Private Onsite Wastewater Treatment System

The sanitary regulations apply to any development that is not connected to a municipal sewer system. Development in this case applies to residential uses and to commercial or industrial uses that have employees. The authority to regulate Private Onsite Wastewater Treatment Systems (POWTS) comes from Wisconsin Administrative Code.

The Administrative Code Sections that apply to POWTS include chs. Comm 5, Comm16, Comm 82-87, and Comm 91. Some of the code sections apply only partially to POWTS and others apply entirely to POWTS. Chapter 9 of the County Ordinance is simply the county procedure to administer these code sections. Component manuals for Comm 83, effective July 1, 2000, can be obtained from the Wisconsin Department of Safety and Professional Services, including an on-line Sanitary Permit Application form SBD-6398 (R. 11/11) that must be submitted to the County for every new POWTS.

POWTS Function & Procedure

POWTS come in many varieties but they have some common elements or procedures. Generally water runs down gradient from the residence into a septic tank and it is then dispersed into the treatment / disposal area.

The septic tank is designed and sized to allow the wastewater to have some retention time in the tank. This is to allow the heavier material to fall to the bottom as sludge and the lighter oils and greases to float to the top as scum.

Bacteria inside the septic tank digest some of the solids converting them to gases and water. This process reduces the volume of solid material stored within the tank. This should mean that only the partially treated or clarified liquid (effluent) is discharged to the treatment / disposal area.

It is important to clean the tank periodically to allow enough volume for retention of waste and the settling of solids. If the sewage does not have adequate retention time within the tank, some solids, oils, and greases will be discharged to the treatment / disposal area. This will lead to premature plugging of the soil pores and ultimately to the failure of the treatment / disposal area. This can create a very serious public health risk as well as being expensive to correct.

As of July 2000, Wisconsin Administrative Code requires effluent filters to be installed in new and replacement septic systems to prevent premature failure of the treatment / disposal component of the system.

Limits & Failures

All the wastewater created must discharge into the POWTS. Everyone must recognize that the soils ability to accept wastewater from the laundry, kitchen, and bathrooms is not limitless.

There is a limit to how much and how rapidly the soil can accept wastewater. If this rate or volume is exceeded, the POWTS will develop problems, potentially leading to failure.

Many older systems were installed prior to the existence of plumbing codes, thereby allowing them to be poorly constructed or installed in poor locations or in unsuitable soils. When systems fail there is often a combination of factors involved. They may be poorly located, improperly constructed, or received abuse and neglect over time by their users.