Prince Philip Dental Hospital used contaminated water, documents show

Hong Kong's dental teaching hospital may have given patients "heavily contaminated" water to rinse their mouths, despite staff knowing it had been tainted with bacteria, the South China Morning Post can reveal.

Internal documents from Prince Philip Dental Hospital in Sai Ying Pun, run by the University of Hong Kong and popular for its low-cost treatment, showed one of its five clinics had been tainted with bacteria.

It used the fouled water for four months this year, until it found a means of disinfection. Prince Philip Dental admitted to the Post that the contamination had occurred, but declined to specify bacteria levels or whether any patients had been affected.

Hospital chairman Sigmund Leung Sai-man promised a more detailed investigation.

"No patient has reported sick after oral treatment so far," Leung said. "It should be safe if patients did not swallow the water."

But microbiologist Dr Ho Pak-leung, of the University of Hong Kong, said people with weak immune systems were vulnerable to high levels of bacteria.

The papers showed that from mid-February to mid-June, water samples from the clinic exceeded 500 colony-forming bacterial units per millilitre - the US safe standard for drinking water.