What happens to the solid waste in a septic tank over time?

Solid waste in a septic tank undergoes a natural process of decomposition over time. When wastewater enters the septic tank, solids settle at the bottom to form sludge, while lighter materials, such as grease and fats, float to the top to form scum. The solids that settle out experience decomposition by bacteria present in the tank. These bacteria break down the organic material, reducing the volume of sludge over time.

This process is crucial for the overall function of the septic system, as it allows for the effective treatment of wastewater before it is released into the drainage field. Without this settling and decomposition, tanks would fill up quickly, leading to system failures and potential environmental hazards. Regular pumping is necessary to remove the accumulated sludge and scum to ensure the system functions properly, but the main process occurring with the solids in the tank is the settling and bacterial decomposition that forms sludge.