How deep should percolation test holes typically be?

Percolation test holes are crucial for determining the suitability of soil for septic systems. The typical depth for these holes is aimed at reaching a level where the soil texture can be accurately assessed for its absorption capability, which is essential for the design of an effective drain field.

The most common depth for percolation test holes, 6-8 inches, facilitates a proper analysis of the soil's permeability and structure. This range allows for a sufficient volume of water to saturate the soil and observe the rate of absorption, which informs decisions regarding system sizing and design.

Deeper test holes may not necessarily provide better results, as they can reach layers of soil that might behave differently than the upper soil layers critical to the absorption process. Moreover, shallower holes can lead to test results that may overlook critical soil features that influence drainage. Thus, the depth of 6-8 inches strikes a balance between being deep enough to assess soil conditions while remaining practical for a septic system evaluation.