Walk through the beverage aisle of a grocery store and it is hard to miss the seemingly endless supply of bottled water on the shelves.

　　Sparkling, fizzy, mineral, distilled, purified - bottled water comes in many forms as well as flavors such as lemon, black cherry, raspberry, kiwi and strawberry.

　　Manufacturers sold more than US.7 billion worth of bottled water in the United States last year, an increase of 12.3 percent from 2001, according to the Beverage Marketing Corporation.

　　Last year, the average US consumer drank 21 gallons (79.5 liters) of bottled water, about 11 percent more than in 2001, the marketingsgroupssays.

　　Some environmental groups and consumers are concerned both about bottled water's price and effect on the world's water supply.

　　The US Natural Resources Defense Council estimates that bottled water is 240 times to 10,000 times more expensive than tap water. While consumers may pay a few dollars for every thousand gallons of tap water, they can pay almost US per 3.8 liters of some brands of bottled water.

　　The organization also says the booming bottled water industry could be draining aquifers and other water resources, contributing to pollution and producing energy inefficiencies.

　　There's "an immense waste of energy and plastic and resources if you consider the number of bottles that are made and transported and disposed of," says Erik Olson, a lawyer for the group.

　　Researchers are warning that if water use continues to increase at the current rate, the world will be in very short supply in 22 years.

　　J. Darius Bikoff, president and chief executive of Energy Brands Inc, says the water it markets is a tiny fraction of total water usage.

　　"I don't think if you look at every gallon of water that it has a big impact on total global production by nature," says Bikoff, whose company makes the Vitamin Water and Smart Water brands.

　　Lester Brown, head of the Earth Policy Research Institute, agrees that bottled water companies are not a factor in the depletion of water resources. He cites information from the United Nations' Food and Agriculture Organization.

　　A consumer typically drinks a little more than a gallon of water every day. But food companies and farms worldwide use up to 1,300 gallons every day to produce food, the UN agency says. That means 70 percent of total water withdrawals are for producing food.

　　"If we're looking at supply problems, it's not likely to have that much of an effect," Brown says of bottled water production.

　　He notes that some countries must rely on bottled water to drink because their tap water is too polluted.