Evian, the top-selling bottled water Aquafina, Poland Spring, Iceland Spring (which comes all the way from Iceland), and American Fare, a discount brand from Kmart, which sells for less than half the price of Evian.

Would people be able to tell the difference when they didn't know what they were drinking? Would they still prefer their favorites?

Many who took our taste test were bottled water drinkers. They pay for it, they say, because tap water just doesn't taste as good.

It tastes flat and flavorless, they said.

Would the taste test show that?

We asked people to rate the waters as bad, average or great. Lots of people said one of the waters was particularly bad. Was that the tap water? No. Tap water did pretty well. Even people who said they don't like it, liked it on the blind test.

The "20/20" taste test was just one unscientific test, but lots of tests keep finding that people like tap water.

I suspect many people who buy the fancy waters are getting suckered by the ads or the labels.

In our test of bottled waters, Kmart's American Fare -- the cheapest brand -- won. Big-seller Aquafina came in second.

Iceland Spring tied the ordinary tap water for third place. Fifth place went to Poland Spring, and in last place, by far, with almost half the testers saying it tasted bad, was the most expensive water -- the fancy French stuff, Evian.

"It tasted like toilet water," one man said.

Evian had no comment about that review.

Bottom line, if you buy bottled water because you think it's healthier than tap, test after test shows no evidence of that. And if you buy fancy brands because you think they taste better, you're probably just buying the hype.