Percolations Tests

If you’re considering purchasing rural land not connected to the municipal sewer system, you need to make yourself familiar with the percolation (perc, perk) test. Traditional septic systems only work when the proposed drainfield area is permeable enough to absorb the effluent flowing into it from the septic tank. Also, there must be at least a few feet of good soil from the bottom of the trenches to rock or impervious hardpan below, or to the water table. To determine if a building site is suitable for a septic system, a percolation test (typically called a “perc test’ or “perk test”) is required.

Percolation tests are also needed to install new drainfields on properties where the existing one has failed. Every property has different needs and systems are sized based on the percolation rate and soil type. A failed perc test means that a new system cannot be installed. For new home lots, you should make any offer to purchase land contingent on the site passing the soil and perc tests.

Chavis Septic Services handles the permitting process and testing process for you. The perc test process consists of digging several 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. We follow all MDE and local specifications when conducting percolation tests.


What Does a Percolation Test Consist Of?

It starts with contacting the local health department and setting up a time to meet onsite where the perc test will be conducted.

A backhoe must be present onsite with an experienced operator. A trench must be dug according to the health specialist’s specifications and the soil horizons, layers, and soil type will be evaluated.

A smaller hole is then dug and water is placed inside. The water level will drop at a certain rate, which is recorded and used to calculate the absorption rate of the soil present on the property. This absorption rate is used to calculate the sizing requirements of the new septic system and absorption area to be installed.


Call us today at 410-838-1200 to schedule a soil percolation test.

a perc test determines septic system readiness
Drainfield Trench Percolation Test