What typically happens to heavier solids in a septic tank?

In a septic tank, heavier solids, which primarily consist of materials like food particles, grease, and human waste, typically sink to the bottom due to their density. This process of settling is crucial for the proper function of the septic system. As these solids accumulate, they form what is known as sludge at the bottom of the tank.

This mechanism is essential for effective wastewater treatment. Meanwhile, lighter materials, such as fats and oils, tend to rise and form a scum layer on the surface of the tank. Gases produced during the anaerobic digestion of organic matter occur throughout the tank but do not influence the settling of heavy solids significantly. Proper management of these solids is vital; if left unaddressed, the sludge can build up and may require pumping to maintain the tank’s efficiency.

In contrast, solids floating to the surface or transitioning into gas would disrupt the tank's balance, leading to potential clogs and system failures. Discharging solids out of the tank is not viable since the function of a septic tank is to treat waste, not expel solid materials directly. Thus, the action of heavier solids sinking to the bottom is a fundamental aspect of septic tank operation.