Drains outside of the house should be of vitrified or glazed earthenware pipe, laid below the action of frost, with proper slant. They should be well bedded and have smoothly cemented joints. The slant need be very slight, eighteen inches in eighty feet or less may be used. It is especially desirable that the joints be thoroughly cemented, and that they be smooth on the inside, so that the foul matter passing through the interior will not lodge against any projections. The surface or ends of the pipe should never be clipped or cut for connections; “Y’s” or “T’s” are used for all connections with other drains. Drain pipes from a dwelling-house are usually five or six inches in diameter. It is quite as important that they be not too large as that they be large enough. Where a pipe is too large, there is not enough water in the bottom to keep it clean. The illustration here given will make clear this point. A six and eight inch drain is shown with the same quantity of water in each. It is common in cases of drain connection with a vault that no trap in the drain or soil pipe itself be used. Where sewer connection is made, a vitrified trap of the same size as the drain is used; and it is provided with a trap vent connection with the outer air by means of vitrified vent and grate opening at the top.
Storm-water connections may be made with the main sewer, but it is best that they be made between the house and the trap of main drain. In this way there is no danger of the sewer having connection with the down spouts in the event of the evaporation of the water in the trap of the storm-water connection. The modern plan of city sewer systems is to have independent service for storm water and house drain connections.
GREASE SINKS.
The grease sink is lined with brick, and is usually of four or five barrels capacity. It is cemented the same as the cistern, is generally twenty or twenty-five feet away from the house, and has a four-inch vitrified drain connection with the waste from the kitchen sink or other sink in which greasy water may be deposited. The sink itself has a siphon connection with the main drain or vault, and, being provided with an iron top, the deposit of grease or other material may be removed if necessary. In some instances a sink of this kind is required to be used to collect all solid matter before the drainage connection passes from the property.
The “S” trap only has been distinctly mentioned. There are hundreds of others, all constructed upon the same general principle. Some are provided with mechanical means of closing the opening leading to the source of supply, and, in addition to this, they are provided with a seal of water depending upon some form or condition of the “S” trap. This principle is invariable in the construction of traps. No trap should be used unless provided with a trap screw of the same size as the drain itself, which will admit of its being opened when necessary. It is not uncommon that rings or other jewelry get into the waste of wash-stand or bath-tub; they may be recovered by taking out the trap screw. Again, should the trap become fouled or clogged, the matter may be removed in the same way.