Water is essential but growing populations are draining supplies

For life you need water but, millions of people on our little planet live in places with little or no water. The Horn of Africa is just one example.

The 16 most water stressed states are in the Middle East and North Africa. All are using more water than they receive - 700 times more in Libya's case. This area's population is increasing as grain production plummets.

The deep aquifers that enabled crops to green the deserts are almost exhausted. The oil that fires the desalination plants is dwindling. It's a 'perfect storm' of water, food and energy crises. Mexico City is sinking as its aquifers are sucked dry and freshwater tankers dock in Barcelona.

The planet's population tripled last century but the thirst for water grew six-fold, most of it sprinkled on fields. The UN predicts that by 2025, 2/3rds of us will experience water shortages.

China, struck by its own droughts, is importing water to produce its food and other goods. It is seeking to acquire land in wetter places to grow and send food home.

Global warming will evaporate more moisture but this may fall even harder in already wet areas rather than relieve arid areas. Desalination is very expensive, energy intensive and heavy on use of carbon.

Lack of clean water and sanitation in poor nations remains a problem especially as many donor countries have taken aid money away from water projects - it's not "sexy enough" - despite there being a Millennium Goal to half the number of people without basic sanitation by 2015.

Fresh water can be imported but at a price many can't afford. However, there may be a simple solution in some parts of the world: plug leaks, recycle waste and treasure each drop.