The middle route of the south-to-north water diversion project has transferred more than 10.8 billion cubic meters of water to north China as the project marked its third anniversary of operation.

Over the past three years, the water project has transferred 2.2 billion, 3.8 billion and 4.8 billion cubic meters of water, respectively,to north China, according to official data.

Designed to take water from China's longest river, the Yangtze, through eastern, middle and western routes to feed dry areas in the north, the diversion project provides 70 percent of Beijing's water supply.

It is the world's largest such project with an estimated cost of 500 billion yuan (77.4 billion U.S. dollars).

The middle route, the most prominent of the three due to its role in feeding water to the national capital, began supplying water on Dec. 12, 2014 as part of the project's first phase.

It begins at Danjiangkou Reservoir in central Hubei Province and runs through Henan and Hebei provinces before reaching Beijing and Tianjin.