The middle route of the south-to-north water diversion project has transferred a total of 5 billion cubic meters of water to Beijing since it began.
Between 2008 and 2014, a section of the middle route sent about 1.6 billion cubic meters of water from neighboring Hebei Province to Beijing in an emergency water supply program.
Since December 2014 when the middle route started transferring water from the Danjiangkou Reservoir in the middle reaches of the Yangtze River, about 3.4 billion cubic meters has been transferred to Beijing.
Of the total, 3.5 billion cubic meters has been supplied to tap water plants and the rest flowed to reservoirs, emergency water sources, rivers and lakes.
The project has eased the pressure on water supply and improved the environment in Beijing, according to the project's Beijing office.
The project is scheduled to increase water supply by bringing 1.5 billion cubic meters of water annually to Beijing by 2020, the office said.
The water diversion project, the world's largest, was designed to take water from the Yangtze to feed dry areas in the north through eastern, middle, and western routes.
The middle route begins at the Danjiangkou Reservoir in central China's Hubei Province and runs across Henan and Hebei provinces before reaching Tianjin and Beijing.