How A Septic System Works

There are many different styles and sizes of septic systems, but they all essentially perform the same function: process wastewater into a cleaner effluent that’s distributed underground, and safely blended with groundwater. Septic systems are broken up into passive and active systems, with the majority of residential homes having passive systems.

The moment you flush a toilet, the wastewater flows from the house, through the inlet pipe (of a passive system), and into the septic tank. An equal amount of effluent is displaced in the tank and flows out of the tank to the drain field. It eventually disperses into the ground.

Your tank is home to an enormous population of microorganisms, known as anaerobic bacteria. The amount of bacteria in your tank relies specifically on the solid organic material in the wastewater (as these microorganisms use this waste as a food source).

Tanks are designed to always maintain a minimum water level. The proper level of the septic tank is just below the inlet and outlet PVC tee in the tank. When at this level, the septic tank is considered to be at “normal operating level”. Tanks must be full to work properly.

Why maximizing the time that bacteria can breakdown organic material is critical:
Anaerobic bacteria are slow-acting bacteria. As such, it’s vital that your tank allows for the most possible time for breakdown to occur. This occurrence is known as the “holding time” and is defined by how long it takes for wastewater to flow from the inlet of the tank to the outlet.

An average septic tank holds wastewater for around two days. This holding time allows the bacteria to break down the waste by an average of 40 percent. The bacteria can continue to complete the treatment of the effluence once it reaches the drain field.