Rats are an important indication of defective drains. The presence of rats in a house should always lead to a thorough investigation of its drains.
[CHAPTER XXVI.]
CESSPOOLS AND MAIN SEWERS.
The terms Sewer and Drain are used somewhat confusedly. The term drain should be used to designate the pipes bringing the sewage from the house into the street-sewer, or any pipes by which the subsoil is drained; the term sewer being confined to the trunk canals into which the house drains empty their contents.
Where the water-carriage system of sewerage is adopted, involving the use of water-closets as described in the last chapter, the sewage may be carried from the house either into cesspools or into the main sewer.
Cesspools are only permissible in isolated country-houses supplied with water-closets. They should always be situated a considerable distance from the house, and should be emptied at regular intervals, the sewage being placed in shallow trenches on the land.
The construction of the cesspool requires careful attention. Its walls should be of brickwork set in cement, lined inside with cement, and surrounded by clay puddle. The bottom should have a fall towards one side, where a pump can be fixed, to remove the more liquid contents. The depth of the cesspool should never exceed 7 feet. The drain emptying into the cesspool should be trapped and ventilated, near its junction with the cesspool; and the cesspool itself should be ventilated.
In connection with many old houses in towns, cesspools still exist, sometimes under the basement or near the house, and so built as to allow soakage in every direction. The surrounding soil becomes contaminated for a considerable distance, the water in any neighbouring well is tainted, or leaky water-pipes receive the soakage. The cleansing of cesspools is always a disgusting process, and even dangerous to the workmen employed. They incur the risk of suffocation, and are very subject to ophthalmia. To avoid these dangers a pump and hose connected with a partially exhausted barrel is employed, but even with this provision some nuisance arises. In the Bexley cart, which is used for this purpose, a hose is used to connect the cesspool with an air-tight cylinder in the cart, into which the contents of the cesspool are pumped.
A modification of the cesspool system, called the Pneumatic System has been proposed by Captain Liernur. In it the cesspool is not placed under the house or the courtyard of the house, but under the street at the angle of junction of several streets. It is made of cast-iron and air-tight, and is connected with all the houses of several streets by iron pipes. By means of a powerful air-pump worked by steam, the cesspool is emptied into barrels in which it is sent directly to farms; and the barrels being placed on ploughs of peculiar construction, the manure is discharged from the bung-hole of each barrel and covered over with earth in the progress of the plough. The pipes tend in this and similar systems to get clogged with fæcal matter, and large quantities of water are required to keep them clean, so that the system merges into that of the use of water-closets, but without the thoroughness of the latter.
Cesspools have been almost improved out of existence in some continental towns, by the introduction of movable cesspools,—fosses mobiles,—to which would correspond strictly the tubs and pails used in some of our large towns. Such movable receptacles have been still further “improved” by the adoption of separators, by which the liquid parts are allowed to escape into the sewer, while the solid parts remain comparatively inoffensive. But when this is done, the cesspool may be as well abolished, as the foulness of the sewage is not greatly increased by allowing solid as well as liquid excreta to enter it.