81
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15. Whenever a reduction of fall, (below the standard grade 1 in 30), is necessary or permissible, it shall, wherever practicable, be made in the portion of the drain nearest to the outlet, rather than in the part nearest to the inlet and in the main trunk of the drain, rather than in the branches.
16. Whenever the gradient of any portion of a drain is less than one in thirty, the Sanitary Board may in its discretion require an automatic flush tank or any other suitable contrivance for attaining an effective flush to be used.
17. All changes of direction in house-drains shall be made by means of properly curved pipes or by half channels in manholes and between the points at which any change of direction occurs all house-drains shall be laid in straight lines and regular grades from point to point.
NOTE.—(Inasmuch as changes of direction are the points at which obstructions most frequently occur, and for the purpose of removing obstructions generally, house-holders will do well to provide, at each change of direction, a manhole, giving access to the drain. For this purpose the manhole should be made 3'0" x 1'6" to the surface or to a depth of five feet above the drain. Beyond this depth the manhole may be narrowed to 1'6" x 1'6"). But such manhole should not be found in cook-houses or in places where they may be opened and used as receptacles for the disposal of solid rubbish.
Ventilation.
D AM
18. Whenever a house-drain runs under a building, or whenever it traverses soft or yielding ground, or where water may make its appearance in the trench, it shall be surrounded throughout its entire length with four inches of good concrete.
The stones composing the matrix of the concrete shall be of a size to pass through a half-inch ring.
19. No new drain shall be constructed in such manner as to allow any inlet to such drain to be placed inside any building on such premises.
20. The aggregate area of the openings in any grating fixed on inlets to waste-pipes from baths or sinks shall not be less than four square inches and the waste-pipe shall not have a less internal diameter than 1½ inches.
NOTE—The object of this is to secure an efficient flush.
21. Traps or gulleys for the removal of rain-water shall be provided with gratings having the nett area of the openings not less than twice the area of the trap or pipe. Such gratings shall be sunk to a depth of at least one inch below the surrounding pavement, with a slope round them equal to half the width of the grating.
NOTE. It is not sufficient to provide pipes of ample diameter; there must be openings of sufficient size to admit the rain to them.
22. Traps at the inlets to drains shall be placed so that the water-level in them is not less than one foot below the ground, and such trap shall be placed as low down as the level of the house-drain or branch will permit of; provided that the depth be not more than two feet.
23. Traps shall have not less than two inches of water seal and shall be securely fixed to the drain. All stoneware traps shall be surrounded with a thickness of four inches of lime concrete.
24. No person shall construct or fix in connexion with any new drain or waste pipe the form of trap of the kind known as the Bell-Trap or any trap of the kind known as the D trap and all traps connected with any private drains shall be properly set in cement mortar to the satisfaction of the Board.
NOTE.—Bell-Traps and D traps from their form give rise to deposit of filth difficult to remove by flushing.
Ventilating pipes.
Down-pipes.
Waste-pipes.
Waste-pipes.
Rain-water pipes.
Form of Traps.
25. Every main house-drain, wherever practicable, shall be ventilated at its upper end by an opening in free communication with the outer air. This opening shall be placed in such a position as to render any emanations from it as little obnoxious as possible.
NOTE. (This is, in most cases, to be done by carrying up a well-jointed pipe, not less than four inches in clear internal diameter, to some point above the eaves of the building, which is not in close proximity to any window or chimney. In the case of rural or suburban tenements, the ventilating opening may be provided on any eminence or open space at a distance from the dwelling; the ventilating pipe and opening, in this case, being not less than four inches in internal diameter.)
Covering up drains.
26. Every main house-drain shall have a ventilating opening near to its lower end and no trap or other obstruction to the free circulation of air shall exist between this opening and the one described in the preceding bye-law.
If there be a trap between the house-drain and the public sewer, then an opening shall be made on the house-side of the trap, and the said opening shall be so arranged as to give access to the trap for inspection, cleansing or repair.
If there be no trap between the public sewer and the house-drain no special opening need be provided at the lower end.
27. Drains leading from a single trap and not being more than sixty feet long need not be provided with an elevated ventilating opening at their upper end but if this be omitted, they shall be provided with a trap, disconnecting them from the public sewer, and shall have a ventilating opening at the lower end on the house-side of the trap.
28. Ventilating and fall pipes of stoneware shall be securely fixed to the exterior surfaces of walls with wrought iron bands fitted round the pipe and made fast to the wall with two wrought iron spikes not less than four inches in length. Metal pipes shall also be fixed as above or shall have two ears fixed to them and secured to the wall with two wrought iron spikes, not less than four inches long.
