What is the primary function of a disposal field in a subsurface sewage disposal system?

The primary function of a disposal field in a subsurface sewage disposal system is to absorb and treat septic tank effluent. This process is essential for the proper functioning of the septic system. After wastewater exits the septic tank, it is not yet clean enough to return to the environment. The disposal field, often composed of a series of trenches filled with gravel or other materials, receives this effluent and allows it to percolate through the soil.

As the effluent moves through the soil layers in the disposal field, it undergoes natural biological treatment. Microorganisms present in the soil break down organic matter, pathogens, and nutrients, effectively treating the wastewater before it reaches the groundwater. It is vital that this function is performed correctly, as it helps to maintain environmental and public health by preventing contamination and ensuring that the treated effluent is safe for reintroduction into the ecosystem.