The quality of water delivered to Beijing through the first phase of the South-to-North Water Diversion Project's central route will be guaranteed, environmental officials have said, as a two-month water delivery test on the section in Henan province started early this month.

The main canal of the project's central route south of the Yellow River began a water flow test on Thursday to check the construction, equipment and water quality of the project. The project has entered a final preparation phase three months before the deadline of delivering water to China's northern cities, including Beijing and Tianjin.

Tang Jianli, deputy inspector with the environmental protection bureau of Nanyang, one of the major water source areas, said monitoring has shown that the water in the Danjiangkou Reservoir meets the standards for water that will be delivered to northern China.

"We have also built a number of urban sewage treatment plants in the neighboring counties and districts near the reservoir to ensure the water quality," he said.

The reservoir, located in Henan and Hubei provinces, will be a major source of water for the central route and will deliver an average 9.5 million cubic meters of water to northern China each year.

In response to media reports that the Danjiangkou Reservoir is facing pollution problems, including high levels of nitrogen and phosphorus in the water, He Fengci, deputy director of the Jiangsu South-to-North Water Diversion Project office, said authorities adequate measures to ensure that the water that is delivered will be safe.

"Even if the problem does exist, the nitrogen and phosphorus would be degraded in the delivery process," he told People's Daily on Thursday.

The water diversion project, which was started in 2002, will take water from the Yangtze River and its tributaries in the country's south.

Qi Shengbo, deputy director of the Nanyang South-to-North Water Diversion Project office, said that if necessary, the authority will reduce the amount of water used to produce electricity in the reservoir to ensure the water supply.

Contact the writers at xuwei@chinadaily.com.cn and qixin@chinadaily.com.cn