Therefore, prospective home buyers should ask their local health department whether the septic tank is properly designed and large enough to serve the anticipated number of occupants of the home.

They should also ask if the tank is located where it is likely to endanger the water supply, and whether the leaching system, pits or tile fields are capable of disposing of liquid wastes at all times and under year-around weather conditions.

The purpose of a septic tank is to receive household wastes (soapy water from the laundry and the bath, discarded food scraps, body wastes, etc.).  The solids settle to the bottom of the tank and the liquid passes into the leaching system, where it seeps out and is absorbed into the soil. Bacteria in the soil then remove some of the impurities from the liquid wastes.

When septic tank systems are improperly designed or maintained, overflows of liquid wastes to the ground surface will often occur. Not only do these overflows create offensive odors, they are also a health menace. They may contain the germs of typhoid fever and dysentery. They are excellent breeding places for certain species of mosquito and other disease-carrying insects. They are particularly a threat, therefore, to children and pets playing on the property.

The frequency with which it must be cleaned, however, depends on the size of the tank, the daily flow of sewage into it from the home, and the number of people it serves. Where a household garbage grinder is used, more frequent cleaning will be required unless the tank is large enough to accommodate the additional wastes. With ordinary use and care, the tank may need cleaning every 2 years. The home owner can ascertain for himself those periods when the tank needs cleaning.  When the total depth of scum and solids exceeds 1/3 the liquid depth of the tank, the solids should be removed.

There are no chemicals or digesting yeasts which are capable of reducing the solids in a septic tank to the point where cleaning is unnecessary. They can be removed properly only by persons having some knowledge of the operation. In nearly every community in which septic tanks are employed, there usually is a company whose business it is to clean septic tanks. The local health department probably can help in obtaining this service.

Solids should be removed from the tank in the spring of the year because warm weather hastens the bacterial action within the tank which digests the fresh, incoming sewage. Because they give off obnoxious odors and may contain dangerous disease bacteria, the removed solids disposed of in a manner approved by the local health department.

To facilitate cleaning and maintenance operations, the home owner should provide himself with a diagram of the septic tank system. It should show the location of the house, the septic tank and manholes, the piping, and the leaching system.  The lower hall of the same page contains space in which a tank cleaning record may be kept. This information should remain on the premises, regardless of a change in occupancy.

Septic tanks and leaching systems frequently are damaged by heavy trucks or equipment moving over the area under which they are located. A diagram of the system, therefore, will enable the home owner to guide vehicles away from the critical area.  If there is no way to avoid crossing the sewer line, then a line of cast iron pipe instead of tile should be installed under the crossing.
 
The roots of trees and shrubbery are a common source of trouble. They may enter the tile lines and clog them so completely at times that the liquid wastes are forced to the ground surface. When this occurs, the roots can be removed only by digging up and cleaning the tile lines. Leaching systems suffer the most frequently, however, from neglect of the septic tank. When the tank is neglected, solids fill it up and flow into the leaching system, where they stop the flow of liquid wastes.  The system then must be uncovered, cleaned, and relocated. This is a costly undertaking and emphasizes the need for periodic inspection and cleaning of the septic tank.  These precautions will save needless expense and trouble.