The septic tank is a simple and effective means of sewage disposal for houses which have running water but are without access to public sewer systems. When properly installed, it provides a satisfactory and relatively inexpensive method of preparing sewage for final disposal. Bacterial action within the septic tank disintegrates the sewage so that it can be absorbed into the ground.
The essential parts of a septic tank system are the house sewer, the septic tank, the outlet sewer line, the distribution box, and the disposal field. The house sewer is the pipe line that carries household wastes from house to septic tank; the septic tank is the watertight container wherein sewage is disintegrated by bacterial action; and the outlet sewer line, which is made of tile, carries liquid wastes from the septic tank to a distribution box that discharges liquid wastes into the disposal field through drain-tile lines and permits them to seep into the soil.
The location of the septic tank as well as the disposal lines should be plotted for purposes of cleaning and repair, and a record of inspections and cleanings should be kept.
Clogging of the disposal field is the most common trouble and may be caused by the tank being too small for the volume of sewage, by failure to clean the tank regularly, by improper arrangement of the interior so that slow flow through the tank is not provided and scum or sludge is allowed to pass out with the effluent, or by a disposal field which has been incorrectly located or is too small.
The frequency of cleaning will depend upon the size of the septic tank and the volume of sewage flowing into it. When the space between the scum and the sludge becomes one-half of the total depth of the tank, cleaning is advisable.
If a disposal field is clogged, it may be necessary to dig up and clean the tiles and re-lay them 3 or 4 feet to one side or the other of their original position. Sometimes it is possible to clean a tile line by opening the line at each end and flushing it thoroughly with a hose. In this case, provision should be made for disposal of the water used.
If flushing is not successful, it may be necessary to use a flat steel sewer rod to remove roots or solid obstructions.
Tile lines which are laid with an improper slope will permit the effluent to collect and saturate the soil, and cause unpleasant odors. As bacteria cannot work in such areas, the lines must be relaid on the correct slope. A disposal field that is too small may also cause odors or a water-logged soil.
The house sewer and the outlet sewer line become clogged more often by roots than by waste material which has been discharged with the sewage. Grease may also cause trouble, particularly if the slope of the pipes is inadequate. While drain solvents are effective in clearing the pipes of waste material, it may sometimes be necessary to use a flat steel sewer rod to dislodge a more solid obstruction. If these methods are not successful, the lines may need to be uncovered for the purpose of rodding from two directions. If stoppage is caused by an excessive growth of roots, the lines may need to be relaid with root-tight joints or moved to new locations.