The Perc Test
A percolation test, or “perc” test, consists of digging one or more holes in the soil of the proposed drain field. Presoak the holes, then runn 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.
A minimum of three test holes six to eight inches in diameter are drilled for leach line. These should be drilled to different depths from three to six feet below the surface. For better results, five drill holes are used in a pattern of one hole at each corner of the proposed drain field and one test hole in the center. Testing of these holes will result in a value with units of minutes per inch. This percolation value is then used to establish the size of the proposed drain field.