In installing the Durham system, what course is followed regarding underground piping?

All underground piping must be of cast iron with calked joints, for the reason that the wrought iron or steel pipe rusts out so much more rapidly.

Is the use of lead increasing in favor?

Much of the best and largest work is now being installed without the use of any lead pipe whatever.

How may the water closet be installed without the use of lead bend?

By the use of a floor flange which either calks or screws into the soil pipe, and the use of cast iron fittings.

Why is the use of the ordinary leeching cesspool often to be looked upon with disfavor?

After a time the joints and crevices of the cesspool fill up with solid matter, and if there is no overflow to carry the liquid portion of the waste to a second cesspool, the cesspool overflows, saturates the surrounding soil, and in many ways becomes a nuisance.

How may a cesspool be constructed so that it shall have the advantages of both the water-tight and the leeching cesspool?

An excavation is first made of considerably greater dimensions than the cesspool itself. The bottom is filled in with a heavy foundation of broken stone, and upon this the brick cesspool with brick bottom is built. A considerable space should be left between the brick work and the excavated ground on all sides, this space being filled with broken stone. The brick cesspool is made water-tight by means of a coating of Portland cement inside. The top should be arched somewhat, and provided with a manhole cover. At a proper height overflow pipes should be cemented into the brick-work, all on the same level. The outer end of the overflows should terminate at the center of the broken stone filling. By means of the overflows, the liquid portion of the contents of the cesspool are carried off, and allowed to leech off through the surrounding soil, while the solid portion is retained in the cesspool, and may be emptied when desired. The solid matter should never be allowed to rise to such a point that it may pass out through the overflows or close them up.

Why should a cesspool not be located too low in the ground?

For the reason that the bacteria of the soil, which attack and disintegrate the impurities of the sewage, must have air to live upon, and the air does not reach them at levels far below the surface.

When there is no system of sewers to handle the sewage from a residence, institution, or from a number of dwellings, how may this work usually be accomplished?

By means of a septic sewage tank for receiving the waste, in connection with an automatic sewage syphon, by means of which the contents of the septic tank are siphoned off onto filter beds, into a system of underground filtration, or other means of final disposal.

Give a general description of the construction and operation of the septic tank.

As generally constructed it consists of three or more separate compartments, the plant being located underground usually. The sewage is delivered directly into what is known as the grit chamber, which connects by overflow with one or more settling chambers. Most of the solid matter remains in the grit chamber, the liquid overflowing into the settling chamber or chambers, and becoming clearer in each successive compartment. From the last settling chamber it overflows into the discharge chamber, connected to which is an automatic sewage syphon. (See page 113.)