basic testing method is essentially the same. A hole, typically three to four feet in diameter is drilled to a depth of twenty or thirty feet (depending on the local groundwater table), and a fire hose is used to fill the pit as quickly as possible, and then, again, its dissipation rate is observed. This rate is used to calculate the size and number of pits necessary for a viable septic system. Finally, for leach line systems and horizontal seepage pits, a "deep hole" is drilled to find the water table or to approximately twelve feet (dry). Exact depths will again depend on local health codes. In the case of a vertical seepage pit, local groundwater data may be used, or if the drill hole reaches groundwater, the pit will be backfilled again according to county health code. Alternatives Some jurisdictions question the accuracy of a percolation test to assess the treatment quality of soil and instead utilize soil texture analysis--along with long-term acceptance rates (LTAR)--in place of, or in addition to, a percolation test. References How to Run a Percolation Test Sewerage Soil physics