Beijing's tap water will not lead to the formation of stones in an organ or duct of the human body, known as lithiasis, an official said, in the latest effort to ease public doubts about water quality.

At the annual session of the city's political advisers on Monday, authorities denied rumors that the city's water might lead to lithiasis.

Beijing's water quality meets national standards and is safe to drink, Cheng Jing, director of the Beijing Water Authority, said on the sidelines of the ongoing annual meeting of the Beijing committee of the Chinese People's Political Consultative Conference.

Cheng is a member of the committee, which brings together political advisers.

"The hardness of the water is not caused by lithiasis, and any claim that the water can result in lithiasis is not scientific," he said.

"Residents in the city can feel safe drinking the water and there is no need for unnecessary anxiety," he said.

He made the comments in response to public concerns following water quality expert Zhao Feihong's claims that the capital's water has been worsening in recent years.

Zhao, a drinking water researcher at the Beijing Healthcare Association, said she has not drunk tap water for 20 years, as the capital's water has become increasingly polluted.

According to Cheng, the hardness of water in the city is 320 milligrams per liter, far below the national standard of 450 milligrams.

"The city's water quality standards are stricter than national ones," he said.

Beijing made water quality information public for the first time on Jan 15, saying that all 106 indicators of the city's water quality meet national standards.

Beijing Waterworks Group, the supplier of the city's tap water, said there are more than 300 monitoring stations in central urban areas.

Yuan Zhibin, an associate researcher at the Institute of Policy and Management of the Chinese Academy of Sciences, said all of the indicators are in accordance with international standards.

Cheng said the government will release more information about water to the public, including the hardness and saltiness of water so residents can truly understand the information.

He also said the agency that releases information about the city's tap water quality is an independent agency and the data provided is fair and impartial.

However, Cheng said the pipes in some older communities might pollute the water.

Yuan called for better maintenance of the water pipes.

"The water quality usually deteriorates after going through the water distribution system," he said. "Usually the intensity of microorganisms witnesses a slight increase during the transmission."

If sewage leaks occur, the water will be seriously polluted, he said.

"It is necessary for the government to check the pipes more often and come up with a set of emergency plans," Yuan said.

Cheng said the government will develop more measures to clean the pipes.

zhengxin@chinadaily.com.cn

(China Daily 01/23/2013 page4)