29. Down-pipes, conveying rain-water from roofs, shall be constructed of cast or welded wrought-iron, and when the down-pipe discharges into the house-drain it shall be completely disconnected therefrom, as described in bye-law No. 31 and fitted with a bend, shoe or pedestal pipe. Wherever practicable, the rain-water down-pipes on the street side of buildings shall be carried under the footpath and discharge into the side-channel.
NOTE.—It is most important that such pipes should be completely disconnected from the sewers so that they cannot by any possibility serve as conduits for conducting sewer air up and into the dwelling.
30. Waste-pipes from baths, sinks and other similar appliances, on the upper floors of buildings shall be of cast-iron socketed pipes or wrought-iron welded-pipes with screwed joints coated with bituminous composition, or in the case of wrought-iron, galvanised; or of well-glazed stoneware socketed pipes, or other approved materials, securely fixed outside the wall, and provided, at each point of connection, with a suitable head, and at their lower extremity with a bend, shoe or pedestal pipe. All joints of stoneware pipes to be made in the manner provided for in bye-law 5.
NOTE—Zinc, tin-plate, rivetted or lap-jointed sheet-iron will not be approved.
31. Waste-pipes, as well as down-pipes from roofs, shall not be connected direct with any drain but shall discharge in the open air near to or over a trap and they shall be brought down to within at least one foot of the ground.
32. No rain water-pipe from the roof of a building shall be used as a ventilating shaft to any drain which communicates or is designed to communicate with a public sewer.
NOTE. Rain water-pipes terminate at the eaves of the house a point not high enough above windows to be a safe ventilating outlet.
33. Any person who may have laid any new drain or constructed new drainage works connected therewith shall not cover up such drain or works until the same shall have been previously inspected and passed by the Board, and such person shall give three clear days' written notice to the Board that such drain or works are ready for inspection, and such notice shall be delivered at the Office of the Board in a form of which printed blank copies may be obtained gratis in English and Chinese on application at the Office of the Board, or in the case of Villages—at any Village Police Station, between the hours of 10 a.m. and 4 p.m.
81
f
15. Whenever a reduction of fall, (below the standard grade 1 in 30), is Fall to drains. necessary or permissible, it shall, wherever practicable, be made in the portion of the drain, nearest to the outlet, rather than in the part nearest to the inlet and in the main trunk of the drain, rather than in the branches.
16. Whenever the gradient of any portion of a drain is less than one in thirty, Fall to drains and flush. the Sanitary Board may in its discretion require an automatic flush tank or any
other suitable contrivance for attaining an effective flush to be used.
17. All changes of direction in house-drains shall be made by means of properly Change of direction. curved pipes or by half channels in manholes and between the points at which any change of direction occurs all house-drains shall be laid in straight lines and regular grades from point to point.
NOTE.-(Inasmuch as changes of direction are the points at which obstructions most frequently occur, and for the purpose of removing obstractions generally, house-holders will do well to provide, at each change of direc- tion, a manhole, giving access to the drain. For this purpose the manhole should be made 3'0" x 16" to the surface or to a depth of five feet above the drain. Beyond this depth the manhole may be narrowed to 1' 6" x 1′6′′). But such manhole should not be found in cook-houses or in places where they may be opened and used as receptacles for the disposal of solid rubbish.
Ventilation.
Ventilation.
D
AM
18. Whenever a house-drain runs under a building, or whenever it traverses Drains under buildings, &c. soft or yielding ground, or where water may make its appearance in the trench
it shall be surrounded throughout its entire length with four inches of good con-
crete.
The stones composing the matrix of the concrete shall be of a size to
pass through a half-inch ring.
19. No new drain shall be constructed in such manner as to allow any Inlets. inlet to such drain to be placed inside any building on such premises.
20. The aggregate area of the openings in any grating fixed on inlets to waste- size of openings in grat- pipes from baths or sinks shall not be less than four square inches and the waste- ings. pipe shall not have a less internal diameter than 11⁄2 inches.
NOTE-The object of this is to secure an efficient flush.
21. Traps or gulleys for the removal of rain-water shall be provided with Traps. gratings having the nett area of the openings not less than twice the area of the trap or pipe. Such gratings shall be sunk to a depth of at least one inch below the surrounding pavement, with a slope round them equal to half the width of the grating.
NOTE. It is not sufficient to provide pipes of ample diameter there must be openings of sufficient size to admit the rain to them.
