One of the most neglected components of a home is the septic system. Most people don't realize that septic systems are not self maintaining and need serviced. A system should be pumped every three to five years depending on your family size. Since 2000 septic systems have a filter that needs to be cleaned every three years, and in my opinion should be cleaned once a year to prevent blockage.
The most common septic system is a gravity flow system. It consist of waste tank, distribute box and effluent drain lines. Depending on the soil, number of bedrooms and topography that will determine the tank size and the number of drain lines and length. Second most common type of system is the above plus a holding tank with a pump. This is usually for pumping the fluids from the holding tank to the distribute box located higher up the grade or to a different location off the property.
The waste tank consist of two compartments divided by a baffle wall. The baffle wall is located across the width of the tank and it extends from the top down and bottom up leaving a slot in the center. This keeps the solids that sink to the bottom and the grease that floats on the top from passing over to the second compartment. The first compartment will hold the solids and fats and oils while it breaks down. Typically the fats oil and grease will stay afloat on the top of the tank and the solids will sink to the bottom. The solids will break down to a certain extent but the grease will not. The effluent in the center of the two will pass through the baffle wall and over into the second chamber compartment for further microbe break down. In the second department there is an outlet pipe with a baffle "T" which also helps keep Solids from leaving the tank and possibly obstructing the drain field lines.
In 2000 they required filters to be installed in the "T" to further help with drain field obstruction. This filter will need pulled out and cleaned periodically to prevent it from being stopped up and backing up your system. In the first compartment of the waste tank the solids will only break down to a certain point. The fats and oils will accumulate on the top and the tank buildup on the top and bottom will give less Retention time for the new waste to break down. Over time the less retention time can cause blockage and possibly field failure.
The two systems mentioned are the most common type and there are numerous types of systems that need maintained on a more frequent basis. Get educated about the type of system you have and you should have many years of trouble free use.
To read more about septic systems and the Dos and Don'ts visit my web site at http://www.houseinspections.com/ and click on the septic link. I am a certified septic inspector issued by the state and would be glad to answer your questions or schedule an appointment.