By preserving local water resources and diverting water from other locations, Beijing has been able to keep tap water running for its 20 million residents, according to the municipal water authority.

Official figures suggest Beijing has only 100 cubic meters of water available per person locally, or one-tenth of the United Nations' "danger threshold."

To fight water scarcity, the city diverts water from nine water sources, including reservoirs in the nearby provinces of Hebei and Shanxi, as well as areas in the city's outskirts.

Although diverting water from elsewhere is considered a temporary measure, experts say it ensures Beijing's water security in times of urgent need.

About 6,900 hectares of rice fields in the upper reaches of the Miyun reservoir, the city's largest reservoir, have been used to grow corn and other water-efficient crops since 2007. This has allowed the reservoir to store an additional 50 million cubic meters of water each year, according to the municipal water authority.

Beijing has also been promoting the use of recycled water since 2003, fixing its price at 1 yuan (0.16 U.S. dollars) per cubic meter, 0.7 yuan lower than the standard domestic water price.

Households using recycled water have also been exempt from water resource fees and domestic wastewater treatment fees. A total of 680 million cubic meters of recycled water was consumed in 2010, accounting for 19 percent of the city's annual water supply.

The city has also taken advantage of the annual flood season to store water. Thanks to various rainwater collection measures, frequent downpours in Beijing this year filled 16 reservoirs with 35.6 million cubic meters of water, as well as adding 42 million cubic meters of water to the city's lakes and rivers.

Beijing uses water more efficiently than the rest of the country and just as efficiently as many developed countries, said Wang Hao, head of the water resources department of the China Insititute of Water Resources and Hydropower Research.