The world contains an estimated 1 400 million cubic km of water. Only 0.003% of this vast amount, about 45 000 cubic km, are what is called "fresh water resources" - water that theoretically can be used for drinking, hygiene, agriculture and industry. But not all of this water is accessible. For example, seasonal flooding makes water extremely difficult to capture before it flows into remote rivers.

In fact, only about 9 000-14 000 cubic km are economically available for human use - a mere teaspoon in a full bathtub when compared to the total amount of water on earth. With the population increasing by two billion by 2030, will this be enough water to sustain human life? Of course, quantity isn't the only issue. The quality of the water supply is also important.