What is the function of a drainfield in a septic system?

The function of a drainfield in a septic system is to absorb and disperse liquids into the soil. When wastewater from the septic tank flows into the drainfield, it is distributed through a network of perforated pipes buried in gravel or another type of permeable material. This setup allows the liquid effluent to seep into the surrounding soil. As the liquid moves through the soil layers, beneficial microorganisms break down remaining contaminants, effectively purifying the water before it reaches the groundwater. This is a crucial step in the wastewater treatment process, as it helps maintain environmental safety and protect public health.

In contrast, a drainfield is not designed to store liquid waste; that function is a role of the septic tank where initial separation occurs. It also does not filter solids from sewage, as that is primarily the job of the septic tank, which allows heavier solids to settle at the bottom. Additionally, while some systems may have backup features, the main responsibility of the drainfield is not to provide storage but to facilitate the safe absorption and treatment of effluent.