On-Site Sewage Facilities (OSSF) are wastewater systems designed to treat and dispose of effluent on the same property that produces the wastewater.  A septic tank and drain field combination is the oldest and most common type of OSSF, although newer aerobic treatment units exist which represent scaled down versions of municipal sewage treatment plants.  OSSFs account for approximately 25 percent of all domestic wastewater treatment in the United States.                            

In order to assure that wastewater is disposed safely, a permitting and inspection program requires that all OSSFs must be in substantial compliance with state regulations.  

An OSSF permit is required for all new construction and anytime renovations significantly change the structure’s square footage or assigned water flow.  Permits are also required if the type or strength of the wastewater changes from a residential wastewater classification.  A repair/remodel permit is required anytime changes are made to an existing system.  The regulations require that an owner must obtain a permit to repair, extend, modify or alter any of the disposal system’s existing components.