China's south-to-north water diversion project has supplied about 34 million people since it went into partial operation in December, new official data showed.

More than 1.7 billion cubic meters of water has been delivered through the 1,432-km middle route of the project to Beijing, Tianjin and the provinces of Hebei and Henan, the route's management bureau said on Wednesday.

The project now supplies 70 and 80 percent of the water consumed in Beijing and its neighboring Tianjin, respectively, the bureau said.

The water diversion project, the world's largest at an estimated cost of 500 billion yuan (about 82 billion U.S. dollars), was designed to take water from China's longest river, the Yangtze, through eastern, middle and western routes to feed dry areas in the north.

It was officially approved by the State Council, China's cabinet, in 2002, five decades after Mao Zedong came up with the idea.

The middle route, the most attention-grabbing of the three due to its role in feeding water to the Chinese capital, started 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 across Henan and Hebei before reaching Beijing and Tianjin.

The other two routes are not yet operational.