The U.N. food agency (FAO) marked World Water Day calling for greater efforts to combat water scarcity.  The agency's director general, Jacques Diouf, said this is the biggest challenge of the 21st century.  Sabina Castelfranco reports from Rome.

Mali villagers wait their turn at a water well

FAO Director General Jacques Diouf told a conference marking World Water Day that a global commitment is needed to deal with the worldwide problem of water scarcity.  He said countries must learn to share water fairly or conflicts over this vital resource can arise.

Diouf said global water use has been growing at more than twice the rate of population growth in the last century.  Water scarcity, he said, already affects every continent and more than 40 percent of the people on the planet.

The food agency projects by 2025, 2.8 billion people will be living in countries or regions with absolute water scarcity, and two-thirds of the world's population could be living under water stressed conditions.

"Water scarcity is first and foremost an issue linked to poverty," he said.  "Unclean water and lack of sanitation are the destiny of poor people across the world."

According to the FAO, 3,800 children die each day from diseases associated with a lack of safe drinking water and proper sanitation.  Diouf said the poor always pay more.

"People in the slums of developing countries typically pay for their water five to 10 times more than those who have access to piped water," he added.  "For poor people solving the water scarcity problem is about guaranteeing a fair and safe access to the water they need to sustain their lives."

Food security is also at stake.  Diouf said agriculture is the number-one user of water worldwide, accounting for about 70 percent of all freshwater withdrawn from lakes, rivers, and aquifers.  He added that demand from farms is set to increase by 14 percent in the next 30 years.

"It takes 1,000 liters to 2,000 liters of water to produce one kilo of wheat, and 13,000 to 15,000 liters to produce the same quantity of grain-fed beef," he explained.

Diouf said the water scarcity situation is being exacerbated by climate change, especially in the driest areas of the world.  He said access to water and food are rights that are universally recognized and that adequate institutional and legal instruments must be found for water sharing.