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

The purpose of a drain field in a septic system is to disperse effluent for natural filtration and treatment. When wastewater from the septic tank is released into the drain field, it is distributed through a network of perforated pipes buried in gravel-filled trenches. This allows the effluent to infiltrate the soil, where natural processes occur to filter out harmful pathogens and organic material.

The soil acts as a biological filter, with bacteria and other microorganisms breaking down contaminants, thereby treating the wastewater before it eventually reaches groundwater. This process is essential for preventing pollution and ensuring that the wastewater is adequately treated before it enters the environment.

In contrast, the other choices do not accurately reflect the function of a drain field. Collecting rainwater for irrigation does not align with the role of a septic system, which is designed specifically for wastewater management. Increasing water pressure in the septic tank is not a function of the drain field, as septic systems do not operate based on pressure but rather gravity and natural percolation. Finally, a drain field is not intended to provide a holding area for solid waste; that task is fulfilled by the septic tank, which temporarily holds solids and separates them from the liquid effluent.