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

The purpose of a drain field, also known as a leach field or absorption field, in a septic system is to allow treated effluent to disperse into the surrounding soil. After waste is processed in the septic tank and solids settle, the liquid, or effluent, is directed to the drain field. Here, this effluent undergoes further treatment as it passes through the soil, which acts as a natural filter.

The soil microbiota play a critical role in breaking down any remaining harmful pathogens, nutrients, and organic material from the effluent. The proper design and functioning of a drain field are vital for maintaining the efficiency of a septic system and ensuring that groundwater and nearby water sources are protected from contamination. This dispersal process helps mitigate environmental impact while efficiently managing waste.