### Building (Standards of Sanitary Fitments, Plumbing, Drainage Works and Latrines) Regulations 《建築物(衞生設備標準、水管裝置、排水工程及廁所)規例》

27. Waste pipes
(1) Waste pipes to which the waste from one waste fitment is discharged shall have an internal diameter of not less than— (E.R. 3 of 2020)
(a) 32 mm; or (L.N. 294 of 1976)
(b) the internal diameter of the outlet of the trap to which the waste pipe is connected,
whichever is the greater.
(2) Waste pipes to which the waste from more than one fitment is discharged shall be of adequate diameter to convey all such waste.
(3) Every waste pipe shall terminate at its lower end not more than 150 mm above the channel or trapped gully over or into which it discharges. (L.N. 294 of 1976)

28. Bends in soil and waste pipes
(1) Soil pipes and waste pipes shall not have bends therein, except where unavoidable.
(2) Whenever a bend is unavoidable—
(a) the bend shall—
(i) have an obtuse angle;
(ii) have the largest practicable radius of curvature; and
(iii) not change in any way the cross section of the pipe; and
(b) a cleaning eye or other suitable means of access shall be provided at or near the bend.

29. Access to soil and waste pipes
(1) Sufficient access shall be provided, by means of cleaning eyes or other approved method, to enable soil pipes and waste pipes to be cleared of any obstruction.
(2) Such access points shall be so sited as to allow clearance for the easy entry of cleaning rods.

### Building (Standards of Sanitary Fitments, Plumbing, Drainage Works and Latrines) Regulations 《建築物(衞生設備標準、水管裝置、排水工程及廁所)規例》

30. Anti-syphonage pipes
(1) Where—
(a) more than one trap of a watercloset fitment, urinal, slop sink or waste fitment is connected with one soil pipe; or
(b) more than one trap of a waste fitment is connected with one waste pipe,
the traps shall be ventilated by means of anti-syphonage pipes:
Provided that if, in the case of waste fitments, the traps to such fitments are constructed to prevent loss of water seal, it shall not be necessary to provide an anti-syphonage pipe, unless the Building Authority so requires.(2) Every anti-syphonage pipe shall be connected with—
(a) the trap, if the connexion with the anti-syphonage pipe is an integral part of the trap; or
(b) the branch soil pipe or branch waste pipe—
(i) on the side of the water seal nearest the main soil pipe or waste pipe; and
(ii) at a point not more than 300 mm from the trap outlet. (L.N. 294 of 1976)
(3) The internal diameter of every anti-syphonage pipe shall—
(a) if the diameter of the soil pipe or waste pipe to which it is connected is 80 mm or more, be not less than 50 mm;
(b) if the diameter of such soil pipe or waste pipe is less than 80 mm, be not less than—
(i) two-thirds of the internal diameter of such soil pipe or waste pipe; or
(ii) 32 mm,
whichever is the greater. (L.N. 294 of 1976)
(4) (a) The main anti-syphonage pipe may be connected to a soil pipe which, under regulation 31(3), is acting as a ventilating pipe.
(b) Every such connexion shall be made at a point above the flood level of the highest fitment connected to the soil pipe. (E.R. 3 of 2020)

### Building (Standards of Sanitary Fitments, Plumbing, Drainage Works and Latrines) Regulations 《建築物(衞生設備標準、水管裝置、排水工程及廁所)規例》

31. Ventilating pipes
(1) Every ventilating pipe for any drain or sewer shall be carried up to a height not less than 1 m above the roof of the building to which it is fixed or, where such building has a pitched roof, above the eaves of such building. (L.N. 294 of 1976)
(2) No ventilating pipe shall be so fixed as to permit the escape of foul air from any drain, sewer, soil pipe or waste pipe into any building.
(3) Soil pipes or waste pipes may be carried up to a suitable height above the building to which they are fixed to act as ventilating pipes for any drain or sewer.
(4) The internal diameter of every ventilating pipe and of every soil pipe or waste pipe which, under paragraph (3), is acting as a ventilating pipe, shall be not less than 80 mm. (L.N. 294 of 1976)
(5) The open end of every ventilating pipe shall be provided with a suitable grating having apertures of an aggregate area not less than the sectional area of the pipe.
(6) Ventilating pipes shall not be used for the carriage of surface water.

### Building (Standards of Sanitary Fitments, Plumbing, Drainage Works and Latrines) Regulations 《建築物(衞生設備標準、水管裝置、排水工程及廁所)規例》

32. Rain water pipes
(1) (a) Every rain water pipe which discharges to a drain which is connected to a public sewer provided for the carriage of surface water shall—
(i) in the case of a rain water pipe situated outside a building, discharge either not more than 150 mm above the level of the ground over a suitably trapped gully or into a trapped gully below the level of the grating but above the level of the water in the trap; and
(ii) in the case of a rain water pipe situated inside a building (other than a rain water pipe used solely for the conveyance of rain water from a roof), be properly trapped with an efficient trap which shall be so formed and fixed as to maintain a water seal of not less than 75 mm. (L.N. 62 of 1966; L.N. 361 of 1980)
(b) Every rain water pipe which discharges to a channel shall discharge at a height not more than 150 mm above the level of the top of the channel.
(c) Every rain water pipe which discharges, through a cast iron conductor, to the side channel in a street shall be provided, at the foot thereof, with a shoe so as to ensure that any surface water discharged from the pipe will discharge directly into the conductor.
(2) The number and size of rain water pipes provided for any building shall be calculated at the rate of 700 mm2 of pipe to every 10 m2 of horizontal roofed-over surface.
(3) Save as provided in regulation 33, the diameter of every rain water pipe shall be not less than 65 mm.
(4) Rain water pipes shall not be connected with any soil pipe, waste pipe or ventilating pipe.
(5) Where a rain water pipe discharges, across any footpath, to the side channel of a street, it shall discharge through a cast iron conductor.
(L.N. 294 of 1976)

33. Rain water pipes for verandahs or balconies
(1) Any rain water pipe provided for the carriage of surface water from a verandah or balcony shall, where there is, at a suitable position, a rain water pipe provided for the carriage of surface water from the roof of the building, be connected to such pipe.
(2) Where a rain water pipe provided for the carriage of surface water from a verandah or balcony discharges to the side channel in a street or is, in accordance with paragraph (1), connected to a rain water pipe which so discharges, the internal diameter of the rain water pipe from the verandah or balcony shall be not more than 40 mm. (L.N. 294 of 1976)