Tai Kok Tsui Drain Services

According to an HK01 report of 17 July 2017, during major repairs at Phase 2 of Fu Tor Loy Sun Chuen, built in the 1980s, the building "repeatedly suffered flooding, seepage and even sewage backflow", and the estate's management supervisor said complaints of backflow came regularly from owners on the second and third floors. That location is no accident: by inference from the design of the period, low-floor fitments may tee straight into the stack, so once the lower part of the stack narrows, the toilets and floor drains on the low floors are the first to rise when the floors above discharge. If several outlets on a low floor back up together, tell the management office or owners' corporation at once so the shared stack can be checked; if only one fitment is slow, it is more often the flat's own branch pipe, which you can arrange to have cleared directly.

The Buildings Department's Mandatory Building Inspection Scheme covers private buildings aged 30 or more, other than domestic buildings of not more than three storeys: once a statutory notice is served, the owners must appoint a registered inspector to carry out a prescribed inspection, and a registered contractor to complete any prescribed repair under that inspector's supervision. The drainage system is itself one of the items inspected — the Code of Practice for the scheme provides that the scope covers the drainage system at the external walls, the drainage system in the common parts, pipes laid within common pipe ducts, and the underground and above-ground common drainage system, with anti-syphonage and ventilating pipes included. The Code also requires the inspector to identify and report misconnections to the department, such as foul water discharging into the surface water drainage system. For common exposed pipes or pipe ducts that sit inside private premises, it allows access from a flat at least every three floors, or a CCTV survey instead, so not every door has to be knocked on. Several of Tai Kok Tsui's older blocks are long past the threshold: Cosmopolitan Estates was built in 1974–76 and Fu Tor Loy Sun Chuen in 1980–81, while Charming Garden, completed in 1998, does not reach 30 years until 2028. The practical point for owners is this: a statutory notice means scaffolding on the external wall in any case, so having the external pipes, hopper heads and joints dealt with in that same contract costs far less than scaffolding again later for a few lengths of pipe.

According to an HK01 report of 26 January 2021, the Democratic Party inspected ten districts between 22 and 24 January that month, including the Yau Tsim Mong restricted zones, looked at the drainage systems of about 200 buildings and "found that about 70 per cent had various problems with their external pipes", among them old pipes weeping and dripping, vent pipes altered or cut off, soil and waste pipes wrongly cross-connected, and the use of open hopper heads; the report also quoted a district councillor as saying that a building in Tai Kok Tsui had pipework that had come apart. What these have in common is that the fault is in the shared external pipework, not inside your flat. From a safe position, photograph the external and back-lane pipes — hoppers, rust stains, cracks, loose brackets, anything still dripping in dry weather — and pass it to the owners' corporation or owners' group. Altering a trap or an anti-syphonage pipe is minor works under the Buildings Department's control system and must be done by a registered minor works contractor.

A government press release of 18 March 2024 stated that, to implement the "single site, multiple use" initiative, the Drainage Services Department "has enhanced the rooftop of the dry weather flow interceptor at the Cherry Street box culvert in Tai Kok Tsui as a public open area", and that an approximately 85-metre-long extension of the Hoi Fai Road Promenade opened in December 2023. In other words, a box culvert runs beneath Cherry Street to the waterfront, and a dry-weather flow interceptor near the Hoi Fai Road end catches polluted flow in dry weather. Both of these spots are on the department's list of locations prone to blockage: Cherry Street (westbound) near Sham Mong Road, and the Cherry Street Underpass (westbound) near Lin Cheung Road. Two points matter for residents: whether the street is ponding and whether your flat is backing up are two independent clues — note the times separately and they can be matched up afterwards; and if a stormwater outlet still runs with sewage, or shows toilet paper, in dry weather, suspect a soil pipe wrongly connected into the stormwater system. That is shared pipework, for the owners' corporation or the department to take up.

One misunderstanding is common in both the older and the newer blocks here: water dripping from above, or a damp ceiling, is assumed to mean a blocked drain. A burst or leaking flushing-water (salt water) pipe to a cistern, or a fresh-water pipe, is a supply problem for a plumber and a closed stopcock, not drain work; odour, slow draining and water welling up at an outlet are drain problems. On the other side, when flushing water is cut off, or a bathroom goes unused for a long stretch, the trap seal evaporates and sewer air comes back through the floor drain — the Buildings Department advises pouring about half a litre of water into every floor drain at home at least once a week. Moving in, letting a flat out, or a water shut-off in the estate are all good moments to pour water into each outlet and test it.