Updated at 1:30 p.m. ET on 2014-4-25
Authorities in the central Chinese city of Wuhan have launched a probe into the contamination of a major river supplying drinking water to 300,000 people, official media said on Thursday.
The incident, the latest in a string of water pollution scares across China, has sent thousands of the Hubei provincial capital's 10.22 million residents rushing to supermarkets to stock up on bottled water, media reports and residents said.
"I heard that the water supply is polluted," an Wuhan resident surnamed Huang told RFA's Mandarin Service on Thursday. "I heard the water supply would be shut off for five days."
"[Everyone's] buying up that bottled distilled water in large quantities," Huang said.
Two water supply companies had suspended production on Wednesday after tests showed that the Hanjiang river near Wuhan—a conurbation of three major river ports—contained "excessive amounts" of the pollutant, ammonia nitrogen, Xinhua news agency reported.
The two companies, Baihezui and Yushidun, supply tap water to more than 300,000 local residents.
"Disqualified water" from the two waterworks has now been prevented from entering the city's central water supply network, the municipal government said in a statement.
It said current drinking water supply is being tested every hour, and is currently "up to standard," Xinhua said.
It said local environmental officials are investigating the source of the pollution.
An official who answered the phone at local government offices declined to comment, saying journalists should call the propaganda department.
Repeated calls to the Dongxihu district government propaganda department were picked up and immediately cut off during office hours on Thursday, however.
An official who answered the phone at the Wuhan municipal environmental protection bureau referred calls to its crisis center, but declined to provide the number, which was unlisted in local directories.
An employee who answered the phone at the Wuhan mayor's hotline said they had no information about the cause of the pollution.
"As far as the actual cause is concerned, the relevant departments have not given us any information," the official said.
A resident of Wuhan's Hanjiang district surnamed Zhang said he had been unaffected, but local people were anxious to know more.
"A few hundred thousand people [were affected], but this is a city of a few million, so the impact isn't so great," Zhang said.
"People are very concerned about these issues, and we are stepping up efforts to get the government to make this information public," he said.
"This has alarmed everyone in Wuhan."
A volunteer with the non-government environmental group Friends of Nature told RFA that ammonia-nitrogen is a waste product formed from the breakdown of organic matter.
"According to my understanding, ammonia-nitrogen is pollution caused by the breakdown of organic matter like manure," the volunteer, Liu Jun, said. "It has to do with human or animal waste."
He said the authorities had given little information to the general public, however.
"I haven't received any form of mass communication," Liu said. "I found the information by myself online."
"I don't think they've done enough from a transparency point of view; this sort of information should be put out promptly, with at least a broadcast text message," he said.
"They didn't do that, and it's not good enough."
Lanzhou water crisis
Residents of the northwestern Chinese city of Lanzhou last week also hit out at local authorities for a lack of transparency after a drinking water crisis sent thousands of people to supermarkets in a panic-stricken bid to buy bottled mineral water.
Stores in Lanzhou were packed with jostling shoppers desperate to buy the last cases of bottled mineral and distilled water after the authorities announced that levels of the carcinogen benzene, a cancer causing substance, had been detected in the city's tap water at 20 times the legal limit on April 14.
Chinese consumers are reeling in the wake of a string of public health scandals affecting foodstuffs and medicines in recent years, including melamine-tainted infant formula milk, used "gutter" cooking oil, and tainted vaccines.
Officials have admitted that China is facing a "grave" environmental crisis, with more than half its cities affected by acid rain and one-sixth of its major rivers too polluted to use for watering crops.
In March 2013, Shanghai's water quality made world headlines after thousands of swollen and rotting dead pigs were found dumped in the city's Huangpu River, prompting many residents to turn to bottled water in spite of assurances by local officials that supplies were up to standard.
More than three decades of breakneck economic growth have left China with a slew of environmental problems, causing a fast-maturing environmental movement to emerge among the region's middle classes and farming communities alike.
But activists say cleaning up China's highly polluted waterways could take far longer than the three decades it took to foul them up in the first place.
Reported by Yang Fan for RFA's Mandarin Service. Translated and written in English by Luisetta Mudie.