But water, like sunshine, has historically been free, and what is free is often not respected as it should be. Unsustainable and wasteful use of water has led to many ecological disasters, such as the drying up of the Aral Sea, seen as one of man's worst impacts on a previously flourishing environment.
World Water Day, sponsored by the United Nations, focuses attention on this precious and increasingly scarce commodity. The day also marks the beginning of the International Decade for Action on Water for Life, during which the world body is seeking to put the spotlight on the need to care for water resources and clean water.
The statistics show the urgent need. David Redhouse, a spokesman for the London-based charity Water Aid, says the impact on children is especially great.
"Every day there is a silent emergency in which a child is dying every 15 seconds; 6,000 children a day; 20 jumbo jets, in effect, crashing full of children," Redhouse said.
According to the World Health Organization (WHO), some 2.6 billion people lack even basic sanitation. Another 1.1 million must make do with unimproved and often unhealthy water sources.
Redhouse uses an individual example illustrating the difficulties people have in obtaining water:
"We know people like 12-year-old Erika Makalli in Tanzania, who has to get up at four o'clock in the morning to go and find water, and spends two hours walking to collect it, and even when she gets it it's bad water, so she's often sick and can't go to school," Redhouse said.
Among the regions with a looming clean water shortage is Central Asia, where the five republics share a network of nine big rivers. The irony of the situation is that rainwater in a normal year is not scarce. Stephanie Blencker is a spokeswoman for the Stockholm International Water Institute.
"Central Asia is quite challenging, because they do actually get a lot of rain. But the rain is coming [in a very short span of time]. So the challenge there is to improve the system to preserve that water, to improve the 'harvest' of the water," Blencker said.
The region is saddled with the remains of the inefficient, integrated water-use plan left over from Soviet days, as well as by the planting of high-water-use crops such as cotton. Since independence from the Soviet Union, the five republics have made some progress on rational water-sharing.
"I would especially like to mention the Aral Sea area, where the situation has been constantly improving -- at least in terms of awareness. The countries sharing the Aral Sea basin have started some cooperation, as there has been [excessive] water diverted from the two big rivers [flowing into the Aral Sea], the Syrdarya, and the Amudarya," Blencker said.
Sharing precious water supplies can be a difficult and even dangerous process. Take the Middle East, where Israel has only one main fresh water reservoir, the Sea of Galilee. Galilee's water comes from tributaries of the Jordan River -- the Hasbani, Dan, and Banias rivers, which rise in the mountains along the Syrian-Lebanese border.
Israel has been very touchy about any efforts to divert the waters reaching Galilee. It threatened military action in 2002 against Lebanon for planning to divert a tributary of the Hasbani. And in 1964, it actually did use punitive military action against Syria for trying to divert water from the Banias.
Today, as a more positive climate for peace re-emerges, Israel plans to sell water to the Palestinians in exchange for natural gas.
There is also persistent tension between Turkey, Syria and Iraq over the waters of the Euphrates and Tigris rivers, which rise in Turkey and wind their way through the cradle of civilization to the Persian Gulf.
Huge dam projects in Turkey are reducing the flow of the rivers. Both Iraq and Syria have maintained that, although they are downstream, they have acquired water rights that date back for centuries.
Syria has claimed that Turkey is trying to use water as a political lever to improve its political weight in the Mideast region. Ankara dismisses the charge.