"There really is no water," Uri Saguey, the chairman of Mekorot, Israel's state water company, said Thursday in a public plea for desalination investment. "Any entrepreneur who gets government approval for desalinating water should be blessed."

Desalination projects can be completed quickly, says IDE, which has been building them elsewhere in the world for 30 years. This April, IDE began operating its latest plant, in Larnaca, Cyprus, just 14 months after breaking ground. "Israel could use 10 of them," Mr. Waxman said.

The Israeli contracts, expected together to be worth perhaps $250 million, will be among the most hotly contested anywhere in the increasingly competitive desalination industry, experts say. Annual revenue from the water projects is expected to triple, to $100 billion, over the next two decades, with most of the growth coming from the new filtration systems that will be showcased in the Israeli plants.
Instead of heating and distilling the brine, which requires abundant surplus energy, these plants strain salt out of seawater with synthetic membranes in a process consuming half as much power.

World demand for these improved reverse-osmosis systems - also used for purifying brackish and polluted water-is now growing at 10 times the pace of thermal desalination, estimates Eric Jankel of Aqua Resources International, a consulting company in Evergreen, Colo. Israel, where universities have long been world leaders in desalination research, is expected to be a proving ground for further technological advances in the field, he said.

"The Ashkelon plant will be the largest pure seawater reverse osmosis plant in the world, " Mr. Jankel said. "That gives it a significance beyond the Middle East."
Also competing for the Ashkelon contract is Ionics Inc. of Watertown, Mass., which says it has the most membrane-based desalination plants-about 3,000 but many of them relatively small-in operation worldwide. The third approved bidder is a consortium led by Cadagua, part of the Ferrovial Group of Spain, which has built desalination plants in Tunisia, Cyprus and Spain.

Elsewhere in the world, more than 30 large seawater desalination plants are now in the construction or planning stage. With desalination becoming increasingly efficient and affordable, it is beginning to look like an ideal growth industry: the raw material is abundant, and demand for the finished product is almost unquenchable.

The World Meteorological Organization says that by 2025 almost a billion people will face serious water shortages. And much of this population will be living on or near a coast, from the South China Sea to Southern California to here in the southern Mediterranean.

"There is huge competition now in the business, so prices are decreasing," said Jean-Marie Brun, a water systems engineer for Vivendi Environnement of France, the single biggest company in the field. "And the technology, which is very good now, is getting better all the time."

The largest membrane-based desalination plant now under construction is in Tampa, Fla., where the Poseidon Resources Corporation and the Covanta Energy Corporation will be producing 25 million gallons of water a day for about $1.75 per thousand gallons, the lowest rate in the world. But the estuarine waters of Tampa Bay are far less salty than the ocean, cutting filtration costs.

In Trinidad, Ionics is building what will be the biggest ocean-desalination plant in the Western Hemisphere, with an output of 29 million gallons a day at about $2.50 per thousand gallons. IDE's plant in Cyprus provides 16 million gallons of drinkable water a day for a similar price. But with improving technology and economies of scale, contractors for the Israeli projects are expected to keep the cost close to $2 per thousand gallons.

Cadagua and Ionics both have local Israeli partners. But IDE, with more than 300 plants operating on five continents, is the only Israeli company with a proven record abroad. Owned by two private Israeli industrial conglomerates, Israel Chemicals Ltd. and the Delek Group Ltd., IDE builds desalination devices for export in Ra'anana, north of Tel Aviv, and argues that it should be the beneficiary of a little home-team favoritism in the tender.