The city of Lanzhou, situated in the north of China, is in the midst of a serious drinking water crisis as a crude oil pipe leak has contaminated water supplies to the city with benzene, Reuters reported.

A crude oil pipeline operated by a subsidiary of state-owned China National Petroleum Corp. leaked and contaminated the source water feeding a local water plant with benzene to levels 20 times higher than national safety levels. The water supply to approximately 2.4 million people, out of the area's 3.6 million residents, was cut off and citizens were warned not to drink any tap water for a period of at least 24 hours.

Lanzhou city officials and representatives of the water company have been monitoring levels of benzene across water pipes to make sure there is no risk to public safety. The majority of Lanzhou Veolia Water Company is owned by the city government, while Veolia China, a subsidiary of Veolia Environnement, owns 45 percent of the company, Reuters said.

A preliminary investigation suggested that the benzene may have originated from petrochemical plants located in the vicinity of the Yellow River. Lanzhou Deputy Mayor Yan Zhijian confirmed that the contamination was caused by a leak in a crude oil pipeline carrying crude to petrochemical facilities in the industrial area of the city.