"A dozen years ago, desalination cost eight dollars per cubic meter," said Loic Chauvin, president of the France-based World Water Council.

"Now, we are at 80 cents, one tenth as much, and that is sure to fall," he said.

Gerard Payen, environment advisor to UN Secretary General Kofi Annan, agreed.

"Desalination is well along, works very well.

"However, it takes sea water and energy," he said. "Because the cost of desalination depends on the cost of energy," he said, "the technology is most highly developed in countries with sources of energy or which are on islands, where there is no other choice."

Desalination plants have adapted to the needs of dry and desert regions, to produce water for drinking, irrigation or industrial use.

Countries around the Gulf are the prime consumers. Two thirds of the world's desalination capacity is installed on the Arabian Peninsula.

Beyond the Gulf and the Caribbean, the United States, Spain and Israel use the technology.

Desalination is common at seaside luxury hotels, such as in Baja California or the Dead Sea, which have an additional source of clean water.

About 40 percent of household water in the twin-island Caribbean nation of Trinidad and Tobago is desalinated.

Reverse osmosis has slowly replaced instantaneous distillation technology.

US-based General Electric attended the World Water Forum in Mexico City, meant to shape global strategy toward improving distribution and eradicating water waste.

GE estimates that 2.6 billion dollars are spent on desalination. The company is building Africa's largest sea water desalination plant, in Algeria.

The Hamma plant outside Algiers will meet the water needs of 25 percent of the capital's population when it goes on line in 2007, and is cost-effective, according to GE head of marketing for the Americas, Gabriela Cabrera.

"It is not as expensive as many people think, the benefits are greater than the investment and it is a sustainable source of water," she said.

Environmental groups do not agree. They say the leftover salt jeopardizes marine flora and fauna and that desalination uses a lot of fossil fuel.

Wind-driven desalination plants in Cyprus and Malta, while attractive, are still small in scale.

Because transporting water is expensive, desalination is not well suited to serving inland needs, Gerard Payen said.

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