22. Traps at the inlets to drains shall be placed so that the water-level in Traps. them, is not less than one foot below the ground, and such trap shall be placed as low down as the level of the house-drain or branch will permit of; provided that the depth be not more than two feet.
23. Traps shall have not less than two inches of water seal and shall be Traps. securely fixed to the drain. All stoneware traps shall be surrounded with a
thickness of four inches of lime concrete.
24. No person shall construct or fix in connexion with any new drain or waste pipe the form of trap of the kind known as the Bell-Trap or any trap of the kind known as the D trap and all traps connected with any private drains shall be properly set in cement mortar to the satisfaction of the Board.
NOTE.-Bell-Traps and D traps from their form give rise to deposit of filth difficult to remove by flushing.
Ventilating.pipes.
Down-pipes.
Waste-pipes.
Waste-pipes.
Rain-water pipes.
Form of Traps.
25. Every main house-train, wherever practicable, shall be ventilated at its Ventilation upper end by an opening, in free communication with the outer air. This opening shall be placed in such a position, as to render any emanations from it as little obnoxious as possible.
NOTE. (This is, in most cases, to be done by carrying up a well-jointed pipe, not less than four inches in clear internal diameter, to some point, above the eaves of the building, which is not in close proximity to any window chimney. In the case of rural or suburban tenemente, the ventilating opening may be provided on any eminence, open space at a distance from the dwelling; the ventilating pipe and opening, in this case, being not less th four inches in internal diameter.)
Covering up drains.
26. Every main house-drain shall have a ventilating opening near to its lower end and no trap or other obstruction to the free circulation of air shall exist between this opening and the one described in the preceding bye-law.
If there be a trap between the house-drain and the public sewer, then an opening shall be made on the house-side of the trap, and the said opening shall be so arranged as to give access to the trap for inspection, cleansing or repair.
If there be no trap between the public sewer and the house-drain no special opening need be provided at the lower end.
27. Drains leading from a single trap and not being more than sixty feet long, need not be provided with an elevated ventilating opening at their upper end but if this be omitted, they shall be provided with a trap, disconnecting them from the public sewer, and shall have a ventilating opening at the lower end on the house- side of the trap.
28. Ventilating and fall pipes of stoneware shall be securely fixed to the exterior surfaces of walls with wrought iron bands fitted round the pipe and made fast to the wall with two wrought iron spikes not less than four inches in length. Metal pipes shall also be fixed as above or shall have two ears fixed to them and secured to the wall with two wrought iron spikes, not less than four inches long.
29. Down-pipes, conveying rain-water from roofs, shall be constructed of cast or welded wrought-iron, and when the down-pipe discharges into the house- drain it shall be completely disconnected therefrom, as described in bye-law No. 31 and fitted with a bend, shoe or pedestal pipe. Wherever practicable, the rain-water down-pipes on the street side of buildings, shall be carried under the footpath and discharge into the side-channel.
NOTE.-It is most important that such pipes should be completely disconnected from the sewers so that they cannot by any possibility serve as conduits for conducting sewer air up and into the dwelling.
30. Waste-pipes from baths, sinks and other similar appliances, on the upper floors of buildings shall be of cast-iron socketted pipes or wrought-iron welded- pipes with screwed joints coated with bituminous composition, or in the case of wrought-iron, galvanised; or of well glazed stone-ware socketted pipes, or other approved materials, securely fixed outside the wall, and provided, at each point of connection, with a suitable head, and at their lower extremity with a bend, shoe or pedestal pipe. All joints of stoneware pipes to he made in the manuer provided for in bye-law 5.
NOTE-Zine, tin-plate, rivetted or lap-jointed sheet-iron will not be approved.
31. Waste-pipes, as well as down-pipes from roofs, shall not be connected direct with any drain but shall discharge in the open air near to or over a trap and they shall be brought down to within at least one foot of the ground.
32. No rain water-pipe from the roof of a building shall be used as a ventila. ting shaft to any drain which communicates or is designed to communicate with a public sewer.
NOTE. Rain water-pipes torminate at the eaves of the house a point not high enough above windows to be a safe ventilating outlet.
33. Any person who may have laid any new drain or constructed new drainage works connected therewith shall not cover up such drain or works until the same shall have been previously inspected and passed by the Board, and such person shall give three clear days' written notice to the Board that such drain or works are ready for inspection, and such notice shall be delivered at the Office of the Board in a form of which printed blank copies may be obtained gratis in English and Chinese on application at the Office of the Board, or in the case of Villages-at any Village l'olice Station, between the hours of 10 a.m. and 4 P.M.
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