What is the primary function of a drain field?

The primary function of a drain field, also known as a leach field, is to distribute effluent for further treatment. After wastewater exits the septic tank, it contains both liquid and solid components. The septic tank's role is to settle solids, allowing the liquid effluent to flow into the drain field.

Once in the drain field, the effluent is spread out into the soil, where it undergoes further treatment through natural processes. Beneficial microorganisms present in the soil break down remaining organic matter, while the soil acts as a filter for physical and biological contaminants. This step is crucial in ensuring that the treated effluent is adequately purified before it eventually returns to the groundwater system.

The other options do not accurately reflect the primary purpose of a drain field. The collection of solids occurs within the septic tank, not the drain field. The stored untreated wastewater is also contained within the septic tank until treatment occurs. The filtration process involving filtering water before it enters the septic tank is not a function of the drain field, as the septic tank is the first point of treatment for incoming wastewater.