Onsite Sewage Disposal

Onsite sewage disposal is a broad term used to describe a system that treats biological or chemical effluent in the place where it originated. In other words, it's your septic system, complete with a tank that sorts, stores and treats solids as well as a leach field that distributes the fluids over a sand and gravel bed. Your septic system is a critical part of your home. It should be treated with care to ensure its effectiveness in treating the effluent we produce in our homes.

For new construction of a home, business or other building from which sewage emanates, with sanitary sewer not available, an onsite sewage disposal system is required and shall be installed in accordance with Chapter 5 of the Monroe County Environmental Health Sanitary Code (PDF). There are several steps to obtaining approval from the Monroe County Health Department for an onsite sewage disposal system. We recommend contacting the environmental health sanitarian for your area for specific steps that need to be taken for your project. A general list of the order of things follows based upon the project.

  1. New Home Construction
  2. Existing Home Replacement Septic System
  3. Commercial Building Construction

Site Assessment

This is a site visit by the environmental health sanitarian that includes: soil borings (minimum of one but up to four) in the proposed area(s) of the onsite sewage disposal system, a general assessment of the property looking for such things as surface water, wells, general topography, existing or former buildings. The soil borings are to assess the native soil horizon for the top 4' of the soil as well as to determine the seasonal high water table (this does not mean there will actually be water the boring necessarily) in the area of the borings. Site assessments may require you to hire a backhoe and operator to complete excavations to 4' below the native ground surface elevation if the site has been filled or if obstructions are found within the top 4' at time of the initial site assessment. Sites will be denied if bedrock is within 4 feet of grade, unless portions of the site that can accept an original and replacement system are found with 4' of naturally occurring soil.

Plan Submittal

If the soils in the area of the proposed onsite sewage disposal system are not suitable (4 feet of naturally occurring sand) then plans, in duplicate, prepared by a licensed engineer or registered sanitarian (RS) in the State of Michigan or a registered environmental health specialist (REHS) as recognized and endorsed by the National Environmental Health Association shall be submitted with all applicable fees.


Following satisfactory review and approval of plans, if necessary, permits can be issued. If no plan review is necessary, the sanitarian assigned to the permit will develop an addendum to the permit with grades for the system and a benchmark at the site. The permits are good for one year from the date of issuance. An affidavit needs to be filed at the Monroe County Register of Deeds for all septic systems that require a set of plans. Prior to issuance of permits, all applicable fees shall be paid.


Following installation of the gravel bed and piping, including gravel cover over the piping, an inspection is required to be completed by the local sanitarian. Additionally, an inspection of the tank(s), any pumping equipment, alarms and the effluent filter are required. Finally, once the sand cover and berms, if necessary, are in place, a final inspection shall be completed by the local sanitarian. If the system required engineered drawings, the engineer or RS/REHS shall be contacted at the same times as the sanitarian to do their own inspections and a letter indicating that the system was installed per their plans is required to be sent to the environmental health division prior to final approval of the system. Please call 734-240-7900 to schedule appointments with the local sanitarian.

Further Information

Please consult an environmental health sanitarian for more information.

Watershed Pollution

Onsite Sewage Disposal Systems have been a subject of controversy that surrounds watershed pollution. The discussion stems from the belief that many older or improperly constructed systems have contributed to the heightened bacterial levels found in flowing bodies of water, bathing beaches, and a neighbor's backyard. The Monroe County Environmental Heath Division has the responsibility of enforcing state and local ordinances regarding onsite sewage treatment systems (OSTS) as defined by the Michigan Public Health Code P.A. 128, 1976 and the Monroe County Sanitary Code (PDF).

Renovations & Construction Additions

If you plan to renovate your home, add a pool or outbuilding and you are on an onsite sewage disposal system, make sure to check with your local municipality early in the process. In many instances, a construction addition to your home needs approval from the Environment Health Division (EHD) in regard to the distance of the septic system and well in relation to the addition prior to building permits being issued. You can print a copy of the Application to Construct an Addition (DOCX), fill it out and return it to the Environmental Health Division, with applicable fees. Based upon how thorough the records are for your property, if they exist, will determine whether a site visit will be necessary prior to approval of the addition permit. For fees, please contact the Environmental Health Division at 734-240-7900.


View a list of licensed contractors (DOCX).