Many people believe that the 3th World War will be fought over water. But not only is its scarcity a cause of concern, but also its distribution. In this video you can discover how water is distributed around the world, and also get to know another important issue: the residence time of water, which depends on where a water drop lives. Whereas a drop of water can live up to 10,000 years in deep groundwater storage, the residence time of water in rivers and lakes varies from 2 months to 100 years. Therefore, if we waste water, we will end up with the fresh water available and nature won’t have enough time to restore it and make it available again. By Gal·la Argelada.