A lawmaker and an engineer have urged the government to consider launching a large-scale water pipe replacement scheme and quickly, following a serious water main burst in Lai Chi Kok on Sunday. A taxi driver was injured when his vehicle plunged into a sinkhole due to the burst. A passenger managed to get out unscathed. Legislator Yang Wing-kit said a scheme between 2000 and 2015 which saw repairs to 3,000 kilometres of old pipes led to big improvements when it comes to bursts, with the number of incidents dropping from around 2,500 a year to under 40. But he told RTHK that workers should now be more proactive and shouldn't wait for bursts to happen before checking whether pipes need to be repaired or replaced. "After all, water pipes have a limited life span. The government's been repairing water pipes since the year 2000, but it's been more than 20 years. Even the replaced pipes have gradually started to age," he said. "And there are some 5,000 kilometres of pipes that haven't been replaced... There should be a new replacement scheme to prevent the problem of mains bursts." Yang added that the authorities could consider using robots to check pipe conditions. Aaron Bok, a former president of the Institution of Engineers, said the water main in Lai Chi Kok that burst involved iron pipes laid some 60 years ago. He said such pipes now make up less than three percent of the total across Hong Kong and they should be replaced as soon as possible. "We describe these iron pipes as rather brittle. When they're damaged, they burst quicker, unlike pipes made of other materials where you'd see some seepage first," Bok said. "When the iron pipes burst, water gushes out with a bang, damaging roads and eroding underground soil. So the [affected] area is big." Bok, who spent nearly four decades in government before retiring three years ago, added that the Water Supplies Department's monitoring of pipes follows international standards.
