Major economies are pushing for substantial increases in the price of water around the world as concern mounts about dwindling supplies and rising population.

With official UN figures showing that 1 billion people lack access to clean drinking water and more than double that number do not have proper sanitation, increases in prices will be – and in some countries are already proving to be – hugely controversial.

However experts argue that as long as most countries provide huge subsidies for water it will not be possible to change the wasteful habits of consumers, farmers and industry, nor to raise the investment needed to repair old supply systems and build new ones. And price rises can be managed so that they do not penalise the poorest.