Forget eight glasses a day. Have you had your 28 gallons a year?

This is not about basic hydration. This is how much bottled water -- the stuff that costs more per gallon than the high-octane stuff you complain about at the pump -- the typical American consumed last year.

Yet, even with all the recent attention to the sourcing and ecological impact of this ubiquitous beverage, most Americans know little about the $11 billion worth of water they drink a year, never mind how or why to evaluate it.

They should, say experts who compare bottled water to wine.

"We usually think it's all the same, but it isn't because of trace elements, minerals, packaging," says Arthur von Wiesenberger, a consultant who might be to water what Robert Parker is to wine.

"Water is an amazing thing," he says. "It will reach out and touch something."

The something that it touches will give it a distinct taste and even "mouthfeel," in the parlance of water tasters.

Potassium, for example, can give water a sweet taste. Silica can impart silkiness. Calcium can give the water a lactic taste some people find refreshing. Others enjoy the cleansing quality of water with a high sodium content.

"Bottled water is the next wine," says bottled water expert Michael Mascha, the founder of finewaters.com, a site dedicated to cataloging and evaluating bottled waters from around the world.

"People are starting to pay attention to where water is coming from. In a general sense, bottled water is making the transition from a commodity product to one with terroir ," he says.

Long a staple of European tables, bottled water was popular in the U.S. during the early 20th century, but vanished during the Great Depression. It resurfaced during the 1970s, when Perrier was photographed in the hands of glitterati.

During the past five years, consumption surged 59 percent, making it America's favorite beverage after soda. In 2006, Americans quaffed 8.3 billion gallons of bottled water.

In the United States, consumers can now pick from about 350 varieties of bottled water, ranging from purified tap water (such as Coca-Cola Co.'s Dasani and Pepsi's Aquafina), to waters bottled from particular sources.

Sourced waters can come from springs (such as the sparkling San Pellegrino or the still Evian), underground reservoirs called aquifers (such as Fiji and Voss), or even from glaciers or harvested rainfall.

Each source, say connoisseurs, has its own fingerprint.

In Philadelphia, Water Works Restaurant and Lounge, which opened last year, stocks nearly two dozen waters from around the world and caters to a regular crowd of newly minted connoisseurs willing to pay up to $55 a bottle.

"We have several regular customers who come in and have to have their water and it's chilled to a different degree," says the restaurant's guest services coordinator Vera Masi.

"Some people will taste it and actually say 'This is woodsy' or 'This is crisp,' " she says. But, she adds, many other customers use a less sophisticated screen: packaging.

The restaurant's most expensive water, the $55 Bling H20, comes in a vessel encrusted with Swarovski rhinestones. "I guarantee you that every single person who orders the Bling takes the bottle home with them," she says.