Septic System Basics


What Makes Up a Septic System?

A typical septic system consists of 2 main parts:
The Septic Tank and The Drain Field or Seepage Pit

cross section diagram


Septic Tank

A buried water-tight tank that is usually between 1000 and 1500 gallons. It receives wastewater from the home which is partially treated by naturally occurring bacteria in the tank. Heavy solids settle to the bottom of the tank while greases and lighter solids float to the top. The solids stay in the tank while the wastewater is discharged to the drain field for further treatment. Solids are then pumped from the tank every 2 – 5 years by a licensed septic service company.

The Drain Field (& The Soil)

The job of the drain field is to accept and partially treat wastewater from the septic tank before it is returned to the water table. Once the wastewater reaches the soil, it is purified by naturally occurring bacteria which removes toxins, chemicals, and pathogens from it.


Types of Drain Fields

illustration graphic
Standard Drain Fields

This type of system relies on gravity to get the job done. Typically, there is a distribution box (D-box) connected to several drainpipes buried in gravel filled trenches. The drainpipe is perforated allowing the wastewater to exit into the gravel where it is treated by natural bacteria occurring in the drain field and surrounding soil.

Infiltrator® Systems

Infiltrator chambers are hollow structures installed in the trenches without any gravel. The bottom half of the hollow chambers are open to allow proper flow of wastewater in to drain field. They also have lateral sidewalls, which help with the absorption of the wastewater into the soil.

Mound Systems

As the name suggests, the mound system uses an above-ground mound built on top of the soil to help treat and disperse wastewater.

The wastewater is moved to the mound through a pump in front of the septic tank. The pump moves all wastewater to the above-ground mound.

Seepage Pit

A seepage pit is quite literally a pit in the soil that goes straight down to a maximum of 3 feet above the water table. The hole has perforated stones lining up the sides.

The pit is connected to the septic tank, and wastewater flows directly into it and is treated by the soil in which the hole is made.


The Bio-Mat

The bio-mat exists to treat wastewater before it reaches the local water table.

The bio-mat manages this through a two-step process to remove pathogens in the water. The first step is to pass the wastewater through anaerobic and aerobic bacteria in the septic tank and the drain field, respectively. The bacteria eat away at the waste and lets the water pass through to the soil.

The second step is for the treated water to pass through the soil, where it is filtered for any remaining pollutants.

The bio-mat develops on the sides and bottom of the trenches and is made up of solids from the wastewater, minerals, microorganisms, and sulfites.

bacteria pseudomonas image

The bio-mat is a necessary part of the septic tank system and in cleaning the wastewater before it travels to the soil. When flooded, the aerobic bacteria die, which throws off the balance of the system. In that case, use Mega Bio, a bioenzymic formula that can restore order to your bio-mat and keep it functioning.


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