Percolation Test

If you're planning to install a new septic system, local ordinances will require you to conduct a soil percolation test. 

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A percolation test, or perc test is a test to determine the water absorption rate of soil in preparation for the building of a septic drain field (leach field). The results of a percolation test are required to properly design a septic system.

 

Percolation testing is observing how quickly a known volume of water dissipates into the subsoil of a drilled hole. 

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Sandy soil will absorb more water than soil with a high concentration of clay or where the water table is close to the surface.

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A percolation test consists of excavating one or more holes in the soil of the proposed leach field to a specified depth, presoaking the holes by maintaining a high water level in the holes, then running the test by filling the holes to a specific level and timing the drop of the water level as the water percolates into the surrounding soil.