Despite meeting national standard, drinking water is somewhat unsafe, as experts say old pipes may taint Beijing water.
Despite claims that Beijing's water is safe to drink, experts said the quality of tap water is not completely guaranteed.
Beijing made water quality information public for the first time on Tuesday, saying that all 106 indicators of the city's water quality have reached the national standard. However, that does not mean tap water is safe to drink, experts said.
"Despite the 100 percent safety rate claimed by the authority, the water that comes out of the waterworks ... usually deteriorates after transiting through the water distribution system," said Yuan Zhibin, an associate researcher at the Institute of Policy and Management under the Chinese Academy of Sciences.
"The government's guarantee that the tap water is safe and meets the national water quality standard does not necessarily mean the tap water in all households also accords with national standards, as the water might get polluted in the pipes from the waterworks," he said.
"The concentration of microorganisms might witness an increase during the transmission," he said.
The 106 water quality indicators include the intensity of pesticide residue, the concentration of heavy metal and the content of total coliform group.
Zhao Feihong, a drinking water researcher at the Beijing Healthcare Association, said all of the indicators are in accordance with international standards.
Despite the government's claim, residents still need to be careful of the effect pipe pollution can have on tap water, she said.
Some water pipes in older residential communities lack anticorrosive coating, and the water can become polluted during transmission.
According to Zhao, the content of microorganisms might increase during transmission, especially when sewage leaks occur. Zhao said the pipes should be checked often.
According to the Beijing Waterworks Group, which is responsible for the water supply in the capital, the city has more than 300 water quality monitoring stations in central urban areas, including colleges, offices and residential areas.
"The samples are from all over the city and can provide an impartial summary of the city's water quality," said Hu Bo, director of the water supply department of the Beijing Water Authority.
To further ensure the quality of drinking water, many residents drink bottled water or use water purifiers.
Hu Yali, a 46-year-old Beijing resident, bought a water purifier a few months ago for her apartment to ensure the water her family drinks is safe.
"I can't detect an obvious difference between water from the tap and the purifiers, but the tester does show a decrease in the content of microorganisms," she said. "As my daughter-in-law is expecting a baby, the purifier at least makes me feel safe."
Wang Yu, who sells water purifier systems, said the market for purifying systems has been very popular since the second half of last year.
"More and more residents are attaching importance to the quality of water as well as their health and well-being," he said. "They have started to realize the quality of water is as important as the quality of food."
Zhao warned that the misuse of water purifiers could also lead to more pollution.
"Residents need to frequently clean and replace the filter, or the water will be more polluted," she said.
She also stressed the importance of an emergency mechanism in case of water pollution.
"It's a giant step forward that the government has started making the test results available to the public. However, what measures to take when water pollution occurs or the index fails to meet the standard is more important," she said.