Prior to the institution of soil testing, a percolation or "perc" test was performed. This procedure involved digging a hole in the ground, filling it with water, and timing how long it took to drain or percolate the water into the surrounding soil. As time passed, more and more systems were failing prematurely. It turned out that many "perc" tests were performed on poor soils and were done in late summer and early autumn when ground water was low. This would ensure the property would pass for a conventional system. Well as you may be aware, water levels in the soils of Wisconsin vary greatly during the year. In spring, due to snow and frost thawing, levels are at a yearly high in many areas. These levels recede until winter frost sets in and the cycle starts again. Soils that are dry and capable of absorbing effluent from a septic tank during late summer and early fall may be completely saturated early each year and not suitable for treating wastewater in spring and early summer. This "perc" test also failed to consider a number of other important and neccessary factors in determing whether soils present were capable of treating wastewater effectively year round.

In response to the shortcomings of the "perc" test, the current soil testing regulations were developed. Limiting factors such as high seasonal groundwater (less than three feet from surface ANY TIME DURING THE YEAR), high bedrock, soil being disturbed (land fills, compact soils, etc.) are now considered as part of the evaluation. Other factors must also be weighed. These include the clay, silt and sand content of the soils, soil structure, soil profile, mottling (discoloration due to seasonal changes in ground water levels), etc. are also factored into the evaluation. All of these factors determine what type of POWTS is to be installed. Some parcels of property will not allow for any POWTS to be built and you may have to install a holding tank or not be allowed to build at all. Many local communities will not allow a holding tank to be installed for new construction.

Please note that if you have an existing system that needs to be replaced, the state of Wisconsin will waive some or all of these rules to allow a replacement system to be installed. These experimental systems include aerobic treatment plants, sand filters, and modified mound systems, or a holding tank. These systems may be included as a standard POWTS in new regulations now under consideration. Currently a waiver from the State may be required. Talk to your local soil tester or installer. The state cannot condemn your property because of poor soils. Also, if you are forced to build your home with a holding tank, once you occupy the house you may be able to obtain a waiver to build a POWTS.

Specific dimensions and cited requirements refer to Wisconsin Administrative Code ILHR83. This is not to imply that this website has been reviewed, approved, or recognized by any regulatory agency.