While many in developed countries thirst for safety, cleanliness, taste and social cachet when they buy bottled water, more than 1 billion of the world's poorest lack access to clean drinking water, bottled or not.

And in developed countries, bottled water may be scrutinized using lower standards than plain tap water, the report said.

The environmental impact can start at the source, where some local streams and underground aquifers become depleted when there is "excessive withdrawal" for bottled water, according to the report.

In addition to the energy cost of producing, bottling, packaging, storing and shipping bottled water, there is also the environmental cost of the millions of tonnes of oil-derived plastic needed to make the bottles.

"The beverage industry benefits the most from our bottled water obsession," Ling said in a statement. "But this does nothing for the staggering number of the world's poor who see safe drinking water as at best a luxury and at worst an unattainable goal."

Worldwatch estimated 35 to 50 percent of urban dwellers in Africa and Asia lack adequate access to safe potable water.

Most water is bottled in polyethylene terephthalate, or PET, which requires less energy to recycle and does not release chlorine into the atmosphere when burned. But recycling rates have declined: about 23.1 percent of PET water bottles were recycled in the United States in 2005, compared with 39.7 percent 10 years earlier, the report said.

Bottled water costs from 240 to 10,000 times as much as water straight from the tap. In dollars, that means such water sold in most industrialized countries costs US$500 to $1,000 per 1 cubic metre (35.3 cu ft), compared with 50 cents per cubic metre in California, where the quality of tap water is high.

World consumption of bottled water more than doubled between 1997 and 2005, with the United States being the largest consumer. US residents drank nearly 6.3 billion gallons (28.6 billion litres) in 2005, the report found.