Failing a percolation test (or pert test for short) means that the land is not able to accept enough liquid through the soil to support a septic field. Holes are drilled and water is added to see how much the ground will absorb in that area.
A perk test is a percolation test conducted on soil to determine its absorption rate for the purpose of properly designing a leaching field to handle the sewerage generated by a building or buildings constructed on the property. Failure of a perk test would indicate that the soil is unsuitable for an appropriate system for the proposed or existing use.
