Parcel jurisdiction
Confirm which county health department covers the parcel and whether any municipal requirement applies on top of the county process.
Michigan site work planning
Septic Permits and Soil Evaluation
The county health department for the parcel runs the process. Soil evaluation comes first, and it shapes everything after it.
Each county publishes its own current process. Start there, not with a general article.
(734) 476-1098Plan the next conversation
Use the guide below to organise questions, then confirm the details for the actual parcel and scope.
Explore excavation servicesA perc test is what most people call the step that decides whether a parcel can support a septic system, though counties in this region generally describe the process as a soil evaluation carried out through test pits or borings rather than a percolation measurement alone.
The evaluation is not a formality. It determines the system type, the field size, where the field and its reserve can sit, and sometimes whether the parcel can be built on at all.
This septic permits and soil evaluation guide explains the sequence, what the county reviews, and which parts belong to a credentialed installer or evaluator rather than to a builder. Septic permits and soil evaluation guide.
Jurisdiction, evaluation, application, inspection
Onsite sewage in Michigan is permitted at the county level through the local health department, so the process for a Washtenaw County parcel is not identical to one in Monroe, Wayne, Lenawee, Livingston, or Oakland County. Each publishes its own application requirements, evaluation procedures, installer rules, and inspection steps, and each updates them from time to time.
The common shape is consistent even where the detail differs. A soil evaluation establishes what the site can support. A design and site plan are prepared showing the system, the reserve area, the well, the structure, and the setbacks. The county reviews and issues a permit. A credentialed installer builds the system, and the county inspects it before it is covered.
The reserve area deserves specific attention. Counties generally require an area set aside where a replacement system could be built, and that area has to be protected on the site plan and in practice, which can constrain where the drive, the outbuilding, or the future addition can go.
What the county reviews
Soil evaluation
Test pits or borings assessed for soil type, depth to groundwater and restrictive layers, and suitability for the proposed system.
Application and plans
The application package, site plan, proposed flow or bedroom count, and the design, submitted in the form the county requires.
Setbacks and reserve
Separation distances to wells, water bodies, property lines, and structures, plus the protected reserve area for a future system.
Installer requirements
The county's rules for who may install, typically a registered or certified installer listed by that county.
Inspections
Inspection of the installed system before backfill and any as-built documentation required to close the permit.
Order of operations on a new parcel
1. Contact the county first
Ask for the current application package and the evaluation procedure before scheduling anything else on the parcel.
2. Evaluate the soils
Arrange the evaluation through the county's process. Results determine the system type and the usable field area.
3. Design and site plan
Lay out the system, reserve, well, and structure together so setbacks work before the house position is fixed.
4. Permit
Submit and obtain approval. Changes after approval go back to the county rather than being resolved in the field.
5. Install and inspect
The credentialed installer builds to the approved design and the county inspects before backfill.
Limits of this guide
Permit duration, evaluation methods, application contents, and installer rules are county-specific and subject to change. Confirm the current requirements with the county health department that covers the parcel; the county pages linked below are the starting point.
West Branch Builders is not a certified septic evaluator or installer and does not perform or certify soil evaluations. Those roles belong to the county and to the credentialed professionals it recognises.
A favourable evaluation is not a guarantee that the site plan will be approved. Setbacks, the reserve area, well placement, and the structure's footprint all have to work together on the same parcel.
Official sources — confirm current requirements with the office named for the parcel.
- Washtenaw County: installing a septic system — County application, evaluation and inspection process
- Washtenaw County septic and well application requirements — Application package contents
- Wayne County septic and onsite sewage program — County application, evaluation and inspection process
- Monroe County onsite sewage disposal program — County application, evaluation and inspection process
- Livingston County septic permits — County application, evaluation and inspection process
- EGLE groundwater discharge and onsite wastewater unit — State-level onsite wastewater program context
Turning this into a project conversation
If you are buying land or planning a build, get the evaluation and the county's requirements settled before the site plan is finalised. It is the cheapest point at which to discover a constraint.
Send the county and parcel details along with any existing evaluation, and the project conversation can be about what the site supports rather than what a general article suggests.
Related pages: Contact Us.
Questions to carry into the review
Is a perc test the same as a soil evaluation?
People use the terms interchangeably, but counties in this region generally rely on a soil evaluation from test pits or borings, assessing soil texture, structure, and depth to limiting conditions. Ask the county health department for the parcel what its current procedure is and who may perform it.
Who performs the soil evaluation?
That depends on the county. Some perform evaluations with their own staff, others accept evaluations from professionals they recognise. The county's own page or office is the reliable source, and it also confirms what has to be scheduled and when.
How long does a septic permit stay valid?
Validity periods are set by each county and do change. Confirm the current duration and any renewal or extension process with the county that issues the permit rather than relying on a number from a general source.
What happens if the soils will not support a conventional system?
The design moves toward an elevated or engineered alternative, which changes cost, footprint, and sometimes ongoing maintenance obligations. On a small or constrained parcel, it can also mean the proposed structure has to be resized or repositioned.