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Frequently asked questions

Drainage Repair

You can ask the management office of your building to carry out an inspection to ascertain if there is any U-trap installed and carry out remedial works if necessary. Alternatively, you may employ a competent/experienced drainage/plumbing contractor to carry out the inspection and necessary remedial works.

If you have experienced a smell of foul air in your toilet there is a possibility that the U-trap is not functioning properly. The U-trap should be filled up with water to enable its proper functioning. You can check if there is any water left in the U-trap by dipping a stick into the fitment outlet to reach the trap to ascertain if the stick is wet.

If the drains or pipes of a private building are found to be defective, inadequate or insanitary, these may result in discharging of untreated sewage to open air, foul smell, water pollution, slippery surfaces, pest infestation, breeding of mosquitoes or other health and environmental hazards. Under such circumstances, Building Authority will adopt a "zero tolerance" approach and will invoke his power under section 28 of the Buildings Ordinance (Cap.123) to serve an order on the owners requiring them to carry out repairs within a certain period of time.

Examples of drainage defects are:

  • Waste pipes, soil pipes, rainwater pipes or ventilation pipes, including any hoppers and supporting brackets, are defective or in disrepair
  • illegally connected drain pipes discharging untreated sewage directly into open channels of rear lanes or streets or onto stormwater drains
  • defective manholes
  • defective or collapsed underground drains of private rear lanes causing choked drains and backflow of effluent onto the lanes

Building owners receiving drainage repair orders from Buildings Department should appoint a competent contractor to investigate the defects and carry out necessary repairs or replacement of the pipeworks, including any hoppers and supporting brackets, as necessary within the specified time. Failing to do so may result in Buildings Department's further enforcement action. Furthermore, the Building (Minor Works) Regulation has been implemented on 31 December 2010. Under the new Minor Works Control System (MWCS), any person intending to carry out minor works can follow the simplified procedures. For more details about MWCS, please call BD hotline 2626 1616 or BD's website - (

Building owners, owners' corporations or building management and maintenance personnel are encouraged to conduct regular inspection on the drainage system or sanitary fitments of their buildings to ensure that the same is properly maintained and in working condition. In this connection, Buildings Department has published a "Guidelines on Maintenance and Repair of Drainage System and Sanitary Fitments" to help owners. The guidelines is available from offices of Buildings Department and it can be downloaded from

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