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

The primary purpose of a drain field, also known as a leach field or soil absorption field, is to treat wastewater before it reaches groundwater. In a septic system, wastewater from the home flows into a septic tank where solids settle to the bottom, and the liquid effluent is then directed to the drain field.

In the drain field, the effluent percolates through the soil where microbial action breaks down the organic matter and pathogens, effectively treating the wastewater. The soil acts as a natural filter, removing contaminants and allowing the treated water to be safely absorbed into the groundwater. This process is crucial for protecting public health and the environment by ensuring that harmful substances are adequately filtered before they enter the water supply.

The other choices do not accurately reflect the primary function of a drain field. While the drain field does manage the flow of wastewater, its main role is not to store wastewater, aerate sewage, or serve as a backup system but to facilitate the natural treatment process.