Despite perceptions that it's healthier, there is little difference between bottled water and tap water - apart from cost - selling to up to 1,000 times the price, according to the World Wildlife Fund (WWF).

Bottled water is the fastest growing beverage industry in the world, worth up to $22 billion a year, according to the fund. A study commissioned by the WWF found the "bottled water market is partly fueled by concerns over the safety of municipal water and by the marketing of many brands which portray them as being healthier than tap water."

The study, conducted by University of Geneva researcher Catherine Ferrier, says the only difference between some bottled water and tap water is that it is distributed in bottles rather than pipes.

Stephen Kay, spokesman for the International Bottled Water Association, says the fund's criticism was misguided. "The difference between bottled water and tap water is that bottled water's quality is consistent," he maintains.

However, according to the fund, regulatory standards for European and U.S. tap water are tougher than those applied to the bottled water industry. But Kay states that this was not the case. "Bottled water standards in the United States are at least as protective as those for tap water, and the industry is making a concerted effort to develop international standards," he says. While agreeing bottled water may be safer in areas where tap water may be contaminated, the fund said boiled or filtered tap water is still a better option for people with lower incomes.

The CODEX Alimentarius Commission is expected to approve a Code of Hygienic Practice for Bottled/Packaged Water and a General Standard for Bottled/Packaged Water. The commission is the worldwide food standards body under the World Health Organization.