What is the function of a drain field in a septic system?

The drain field, also known as a leach field, plays a crucial role in the septic system by distributing and treating effluent through soil filtration. When wastewater flows from the septic tank, it is directed to the drain field where it is spread out through a network of perforated pipes laid in trenches filled with gravel or other materials.

This setup allows the effluent to percolate into the surrounding soil, which acts as a natural filter. As the wastewater seeps into the soil, various microorganisms present in the soil break down and treat the contaminants, effectively purifying the water before it eventually reaches the groundwater. This process is vital for preventing pollution and maintaining the integrity of the local water supply.

The other options do not accurately describe the function of a drain field. The drain field does not contain wastewater indefinitely; instead, it facilitates its treatment and absorption into the earth. It also does not discharge waste into nearby water bodies or heat wastewater before treatment, both of which are not functions relevant to its primary role in a septic system.