March 22 marks the annual observance of U.N. World Water Day and the beginning of a U.N.-mandated decade of action called "Water for Life." They are a call to U.N. agencies and other groups to focus their efforts on reversing the plight of the billions of people who lack access to safe water and sanitation to protect their heath. Organizers say the first water decade in the 1980s brought water to more than one billion people and sanitation to almost 770 million. But as VOA's David McAlary reports from Washington, the goal of sufficient safe water remains elusive as world population grows.

Earth may be unique in the universe for its abundance of water, amounting to 70 percent of its surface. But the image recalls the old sailor's lament, "Water, water everywhere, but not a drop to drink," for the vast majority of it is salty and unfit for consumption.

"It is really remarkable that on the blue planet, on a planet as abundant with water as the one on which we find ourselves, only three percent of the water resources on the planet are fresh water."

Erik Peterson

Erik Peterson of the Center for Strategic and International Studies in Washington points out that as small an amount as three percent is, only a tiny fraction of that percentage is available to us for daily use. Most of the world's fresh water is either frozen, locked underground or in swamps, leaving less than a drop in every liter for our needs. Half of that is already in use for agriculture, industry, and cities and towns.

But about one-sixth of humanity, one billion people, do not have safe water and 2.5 billion are without sanitation. U.N. statistics show that nearly half of all people in the developing world suffer diseases like cholera and diarrhea as a direct result. As population grows, Mr. Peterson says more will be exposed.

"We believe that these problems, as daunting as they are, are going to become all the more daunting in the future," he said. "By current estimates from the United Nations, we believe that by the year 2025, some three billion people across the world could face water shortages, in some cases life threatening water shortages."

Despite the minuscule amount of available fresh water, experts say there is enough to meet human needs. The real problem is that the infrastructure to deliver it, such as sewage treatment plants and pipes, is lacking in many countries.

At the World Bank in Washington, Claudia Sadoff makes the distinction between physical scarcity and economic scarcity.

"That is the issue, not so much of the resource not existing, but the resource being economically inaccessible," she said. "Forty-five percent of the world is essentially uncovered for water supply and sanitation."

The outcome is that much labor that could otherwise be economically productive in poor countries is spent toting water long distances on foot from rivers and lakes.

Development and stability are affected as nations and regions within nations compete for this scarce resource.

India and Pakistan, for example, are seeking World Bank mediation over India's desire to build a dam that Pakistan complains will reduce the water it gets from a river in Kashmir. Iran is building a huge dike that could divert some water it shares with Iraq.

Erik Peterson says water is a transboundary issue in many places.

"Two-hundred-sixty water basins across the planet are shared by two or more countries. Thirteen are shared by five or more countries," he said. "How successfully these countries deal with this critically short resource will, in effect, determine whether we have instability and conflict or whether we can define new pathways of cooperation going into the future."

In 2000, U.N. members set a goal of reducing the percentage of people lacking clean water and sanitation by half as one of several so-called Millennium Development Goals to be met by 2015.

But the Center for Strategic and International Studies says the effort is underfunded and will require an extra $15 to $30 billion in addition to the $30 billion already invested each year in development.

Experts say demand for water must be reduced as population increases.

Susan Murcott

For Massachusetts of Institute of Technology engineer Susan Murcott, part of the answer is new technologies to increase water efficiency. She favors simple, inexpensive ones for poor countries, such as portable solar evaporation stills to remove salt from water or drip lines connected to soil moisture sensors to release water sporadically onto farm fields as needed rather than flooding them.

Ms. Murcott has developed a filter of brick chips, rusty nails, sand, and gravel in a tub to eliminate arsenic and other contaminants from water.

"There may be a movement maybe not away from centralized drinking water and wastewater treatment plants," she noted, "but certainly an additional component of decentralized solutions that we are going to be seeing because water supply for so many people around the world is coming to people from decentralized sources."

To this end, the World Health Organization is collaborating with more than 200 governmental and non-governmental organizations, corporations, and universities in an international network to promote research into safe, affordable household water treatment, and ways to make it available to every person who needs it.