CONNIE HANSON / STOCK MARKET

Water terror was just as much a weapon in Somalia's civil war in the early 1990s. "People who were retreating [from the fighting] filled the wells with rocks," recalls Dr. Agostino Paganini, who works in Somalia for the United Nations Children's Fund. "Entire water systems in towns were looted. Generators were taken. Pipes were dug up and stolen." In the aftermath of the still-smoldering conflict, hundreds of thousands of displaced citizens in the arid East African nation were plagued by a lack of water. And what was left was dangerous. Since 1992, cholera and other waterborne illnesses have killed thousands of Somalians.

In future confrontations, attacks on water sources may be not just a tactic but the whole point of the battle. The Bosnian and Somali episodes could be previews of "water wars" that some environmentalists warn will eventually engulf the world. As the global population expands, putting pressure on the limited supply of clean freshwater, more armed conflict over who gets access to aqua pura seems inevitable. In one of the most volatile regions of the world, the Middle East, King Hussein of Jordan has said that only a dispute over water could break the peace his nation has established with Israel.

The stark truth is that in much of the world there isn't enough water, and where there is, it is being wasted, mismanaged and polluted on a grand scale. According to an April report from the United Nations and the Stockholm Environment Institute, by the year 2025, two-thirds of the world's population will be affected by water shortages. In 1995, 20% of the planet's people already had no access to clean drinking water and 50% lacked proper toilet facilities. "The world has got a very big water problem," says Sir Crispin Tickell, former British ambassador to the U.N. and one of the organizers of the 1992 Earth Summit in Rio de Janeiro. "It will be the progenitor of more wars than oil. World demand for water doubles every 21 years, but the volume available is the same as it was in Roman times. Something has got to give."

Global water use tripled just between 1950 and 1990. Increasing also is the disparity in water's availability to rich and poor. While a U.S. family may rinse and flush away as much as 2,000 liters of water a day, families in some parts of the developing world survive on as little as 150 liters, and they often have to travel several kilometers to obtain the precious fluid.

At least there are some hopeful signs. In Europe, the Middle East and Africa, nations that share access to rivers and lakes are meeting regularly to discuss how to divide up their water resources. Far from going to war over water, Jordan and Israel have set a good example of cooperation. Some nations are abandoning plans for environmentally destructive dams in favor of more modest water-development projects. Farmers and governments from Texas to Sri Lanka are adopting new conservation strategies and irrigation technologies designed to stop water waste. Sandra Postel, director of the Global Water Policy Project in Amherst, Massachusetts, contends that with existing technologies, farmers could cut their water consumption about 25%, while industry, by recycling cooling water, could save as much as 90%.

GOING DOWN THE DRAIN Symptoms of the water crisis are everywhere. Around the globe, water tables are falling, underground aquifers are being depleted, lakes are shrinking and wetlands crucial to the survival of plants and wildlife are drying up. More than 38,000 large dams (at least 15-m high), and innumerable smaller ones, block the world's rivers and streams. Some thundering waterways like the Colorado in the U.S. and the Yellow River in China are so dammed and diverted that they reach the oceans in a trickle, if that, for much of the year.

Although the surface of the "blue planet" is two-thirds water, 97% of it is undrinkable seawater, while an additional 2% is locked up in the polar icecaps. And the 12,600 cu km of water accessible for human use is distributed quite unevenly. Canada, for instance, is endowed with 26 times more per capita than Mexico.

Surprisingly, relatively little of the world's freshwater is needed for drinking and other personal use. About 25% of what we consume goes to industry, while 70% more supports farms and ranches. So agriculture is where future water shortages will be most acute. While irrigated land makes up only 17% of all farmland, it produces 40% of the world's crops. Since 1987, however, the amount of land under irrigation per capita has been in decline--in part because the world is running out of water to divert into irrigation ditches.

