What is the primary role of the drain field in a septic system?

The primary role of the drain field in a septic system is to allow treated wastewater to percolate into the soil. After wastewater is treated in the septic tank – where solids settle and are anaerobically broken down – the liquid effluent is released into the drain field. The drain field consists of trenches filled with gravel or crushed stone, which provide space for the effluent to seep out and enter the surrounding soil.

This soil acts as a natural filter, further treating the wastewater through microbial activity as it moves through the soil layers. This process is essential for ensuring that contaminants are removed before the filtered water ultimately enters the groundwater supply. The effectiveness of the drain field is crucial for protecting public health and the environment, as it helps to minimize the potential for contamination.

The other options pertain to different stages or components of the septic system, but they do not accurately describe the specific function of the drain field itself.