There are several methods of disposing of sewage. In cities, or in any densely populated areas, the drain pipes from the house run into a community sewer pipe which brings the sewage to a disposal plant for treatment to render it harmless. In this case, the homeowner is only concerned with the pipe from the house to the city sewer line.
In rural areas where houses are not close together, a leaching cesspool or septic tank is used to dispose of all waste from the house. A cesspool is nothing more than a large hole in the ground lined with stone or concrete blocks placed in such fashion that the water can pass through the walls into the surrounding soil.
The disadvantage of this system is obvious. The soil around the cesspool will become contaminated in time, and this may lead to the pollution of the water supply, should it be drawn from a nearby well. Even if the well is located a considerable distance from the cesspool, there is no assurance that the water will not become contaminated.
It is quite possible, due to rock formations, for the sewage to reach the water supply even though the cesspool is lower than the well. When a well and a cesspool are in the same vicinity, it is wise to have the water in the well tested occasionally to be certain that it is pure.
Another disadvantage of the cesspool is that unless the top is tight and secure, insects and vermin will get into the sewage and possibly spread diseases.
The top of a cesspool should be of concrete, with a small opening left in the centre for inspecting the cesspool and pumping it out. This opening should be covered with a heavy block of concrete not easily moved. Do not cover a cesspool with wood planks; they are not airtight and will soon rot.
After a while, a cesspool will fill up and cause sewage to collect in the sewer pipes, often resulting in a flooded basement. The chief cause for a cesspool's filling up, aside from abnormally heavy use, is grease. Grease from the kitchen sink will penetrate between the rocks and bricks that line the walls of the cesspool and make a watertight coating.
As grease floats on water, it will rise with the water level, sealing the walls of the cesspool as it rises, until the entire wall surface is coated and the water cannot flow out into the soil.
The cesspool may be pumped out, but the walls will remain sealed and the cesspool will soon be full again. The only alternative, under these conditions, is to dig a new cesspool alongside the old one and connect the two with a few sections of soil pipe. The overflow from the first cesspool will pass into the second.
A grease trap will prevent most of the grease from entering the cesspool. This trap is installed between the kitchen sink drain and the cesspool. The water and grease from the sink drain flow into the trap and remain there long enough for the grease to rise to the top. The water underneath then flows out of the trap to the cesspool, leaving the grease in the trap. The trap should have a removable top, so collected grease can be removed.
The septic tank is a means of disposing of sewage in rural areas. It is a watertight, airtight container which holds the waste matter until natural bacteria in it, act on it and change most of the solids to liquid which then flows out of the tank into a disposal field. Some solids are never reduced to liquid but remain in the tank, and it must be cleaned out every few years. Hire a reliable firm to do that job.
The size of the septic tank will depend on the amount of waste from the home. A tank which is too large for amount of waste delivered will not operate properly. If the tank is too small for the volume of waste, the bacteria will not have sufficient time to work on the solid matter and the tank will fail to perform its function.
As a septic tank is a complicated piece of equipment, a specialist should be consulted if it becomes inoperative. It is necessary to have a complete understanding of the system before making any repairs.
The use of chemical drain cleaners should be restricted as much as possible in homes with septic tank, because some of these chemicals will kill off the bacteria in the tank and thus put it out of operation.