BEIJING - A total of 812 million cubic meters of water from the south-to-north water diversion project have been delivered to Beijing as of Thursday, the municipal authorities announced on Friday.

The number is expected to reach 880 million cubic meters by the end of this year, said Sun Guosheng, director of the project's Beijing office.

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 water diversion project now provides 70 percent of Beijing's water supply. It reaches downtown areas and suburban districts including Daxing and Mentougou, benefiting more than 10 million residents, according to Guo.

Per capita water resources in the city has surged from 100 cubic meters to 150 cubic meters since the project went into operation last December, Guo said.

"The project has secured water resources for the capital while protecting underground water resources," Guo added.

The water diversion project is the world's largest at an estimated cost of 500 billion yuan (about $82 billion). It was officially approved by the State Council, China's Cabinet, in 2002, five decades after late Chairman Mao Zedong came up with the idea.

The middle route, which provides the primary flow to the 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 across Henan and Hebei provinces before reaching Beijing and Tianjin. It has benefited approximately 34 million residents along the route.