How Do Septic Systems Work?

How Do Septic Systems Work?

How Do Septic 
Systems Work?

What a Septic System Is

A septic tank system uses natural processes to treat and dispose of the wastewater generated in your home. It typically consists of a septic tank and a drainfield, or soil absorption field. This septic tank provides the first step in treatment. As wastewater flows into the tank, the heavier solids settle to the bottom to form a sludge layer, and the lighter solids, greases, and oils float to the top to form a scum layer. In a typical drainfield, the liquid wastewater (effluent) from the tank flows into the drainfield that is made up of perforated pipes, to be distributed and then treated by the natural soil system.

How Your Septic System Operates

The septic tank provides some biological treatment of the sludge and scum layers that accumulate there. The majority of treatment occurs in the drainfield where the effluent enters the soil and is treated as it percolates to the groundwater. The soil acts as a biological and physical filter to remove harmful substances, including disease-causing bacteria and viruses, toxic organics and other undesirable wastewater constituents. 
Outlet filters or baffles are located in the tank and are designed to prevent the sludge and scum from flowing into the drainfield. If the tank is not pumped regularly to remove the accumulated solids, the tank will fill with sludge and the solids will be washed out into the drainfield, or clog the outlet filter. If solids reach the drainfield or clog the outlet filter, they will quickly clog the soil and eventually lead to system failure.
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