How does soil assist in treating wastewater in a septic system?

In a septic system, soil plays a crucial role in treating wastewater by breaking down contaminants and purifying the water. This natural biological process is facilitated by microorganisms present in the soil, which decompose organic matter and harmful pathogens. As wastewater flows through the soil layers, these microorganisms metabolize nutrients and toxins, effectively reducing harmful substances and improving water quality.

The soil acts as a living filter, where the physical and chemical properties contribute to contaminant removal. As wastewater percolates through the soil, larger contaminants are physically trapped, and the microbial activity helps to continue breaking down smaller organic materials. The result is cleaner, treated water that can safely re-enter the groundwater system.

Other choices address aspects of the filtration process or introduce inaccuracies, such as chemical agents being added, which is not a function of soil in this context. The primary action of soil in a septic system centers on ecological processes rather than external chemical interventions, highlighting its critical role in the natural treatment of wastewater.