153. Sewage matter from buildings is disposed of in various ways, but chiefly by the following methods:

1. By a connection to the main or street sewer pipe or culvert.

2. By cesspools.

3. By direct or indirect discharge to the sea or rivers in close proximity to the building.

The first method is always adopted in well regulated cities having a system of sewage. For an ordinary residence, the pipe leading to the street sewer, called the sewer connection, is generally 6 inches in diameter, and is made of vitrified or salt-glazed fireclay spigot and socket pipes. It should be laid in a straight line between the disconnecting trap in the cellar and the street sewer. A handhole should be attached to the pipe in the cellar, so that in case of chokage, iron rods can be run through to the street sewer. The point at which this pipe joins the sewer should, if possible, be sufficiently high up the sides that the sewage cannot at any time back up in the sewer connections. The question of the disposal of sewage matter from buildings which are located in small country towns having no sewer system, is sometimes a difficult one, especially when the water supply is taken from wells.

154. Cesspools are commonly used to receive the filth from sinks and privies; but they are so liable to foul the soil for many yards in every direction, to pollute the air, and to poison all the wells in the vicinity, that they should never be employed if they can be avoided.

It seems almost incredible that rational people should deposit their slops and excreta in a pit which is dug in the same stratum of earth which contains the well from which they take their drinking water; yet, this is one of the commonest hygienic crimes perpetrated in rural communities. The frequent epidemics of typhoid fever, diphtheria, and scarlet fever, which have resulted from this practice, have led the State Boards of Health, in many states, to prescribe that no cesspool or privy vault shall be built or maintained within 150 feet of a well which furnishes water for drinking or cooking purposes. Even this distance is so unsafe that the local Boards of Health are empowered, in many states, to forbid them altogether if they think best.

If the ground is composed of gravel or loose stones, or coarse sand, the cesspool is generally built of loose stones without mortar, so that the water may filter away and leave the solid matter behind. The joints of the stones, however, soon become clogged with soap and grease, if the grease is not intercepted before reaching the cesspool, and the filtration is stopped. The cesspool then fills up and overflows.

If the ground is of a clayey nature, and no other method of disposal can be had, the cesspool will, of course, fill up, and it must be pumped out when full; the matter pumped out may be used as a fertilizer.

The cesspool should be dug as far as possible from the building, and should not upon any account be near a well, neither should the drain pipe leading to the cesspool be run near a well.

Cesspools should not be built air-tight, but should have a vent pipe discharging at a safe and proper distance from the house. A running trap also should be placed on the drain pipe near the cesspool, having a fresh-air inlet and vent cap attached, so that a constant current of fresh air may pass through the drain.

Filtration is a most unsatisfactory procedure. The glutinous sludge soon chokes every description of filter.

155. If the sewage be discharged into a river or the sea, the outlet end should, if possible, be above high-water mark, so that high tides or rising of the river will not cause the water to flow up the sewer and perhaps choke it by backing up the solid matter. If the outlet must be below water mark, it should have a light brass flap valve attached to prevent fish, etc. from entering the pipe. It should also have a relief or vent pipe attached at a convenient point, to let out the air when a volume of water is passing down the drain-or when water backs up.

Crude sewage should not be discharged into rivers or streams whose velocities are low and volumes small, or where the velocity decreases between the point of sewage discharge and the mouth of the river, such, for example, as a deep or wide pool or dam in the river. As soon as quiet water is reached, the sewage matter will deposit there, putrefy, and pollute the river.

Neither should the crude sewage discharge into the sea at points where natural currents cannot be obtained to carry the solids seaward; because, if such a current cannot be obtained, the solid matter will be floated upon the beach and become a nuisance; or it will accumulate in mud banks and evolve offensive odors when agitated. The chief trouble to be found in discharging drains and sewers into the sea is that the sewage is backed up into the sewer twice in 24 hours. This is caused by the ebb and flow of the tide, and necessitates a good flush when the tide is low. The same trouble is experienced with tidal rivers.

156. By the irrigation method the sewage is conveyed to a tract of land composed of sand or light loam, if possible, where it is spread over or through the ground and constitutes the food of vegetation so far as derived from the soil.

There are many varieties of chemical treatments of sewage, but it is not within the limits of this section to treat of any of them. The motive for chemical treatment is to convert the sewage into a fertilizer, or otherwise dispose of it.

157. The use of the dry earth closet in place of privy vaults for the disposal of human excreta, is rapidly extending among the more intelligent class of people. In this apparatus the excreta are covered with dry earth, preferably loam, or with the sittings of anthracite coal ashes. The ashes from bituminous coal are worthless for this purpose.

The quantity to be used on each occasion is about one quart, which is usually enough to absorb all of the liquids, and to neutralize all of the odors. The accumulations are received in pails, and are carried away at intervals to the garden or meadows as fertilizers. The sanitary advantages of this system are so great that it is likely to come into general use for outdoor closets for country homes.