A conventional septic system is a type of OSSF that consists of a septic tank and a soil treatment area or drain field. This is the most common type of OSSF or septic system in the world.

Wastewater that is generated inside of the home or business is introduced to a tank, typically constructed with two compartments. Inside the first compartment, solids are separated from the wastewater column through separation. Heavy solids will settle to the bottom and create a sludge layer while oils, greases and lighter solids will float to the surface and create a scum layer. There are anaerobic bacteria in the tank that very slowly and ineffectively break down the solid material in the wastewater column. This process of separation and bacterial action creates a clear zone in the middle of the water column. Water is then transferred to the second compartment of the tank, where it allows for secondary separation.

From this point the effluent is introduced to the soil treatment area, commonly referred to as the drain field, distribution field, or lateral lines. The distribution component is most commonly constructed of perforated pipe and gravel, however there are other methods with which to construct the distribution component such as leaching chambers, gravelless pipe and others.

The majority of treatment in a conventional septic system occurs in the soil treatment area, through the percolation of the effluent through the soil where natural processes occur by filtering out harmful bacteria, viruses and nutrients. Therefore, it is important to maintain the conditions of the tank through regular and routine pumping in order to prolong the life of the soil treatment area.

Conventional septic systems are passive in nature and rely on gravity and the natural conditions of the soil to treat and dispose of the effluent.

There is a common misconception that septic tanks do not need to be pumped out. This is not true!! Regular maintenance and routine pumping are critical to minimize failure of the septic system. It is recommended these septic systems be pumped every 2-5 years.