<p>A wealth of water—up to 1.6 million gallons a second—pours over Iguaçu Falls on the border of Brazil and Argentina.</p>

A wealth of water—up to 1.6 million gallons a second—pours over Iguaçu Falls on the border of Brazil and Argentina.

Photograph by Frans Lanting

Fresh Water

The amount of moisture on Earth has not changed. The water the dinosaurs drank millions of years ago is the same water that falls as rain today. But will there be enough for a more crowded world?

This article appears in the April 2010 issue of National Geographic magazine.
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