Within a few days, water that has traveled more than 800 miles for two weeks in one of the world’s most ambitious, and controversial, engineering projects is expected to begin flowing through Beijing faucets.

The water began its journey from upper reaches of the Han River, the biggest tributary of the Yangtze, on Dec. 12 through the central route of the South-to-North Water Diversion project, the second of three routes in a major effort to transfer water from China’s south to its arid north. It was collected in the Danjiangkou Reservoir in Hubei Province before being moved to the capital, where it is expected to provide nearly a third of the city’s annual water needs.

Still, some experts say that the costly endeavor — Chinese newspapers put the price of the central section at more than 200 billion renminbi, or $32 billion — is no long-term solution. They say that Beijing will continue to face severe water shortages, as the region’s surging population and economy continue to feed demand and pollution degrades available supplies.

One scientist with the Department of Water Resources in China said that the new inflow of water would provide some relief to the capital but would hardly compensate for the overexploitation of aquifers. Each year, Beijing consumes about 3.6 billion cubic meters of water — 127 billion cubic feet or 950 billion gallons — about half of which came from underground sources before the central route was completed. Water tables have dropped by about 42 feet since 1998.

“Beijing has around six billion cubic meters of overpumped aquifers that need to be replenished,” said the scientist, who spoke on the condition of anonymity because he was not authorized to talk to foreign journalists. “Merely relying on the central route won’t solve the shortages. The fundamental solution should be to conserve water and control the size of Beijing’s population.”

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Last year, in an interview with the magazine Oriental Outlook, Wang Hao, who leads the Department of Water Resources, warned that Beijing’s underground water was being depleted. “The underground water level drops 90 centimeters” — more than 35 inches — “each year,” Mr. Wang said.

In July, the director of the Beijing office of the South-to-North Water Diversion project, Sun Guosheng, told the state-run news agency Xinhua that though the water from the Danjiangkou Reservoir would improve Beijing’s supply, it would not be a complete solution. More emphasis must be placed on conservation, Mr. Sun said. “The entire society needs to tighten water faucets,” he said.

But that could prove difficult. One reason is aging water pipelines.

“The pipeline networks in big cities, including Beijing, are old and water has been leaking,” said Wang Shichang, a specialist in water resources and a former professor at Tianjin University. Mr. Wang said in an interview that a major overhaul of the system was necessary but that little had been done. “People are very aware of the concept of saving water,” he said, but “there has not been much progress in recent years.”

Another reason is the cheap price of water. In May, for 90 percent of Beijing residents, the cost of a cubic meter of water rose 25 percent to 5 renminbi, or 80 cents. To encourage conservation, the price should be at least twice that, but there are no such plans under discussion, said the scientist with the Department of Water Resources.

In 2008, to help overcome Beijing’s water shortages, an emergency supplement from reservoirs in Hebei, the province that encircles Beijing, was set up. This had delivered 1.6 billion cubic meters of water to the capital by last April, when the supply was halted.

Construction of the South-to-North Water Diversion project, inspired by Mao Zedong’s remark in 1952 that the north could borrow some water from the south, got underway in 2002. Despite much criticism of its cost and possible ecological damage, the first of its three projected sections, an eastern route running from the Yangtze to Shandong Province, began operations in December 2013. A third, western section remains in the planning stage.