A crude oil leak from a pipeline owned by a unit of China National Petroleum Corp. (CNPC) is to blame for water contamination that has affected more than 2.4 million people in the Chinese city of Lanzhou, in the the landlocked northwest part of the country, according to Chinese media reports Saturday.
The leak poisoned the water source for a water plant, introducing hazardous levels of benzene into the city's water, according to China's official news agency Xinhua.
Residents scrambled to buy bottled water after authorities warned against using taps, in scenes reminiscent of a municipal water ban in the United States, following a coal-processing chemical spill that affected 300,000 West Virginians in January.
Xinhau cited Yan Zijiang, Lanzhou's environmental protection chief, as saying that a leak in a pipeline owned by Lanzhou Petrochemical Co., a unit of CNPC, was to blame for the water contamination.
The spill comes amid a push by Beijing to reign in pollution in China, which has seen environmental degradation come along with fast economic growth. Last week, a government review of 25,000 companies found 2,000 failed to meet pollution standards.
Lanzhou, a heavily industrialized city of 3.6 million people in the northwestern province of Gansu, ranks among China's most polluted centers.
Lanzhou Petrochemical is a major refinery with a total refining capacity of 280,000 barrels per day (bpd). The company plans to process 195,000 bpd of crude this year, industry sources have said.
Levels of benzene, a cancer-inducing chemical, in Lanzhou's tapwater on Friday rose 20 times above national safety levels, Lanzhou authorities said in a press release.
Lanzhou city authorities said Friday that they found 200 micrograms of benzene per liter of water. The national safety standard is 10 micrograms.
The United States Environmental Protection Agency sets its maximum limit for benzene at 5 micrograms per liter of water, but says zero is the ideal amount.
The high benzene levels forced the city to turn off the water supply in one district and city officials warned citizens not to drink tap water for the next 24 hours.
The city official Yan told Xinhua on Saturday that the leak had been located and repairs were underway.
By late Saturday morning, Xinhua said benzene levels were confirmed safe at five out of the six water monitoring sites.
The water supply company, Lanzhou Veolia Water Co, is majority-owned by the city government, with Veolia China, a unit of French firm Veolia Environment, holding a 45-percent stake.
On Friday, Veolia said in a release that an initial investigation found the high levels of benzene were caused by contamination at one of the two culverts that transfer raw water from a sedimentation plant to the water treatment plant.
According to Xinhua, investigators found crude oil in soil along a duct between two water works owned by Veolia Water.
"The channel has been carrying water to Veolia Water's No.1 and No.2 plants for decades. Under this ditch lies Lanzhou Petrochemical's oil pipeline," the city's environmental protection chief Yan told Xinhua.
A Veolia spokeswoman in Hong Kong declined to comment on Saturday and referred all questions to city authorities.
CNPC is parent company of PetroChina Co. A PetroChina spokesman could not immediately be reached for comment.
Meanwhile, according to a report Saturday in The New York Times, Sinopec, another Chinese petrochemical firm, has started aggressive exploration of natural gas by hydraulic fracturing, prompting concerns for water quality and worker safety.
Al Jazeera and Reuters