The Earth Policy Institute has echoed warnings from many sources that the world is using far too much water and could soon face a worldwide crisis.

The environmental think tank says that China, the US and India will face serious water shortages in coming years with significant consequences for global grain production. Lester Brown, President of the Washington DC-based Earth Policy Institute, says irrigation accounts for 80 per cent of global water use.

“The pumping from water underground has expanded to the point where it exceeds the rate of natural recharge from rainfall," Mr Brown said, “countries containing half the world's people are now experiencing extensive over-pumping and aquifer decline.”

The effects are most easily measured in the world’s driest areas; Saudi Arabia uses water ten times faster than its aquifers are refilling, while Kuwait has usage 25 times greater than the rate of replenishment. Reports say these countries are now facing serious declines in grain production, and the EPI says it is an indicator of what will befall the US, China and India.

"India is now one of the countries at greatest risk," Mr Brown says, "it depends heavily on irrigation for its grain production and that's why there are now an estimated 27 million irrigation pumps in India... the net effect of such a huge number of pumps is that the water table is dropping throughout most of the Indian subcontinent."