The global market for foodstuffs is depleting water sources in many parts of the world quicker than they can naturally be refilled.
The complex trade is increasing pressure on non-renewable groundwater, mainly used for irrigating crops such as rice, wheat and cotton.
Pakistan, the US and India are the countries exporting the most food grown with unsustainable water.
Researchers say that without action, food supplies will be threatened.
Around 43% of the water used to irrigate crops around the world comes from underground aquifers, as opposed to rivers and lakes. Many of these sources are being used up quicker than they can be refilled from rainfall.
Back in 2000, experts believed that non-renewable resources sustained 20% of global irrigation. In the 10 years to 2010, this increased by more than a fifth.
While scientists have long known about the depletion of groundwater, this new study sets out to understand how supplies are impacted by the booming international trade in food and crops.