Which type of soil requires the most lateral field for septic systems?

Soils classified as Group 4 typically have the lowest percolation rates and the highest clay content, which significantly impedes water movement through the soil. This poor drainage capability necessitates the use of a larger lateral field for septic systems to adequately disperse and treat effluent. By design, these systems rely on a greater area to provide sufficient absorption capacity, allowing the effluent to break down and be treated effectively within the soil.

In contrast, soils in Groups 1 through 3 generally exhibit better percolation rates and drainage properties, allowing for smaller lateral fields. Therefore, the requirement for a larger field in Group 4 reflects its distinct characteristics and challenges associated with effluent absorption and septic system functionality.