General Septic Information

A typical septic system has three main components:

• A septic tank;

• An absorption field; and

• The soil.

Microbes in the soil digest or remove most contaminants from wastewater before it eventually reaches groundwater.

Septic Tank

• The septic tank is a buried, watertight container typically made of concrete, fiberglass, or polyethylene.

• It holds the wastewater long enough to allow solids to settle out (forming sludge) and oil and grease to float to the surface (as scum).

• It also allows partial decomposition of the solid materials.

• Compartments and a T-shaped outlet in the septic tank prevent the sludge and scum from leaving the tank and traveling into the absorption field area.

• Newer tanks generally have risers with lids at the ground surface to allow easy location, inspection, and pumping of the tank.

Absorption field

• The wastewater exits the septic tank and is discharged into the absorption field for further treatment by a biomat and the soil.

• The partially treated wastewater is pushed along into the absorption field for further treatment every time new wastewater enters the tank.

• A reserve absorption field, required by many states, is an area on your property suitable for a new absorption field system if your current absorption field fails.

• Treat this area with the same care as your septic system.

Soil

• Septic tank wastewater flows to the absorption field, where it percolates into the soil, which provides final treatment by removing harmful bacteria, viruses, and nutrients.

• Suitable soil is necessary for successful wastewater treatment.

• The purified wastewater eventually evaporates from the soil, is taken up by plants or percolates into the groundwater.

Types of Conventional Septic Systems 

• Shallow Trench System – the trench is dug one foot or less (no deeper than one foot into the soil). Draining is either through a perforated pipe and drain rock or a chambered system.

• Standard Trench System – the trench is dug down four feet or less. 

• Deep Trench System – the trench is dug down four to seven feet. The draining system consists of drain rock with the perforated pipeline on top of the rock.

• Chamber System- This type of system consists of a series of connected chambers. The area around and above the chambers is filled with soil.

Types of Alternative Septic Systems 

• Mound- constructed sand mound that contains a drain field trench. 

• Pack Bed Media- device that uses materials designed to treat effluent by reducing BOD and/or removing suspended solids in an unsaturated environment; biological treatment is facilitated via microbial growth on the surface of the media.

• Membrane Bioreactor-  a process which combines a microfiltration or ultrafiltration membrane unit with a suspended growth bioreactor.