The septic tank holds the wastewater in the tank long enough for solids and liquids to separate. The wastewater forms three layers inside the tank.
Sediments lighter than water (such as greases and oils) float to the top forming a layer of scum. Sediments heavier than water settle at the bottom of the tank forming a layer of sludge. This leaves a middle layer of partially clarified wastewater.
The layers of sludge and scum remain in the septic tank where bacteria found naturally in the wastewater work to break the solids down. The sludge and scum that cannot be broken down are retained in the tank until the tank is pumped.
Septic tank pumping removes the build-up of sediments that can damage the system leading to early failure of the absorption field.
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