By Lisa Simeone

The most precious and dangerously threatened substance in a troubled world is not oil.

Ask someone what causes wars in different parts of the world, and you're likely to get a few all-purpose answers. You have the standard human vexations: greed, fear, intolerance, general tendency toward violence. And then you have the more practical reasons, such as natural resources - especially, people will say, oil. After all, modern societies depend on oil, and we all know the Middle East is rich in it. "No war for oil" became a rallying cry in protests against the recent war in Iraq. But for a lot of the world's population, oil is the least of it. Water is the thing.

The scenes of Iraqis scrambling for water in the wake of war might lead one to believe that it takes a cataclysmic event to disrupt the flow of this seemingly endless resource. Not so. All over the world, including in this country, water is running out.

Newspaper and magazine articles have started to catch up, with a spate of books published recently about the worldwide water shortage. Now, even non-water-wonks are beginning to hear terms such as "aquifer depletion," "equitable use" and the seemingly simple "water management." These are technical terms, not exactly designed to induce passion. Yet passion there is aplenty in the story of water, as several of these books make clear. Water Wars by Diane Raines Ward (Riverhead Books, 280 pages, $24.95) is the newest of the bunch, and aptly titled. But as all the books reveal, wars are already being fought over water, with more to come.

It's easy to believe, for instance, that the tension in the Middle East is all about religion and nationalism. Take the Six-Day War of 1967. According to Israeli Prime Minister Ariel Sharon, "In reality, it started two-and-a-half years earlier, on the day Israel decided to act against the diversion of the Jordan [River]."

Israel, through the canals and pipes of its National Water Carrier, had been diverting water from the Jordan River to deliver water to its people. The Jordan has its source in several streams that originate in Syria, Jordan and Lebanon. Arab League leaders, angered by the water diversion downstream, decided to do their own diversion upstream.

Israel warned its neighbors that if they tried to cut off any of the water supply there would be hell to pay. They did, and there was. Israel bombed water projects on the Hasbani and Wazzani rivers in Lebanon and the Yarmouk River dam in Syria, then annexed the Golan Heights, thus ensuring control of the Jordan River's headwaters.

As late as last September, U.S. diplomats were called in to mediate when Israel and Lebanon exchanged angry words over construction of a Lebanese water project to pump water from the Wazzani to the dry towns of southern Lebanon. (Is your head spinning yet? Among its many virtues, Marq de Villiers' book, Water [Houghton Mifflin, 368 pages, $15], provides maps, a feature the other two books lack.)

Today, Israel controls most of the aquifers in the West Bank and Gaza Strip. Water is considered a security issue; you cannot tour the network of valves and canals of the National Water Carrier, and officials will not say how much water is actually transported from the Jordan River. Israel issues licenses to all residents who want to dig wells. The authorities issue more licenses to Jewish settlers than to Palestinians, and settlers' wells can run as deep as 750 meters, Palestinian wells 140. Here, in desert land, water is political.

And so it is all over the world. Turkey holds the upper hand, or more accurately, the upper waters, in a dispute over the Tigris and Euphrates. Turkey is building dams to control the two powerful rivers, for irrigation, consumption and hydroelectric power. Downstream, Syria and Iraq stand to lose water. The attitude of the Turkish government is, "You have oil, we have water."

In 1990, when three dams were being proposed on the so-called Blue Nile in Ethiopia, where the river originates, Egypt's then-Deputy Minister of Foreign Affairs Boutros Boutros-Ghali stated that the construction of any dam on the upper reaches of the Nile would be considered an act of war.

The Jordan, the Tigris, the Euphrates, the Nile, the Indus, the Rio Grande - all are examples of international river basins. Many countries share them, and all believe they have a right to use the water in them.

The question of right vs. need is a prime focus of Jeffrey Rothfeder's Every Drop for Sale (Tarcher/Putnam, 205 pages, $24.95). Is water a right, like the air we breathe, or a need, like oil, on which we've come to depend? Rothfeder is a passionate proponent of the former definition, and his book is the most accessible of the three to a general audience.

Though all cover many of the same subjects - consequences of dam-building, over-draining of aquifers, water-transportation techniques (wait till you read about Medusa bags!), the world's hot spots - Rothfeder spends less time on the minutiae of cubic feet, rates of evaporation, levels of salinity and other highly technical information.

His book reads more like an essay and should be eye-opening to a variety of readers. It does lack footnotes, however, a hindrance if you're interested in studying the subject more deeply. And its index is sparse, missing some critical entries. But his stories of the privatization of water, and the people affected by it, are riveting - especially the drama of the residents of Cochabamba, Bolivia.

In the spring of 2000 the Cochabambans fought a water war against their own government, which had cut a deal with the U.S.-based Bechtel Corp. to retool the city's failing water system and deliver clean, potable water. Price-gouging followed, talks broke down and the citizens eventually rioted. People were killed, injured and taken away to prisons and never seen again.

By the time it was all over, the citizens had won. They forced the Bolivian government to break its contract with Bechtel, and to pass a law returning all future water decisions to local communities. (Bechtel is, of course, the lead contractor for U.S.-financed reconstruction in Iraq.)

All three books are also personal odysseys, as the authors talk about traveling the globe and seeing firsthand the effects of man's attempts to manage water. Ward fleshes out historic characters such as the great 19th-century water engineer William Willcocks, who built the first dam across the Nile, and Sir William Hudson, who built the Snowy Mountains Hydro-electric Scheme in Australia.

These men were explorers of the old school, who believed in harnessing nature to help people. The fact that their projects had unintended consequences - malaria brought on by an increase in mosquitoes, more ferocious floods when rivers do breach dams, flooding of wetlands crucial to filtering waste, build-up of silt - does not diminish their accomplishments. As de Villiers writes, "Thus are ecosystems ever changed, more by the cumulative deeds of good men doing what they believe in than by the rapacious actions of green demonology."

There are plenty of stories of the United States, as well, with coverage of the Hoover Dam, the Tennessee Valley Authority (a model for the world), the Mississippi River, the Florida Everglades and, most vividly, the tale of a desert town called Los Angeles and how it got - rather, stole - its water.

The fictionalized version in the movie Chinatown is not far off the mark. All the authors see the entire Southwest, which is rapidly depleting its water supply, as a cautionary tale. But de Villiers reserves particular scorn for California, calling its method of water management "the planet's most expensive welfare system."

UNESCO has calculated the absolute bare-bones minimum of clean water required as 50 liters per person per day - that's for drinking, cooking, bathing and sanitation. The average American flushes half that down the toilet with every use. My household uses a hundred times that. Yet I pay only about 18 bucks a month for it. Water in this country is plentiful and heavily subsidized. ("Get the government out of my life" doesn't seem to extend to faucets, toilets and garden hoses.)

We may have the luxury of such profligacy today, the authors say, but we won't forever. And rather than wait for a crisis such as the one in Cochabamba, or similar ones now heating up in Arizona, California, Florida and here in Maryland, we'd better take a look at our water bills, and the management behind them, a lot more closely.