We have lived here four years and have not had our septic tank emptied.
My aunt in KY has lived in her house since 1974 and has not had to have it emptied. It has never backed up or given her any problems.
Has someone who does not stand to profit given you a reason why yours needs to be emptied annually?
Your Aunt does not have a septic system but a cesspool.
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Will I Need to Pump the Tank?
After a few years, the solids that accumulate in the septic tank should be pumped out and disposed of at an approved location. If not removed, these solids will eventually overflow, accumulate in the drainfield, and clog the pores (openings) in the soil.
This blockage severely damages the drainfield. While some clogging of soil pores slowly occurs even in a properly functioning system, excess solids from a poorly maintained tank can completely close all soil pores so that no wastewater can flow into the soil. The sewage effluent will then either back up into the house or flow across the ground surface over the drainfield. If this happens, you may need to construct a new drainfield on a different part of your lot. Pumping the septic tank after the soil drainfield has become completely clogged will not rejuvenate the system. It will provide only a few days reprieve until the tank fills up again.
How Will I Know When to Pump the Tank?
The frequency with which you will need to pump depends on three variables: the size of your tank, the volume of your wastewater, and the solids content of your wastewater. If you are unsure about when to have the tank pumped, observe the yearly rate of solids accumulation. The tank should be pumped if the sludge layer has built up to within 25 to 33 percent of the liquid capacity of the tank. Therefore, a typical 1,000 gallon tank with a 4-foot liquid capacity should be pumped when the solids are 1-foot thick in the bottom of the tank. If the tank is not easily accessible, you may wish to inspect and pump it according to the frequency guidelines in Table 1. Your local health department should be able to tell you the size of your tank. When inspecting the tank, check the sanitary tee or the outlet baffle to be sure that it has not broken off and dropped into the tank. Also, be sure to have both compartments of the tank pumped.
Table 1. Estimated Septic Tank Inspection and Pumping Frequency in Years
Tank Size
(gallons) Number of People Using the System
1 2 4 6 8
900 11 5 2 1 <1
1,000 12 6 3 2 1
1,250 16 8 3 2 1
1,500 19 9 4 3 2
Source: Adapted from "Estimated Septic Tank Pumping Frequency," by Karen Mancl, 1984. Journal of Environmental Engineering. Volume 110.
If the septic system is not used very often (as in an infrequently used vacation home with a correctly sized tank), it will probably not need to be pumped as frequently as indicated in the table. If you use a garbage disposal, the tank may need to be pumped more frequently. After a few inspections, you should be able to adjust the schedule according to the rate at which solids accumulate.
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http://www.soil.ncsu.edu/publications/Soilfacts/AG-439-13/