New | China seeks solution to providing clean drinking water supplies

Large colonies of micro-organisms – some capable of causing serious disease – have been discovered inside pipelines carrying drinking water to homes in most major mainland cities, the South China Morning Post has learned.

Fortunately, most people in China habitually boil water before drinking, killing off the organisms and reducing the risk of outbreaks. But many foreign visitors are unaware of the issue and often drink from the tap.

Senior government officials and scientists met last year in Beijing to discuss potable water safety, industry insiders say. One possible solution would be to launch a national programme to replace pipes with higher-quality ones, made either of steel or plastic with specially treated coatings.

But such an effort would be costly and some experts question whether the central government would be prepared to commit sufficient resources to the funding. They also wonder if replacement is the most efficient solution.

Water safety on the mainland has come under scrutiny following a tap water scare in Lanzhou, Gansu province, last week. Benzene, which can cause cancer, was discovered in tap water at levels 20 times higher than national limits. An investigation continues, but lax supervision, the proximity of petrochemical facilities and corroded supply pipes have all been identified as possible causes.

Professor Guan Yuntao, associated with a laboratory in Shenzhen under the auspices of Tsinghua University, has been carrying out government-funded research on micro-organisms in urban water networks for several decades. The organisms, together with organic compounds and heavy metals, are the main contributors to unsafe drinking water. In some cities, membranes consisting of a variety of species can form on the inside surface of pipes – much like plaque build-up in human arteries – “in a matter of days”.