DANGER on TAP Even when water is available, a crucial question remains: is it safe to drink? Rivers and streams that run through human settlements are increasingly contaminated with pesticides from agriculture, industrial waste from manufacturing plants and, of course, untreated sewage. That makes water both the giver of life and the bearer of disease and death. The Stockholm report declared that, at any given time, half the people in the developing world are suffering from a water-related sickness. Another recent U.N. report noted that every day 25,000 of the afflicted die. An especially devastating outbreak was reported in July in southern Sudan, where thousands of people running way from a civil war were infected with sleeping sickness, a brutal illness carried by the water-bred tsetse fly that, if not treated effectively, drives its victims mad before killing them.

But poor countries are not the only ones concerned about the safety of drinking water. In the industrial world heightened attention is being paid to pollution of the water supplies with compounds containing chlorine, including polychlorinated biphenyls (pcbs), dioxins and other chemicals that are by-products of manufacturing processes and waste incineration. These substances, which pollute both the air and water and accumulate in the body fat of animals, fish and the humans who eat them, are suspected of causing cancer, birth defects and a variety of other ailments. The Women's Environmental Network in Britain claims that from 1% to 8% of the country's babies may have sustained at least slight nervous-system damage and memory loss as a result of exposure to dioxins and PCBs.

A newly discovered threat of these compounds is their ability to upset the endocrine system in humans and other animals. Inside the body, the chemicals mimic--and interfere with--the action of natural hormones, many of which are involved in reproduction. Some scientists fear that these hormone disrupters are having a negative impact on human fertility.

The following problem areas show how issues of water safety and supply are rising to the top of national agendas:

TAINTED STREAMS It's not surprising that the planet's most populous country would have some of the most pervasive water problems. A 1996 report by China's National Environmental Protection Agency concluded that 78% of the water in rivers flowing through Chinese cities was no longer drinkable. The Yangtze River, for example, is being polluted with 40 million tons of industrial and sewage waste a day. A report by the U.N. Development Program estimates that 79% of China's people are drinking contaminated water.

That is having a major impact on national health. Medical researchers say that the death rate among the people living along the Hei River in central Anhui province is 30% higher than the national average. No one from the area has been healthy enough in recent years to qualify for the People's Liberation Army. Two years ago, the government abruptly announced that the water from the 4,300-km Huaihe River, of which the Hei is a tributary, was unsafe to consume, which left 1 million people along the river's banks without drinking water. The military had to truck in water for a month while officials figured out what to do. The solution: 1,111 paper mills and 413 other industrial plants that dumped refuse into the river were shut, putting thousands of people out of work.

TROUBLE BEHIND THE CURTAIN An alarming number of rivers and lakes in eastern Europe are ecologically dead or dangerously polluted. Supply is sometimes an issue as well. Sofia, the capital of Bulgaria, ran critically low on water in 1995, and in the year it took to build a new pipeline, citizens sometimes could turn on their taps only every second or third day.

Eastern Europe has been the scene of a landmark legal dispute over the construction of a dam. In 1992, Slovakia, then a province of Czechoslovakia but now an independent nation, ignored objections from international conservationists and put into operation the Gabcikovo Dam on the Danube River along the border with Hungary. The Hungarians had been participants in the project, which provides electricity to the region, but pulled out in 1989 after opposition by environmentalists became a focal point of the country's democracy movement. In 1993 the two sides agreed to refer the case to the International Court of Justice in The Hague. During the years of legal deliberation, activist groups allege, Gabcikovo has caused a serious drop in the water table along the Danube, dried out thousands of hectares of forest and wetlands and reduced fish catches on some stretches of the lower Danube by 80%. Opponents of the dam hope for support from The Hague court, which heard final arguments in April, but fear an out-of-court settlement that would essentially leave Gabcikovo alone. Janos Vargha, who led anti-dam protests in Hungary, points out that both his nation and Slovakia are run by former communists most interested in economic growth. Says Vargha: "It's difficult to mobilize people on environmental issues now."