What type of septic system is best for locations where the water table is 6 inches below grade during the wet season?

A mound septic system is particularly suitable for locations where the water table is only 6 inches below grade during the wet season. This type of system is designed to elevate the septic drain field above the natural ground level, allowing for proper drainage and treatment of wastewater even when the water table is high.

In situations where the water table is near the surface, conventional systems would not function effectively because they rely on gravity to distribute wastewater into the soil, which could lead to flooding and backup in the system. Sand filter systems, while they can improve drainage in certain conditions, may still struggle in high water table scenarios without additional elevation measures that a mound system inherently provides. Engineered systems might be viable, but they often require specific design considerations to address the challenges presented by high groundwater.

Therefore, a mound system is the best option in this context, as it is purposefully constructed to handle sites with high water tables by using a mound of soil to provide additional filtration and treatment distance for the wastewater before it reaches the natural groundwater.