China's richest provinces are having a huge environmental impact on the country's water-scarce regions, according to a new estimate by the International Institute for Applied Systems Analysis (IIASA) and the University of Maryland.

The new paper used the controversial concept of "virtual water," an economic idea used to estimate water flows through trade and track how water is traded through agricultural products and other goods that require water to produce. But while previous claims of water flows had treated all water equally, the new study factors in water scarcity for regions. 

Virtual water was invented by professor John Anthony Allan of King’s College London. It has also been used to claim that it takes 140 liters of water to make a cup of coffee. The 'virtual water' contained in grain imported into just one region of the mid-east is equal to all the water in the Nile, so critics immediately see the problem with it. People use real water - in a simulated world, there would have been wars over water in the mid-East 50 years ago.

But it persists in water management and environmental activism circles and the new paper says that developed regions in China are not only drawing from their own water resources but also contributing to water depletion in other water-scarce regions of the country through imports of food and other water-intensive goods. China is not running out of water, but they are running out of virtual water.    

"When goods and services are exchanged, so is virtual water," says IIASA and University of Maryland researcher Laixiang Sun. "For example, it takes about 1,600 cubic meters of actual water to produce one metric ton of wheat. When a country or region imports a ton of wheat instead of producing it domestically, it saves most of that."

In China, like in most countries, water resources are distributed unevenly. Virtual water claims that trade between these water-scarce regions tends to draw more sharply on water resources in the less developed, poorer regions - the provinces of Shanghai, Shandong, Beijing, and Tianjin use a lot of virtual water at the expense of less-developed provinces such as Xinjiang, Inner Mongolia, and Hebei. Not actual water, virtual water embedded in food.

"Importing water-intensive goods from one water-scarce region to another doesn't solve the problem of water scarcity—it just shifts the pressure to other regions," says co-author Klaus Hubacek, a researcher at the University of Maryland. 

As is done in every country, China has water transfer projects to divert water from water rich areas to water poor ones the authors suggest that replacing imports from the North with goods produced in the South could be a more efficient solution to the problem.

Let the people drink virtually!