What is the purpose of a septic drain field?

The purpose of a septic drain field is to allow treated wastewater to percolate into the soil. In a septic system, wastewater first goes into the septic tank, where solids settle to the bottom and are broken down by bacteria. The liquid effluent that emerges from the tank is already partially treated but still contains pathogens and nutrients. The drain field, also known as a leach field, is designed to further treat this effluent as it moves through the soil.

As the treated wastewater percolates through the gravel and soil layers in the drain field, it undergoes additional natural filtration processes. The soil acts as a biological filter, removing harmful bacteria, viruses, and nutrients, which helps to protect groundwater and the surrounding environment. The drain field is crucial for ensuring that the effluent is adequately treated before it reenters the groundwater system.