What is placed below the distribution pipes?

What is placed below the distribution pipes?

• A. Gravel
• B. Sand
• C. Septic stone
• D. Clay

Answer: (C)

In a septic drain field, the distribution pipes sit on a bed of coarse, clean aggregate that provides a stable, well-draining foundation for the pipes and allows effluent to flow into the surrounding soil. This material, often called septic stone, creates the necessary void space for drainage, resists compaction, and keeps fine soils from entering the pipe. Sand is too fine and would clog the system; clay is nearly impermeable and would block drainage; gravel can serve a similar purpose but septic stone is the specific aggregate typically specified for this layer in many installations, so it’s the best choice here.

In a septic drain field, the distribution pipes sit on a bed of coarse, clean aggregate that provides a stable, well-draining foundation for the pipes and allows effluent to flow into the surrounding soil. This material, often called septic stone, creates the necessary void space for drainage, resists compaction, and keeps fine soils from entering the pipe.

Sand is too fine and would clog the system; clay is nearly impermeable and would block drainage; gravel can serve a similar purpose but septic stone is the specific aggregate typically specified for this layer in many installations, so it’s the best choice here.