What's causing water shortages?

The shortage of water in some parts of the world is one of the greatest risks of our time.

And the battle to secure supplies of the most vital life-giving commodoties is political, environmental and economic.

The UN says there's an abundance of fresh water but that it's unevenly distributed around the world - and supplies are under increasing pressure.

Such as in Cape Town, where around four million South Africans are running dry.

But what's being done to confront the crisis which affects at least one billion people around the globe?

And what's caused the crisis in the first place?