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34. All surfaces of backyards and paved areas of premises wherever practicable shall have a fall towards the trap or inlet of the drain of not less than 1 in 40, and such inlet shall be placed as far from the walls as practicable.
35. Open surfaces such as backyards, courtyards or other spaces on which slops are thrown, or from which foul water flow, shall be provided with trapped connexions to the covered drains for the re- moval of such waters as well as some of the rain-water.
36. Wherever an outlet is available, surface channels shall be provided to carry excessive rainfall from the premises, and these channels shall be properly connected with a storm water-channel or drain. As many four inch traps as the Building Authority may approve shall be placed in such surface channels and connected with the covered drains for the purpose of flushing the sewers.
37. The rain-water from roofs which slope towards inclosed courtyards or backyards may, if diversion to the surface channel is impracticable, be received into the covered drains, but no ventilat- ing pipe shall be used for the conveyance of rain-water from the roof.
38. No person shall, where it can possibly be avoided, lay any pipe for conveying sub-soil drainage in such manner or in such position as to communicate directly with any sewer, cesspool, or covered drain used for the conveyance or reception of sewage.
39. In every case where the course of a drain or sewer shall be diverted, any cesspool previously existing and into which such drain or sewer may have previously emptied, shall be cleansed, deo- dorized and filled with clean earth.
40. Every water-closet and urinal in a building shall, unless exempted by the Building Authority, be constructed against an external wall, and all apparatus shall be fixed as near to such external wall as in the opinion of the Building Authority is practicable.
41. Every water closet and urinal shall be furnished with a separate cistern or flushing box unless the Building Authority shall otherwise permit. In the case of water closets such cistern or flush- ing box shall be so constructed, fitted and placed as to admit of a supply of water to such closet, basin, or other receptacle of not less than two gallons and not more than three gallons each time such basin or other receptacle is used.
Such cistern or flushing box shall in all cases, except where it is in connexion with a valve-closet, be of the type known as Water Waste Preventor.
Such cistern shall be provided with a suitable ball-cock fixed on the supply pipe, and it shall be furnished with an overflow pipe carried through the external wall of the building into the open air and terminating in a conspicuous place.
Provided that, in the case of trough water closets and urinals, such cistern or flushing box shall be of automatic action and of such size and pattern and discharging at such intervals as may be ap- proved by the Building Authority.
42. Every water closet and urinal shall be furnished with a suitable apparatus for the effectual application of water to any basin, or other receptacle with which such apparatus may be connected and used, and for the effectual flushing and cleansing of such basın or other receptacle, and for the prompt and effectual removal there from of any solid or liquid filth which may from time to time be deposited therein.
Every water closet or urinal shall be furnished with a basin or other suitable receptable or receptacles of non-absorbent material, and of such shape, capacity, and mode of construction as to receive a sufficient quantity of water; and every such receptacle in con- nexion with a water closet shall in addition contain a sufficient quantity of water to allow of all filth which may from time to time be deposited therein to fall directly into the water. Every such receptacle shall be provided with a suitable trap, having a water seal of not less than one and a half inches..
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