Panicking residents in the northwestern city of Lanzhou, Gansu, swarmed supermarkets to clear bottled water off the shelves yesterday after authorities warned the city's drinking water contained excessive levels of a carcinogenic chemical.
The Lanzhou government yesterday afternoon asked residents not to drink tap water for 24 hours, Xinhua reported. The water supply was cut off in one industrial district, after tests taken in the morning showed benzene levels had reached 200 micrograms per litre - 20 times the national safety limit.
The widely used industrial chemical, when ingested through food or drinks, can cause vomiting, dizziness, convulsions and even death in large enough doses.
Photos posted online showed residents waiting in long queues to buy bottled water. A shop assistant in the city said: "I was delivering cartons of bottled water to a nearby store, but the van was stopped on the way by shoppers who snapped up all the water in minutes."
To help allay public fears, the government said carbon filtering was being used to absorb the chemical, and insisted the tap water was safe for "household uses other than drinking" - a claim that raised concerns with some environmental experts.
Du Sha, a Greenpeace toxins specialist, said benzene was harmful even by indirect contact.
"The level of the benzene was already 20 times the national safety limit … tap water is not only unsafe for drinking, it will also irritate eyes and skin when used for washing," Du said.
Authorities were still struggling to pinpoint the source of the contamination.
The water supply company is majority owned by the city government, but the daily operations are carried out by British firm Veolia Water, which holds a 45 per cent stake.
Veolia said chemical plants might have spilled sewage into a channel near a water plant, Xinhua reported. Tian Hong, head of Lanzhou's water quality monitoring station, said "problems were found in a three-kilometre channel" that connected parts of the water plant, and that the channel had been closed.
The Gansu publicity department said the Yellow River, which runs through Lanzhou and supplies 90 per cent of the city's tap water, was not contaminated, although tests were continuing.
Du said many petrochemical plants in Lanzhou were built along the Yellow River.
"If the Yellow River is polluted, that would be a really serious problem as downstream cities will also be affected," Du said.
Lanzhou residents complained last month of a foul smell in tap water.More on this: