By Edith Lin
Copyright scmp
Authorities have found bitumen in the freshwater supply of a Hong Kong subsidised estate, tracing the source of the sediments from a public pipe that underwent inspection last week.
The Water Supplies Department said on Thursday that it was alerted to the incident by the property management office of Kam Chun Court in Ma On Shan, involving blocks C, D and E.
Officers were deployed to collect and test water samples at the relevant flats and freshwater tanks in the buildings.
“The results show that all water samples comply with Hong Kong’s drinking water standards … After testing, the black particles were found to be bitumen, which is inert and not harmful to humans,” the department said on its social media page.
“We believe the particles resulted from a diversion of the water supply on September 12 to facilitate an inspection of an upstream public water main.
“During the process, the increased water pressure stirred up a small amount of sediment in the relevant service reservoir, prompting bitumen particles to enter the buildings’ internal water supply systems over the past few days.”
The department said it strengthened the filtration capability of the water pipes in the three blocks on Wednesday, which could block substances larger than 0.1mm in diameter.
It also deployed officers to the estate on Thursday to clean water meters for residents in need, while the estate’s property management would also wash all the freshwater tanks and internal pipes on Thursday and Friday.
According to the department, after implementing such procedures, its customer inquiry centres received six reports on Thursday, as of noon, down from the 30 cases on Wednesday.
The department added that it installed filters, which could block substances larger than 0.1mm (0.004 inches) in diameter, at pipes in Blocks A and B in June. Neither building was affected by the latest incident.
It said it would continue to monitor the estate’s water quality, including testing samples, and work with the property management, district councillors and residents.
The department advised residents that before using water they should run the tap for a while, especially when the water had been in the pipes for a while or first thing in the morning, until it becomes clear.
In May, Queens Hill Estate and Shan Lai Court in Fanling also reported bitumen particles in the freshwater supply. Authorities had to replace the water pipes that were believed to have brought sediments to the estates, among other follow-up actions.
