Water is unlike any other commodity on Earth.

For a start, we can't live without it, for very obvious reasons. But it also underpins pretty much every activity we pursue in life - not just in our everyday lives, but in growing food, energy production and industry both large and small-scale.

Water is also unique in that it's pretty much indestructible - unlike most resources, it doesn't break down when heated up, but evaporates, constantly changing form to be transported to another place at another time. As Betsy Otto, global director at the World Resources Institute's (WRI) Water Programme, says, "the water we drink today dropped off the nose of Tyrannosaurus rex".