Review the site and soil record
People often say “perc test,” but the public record may describe a soil evaluation, sewage permit, site plan, or onsite wastewater review. The purpose is to determine whether a proposed or replacement system can be designed for the parcel under the rules applied by the local health authority. Soil, slope, groundwater, available area, proposed home size, and required separation distances can all affect the answer.
For an existing home, review the original permit, site plan, later repair records, and any time-of-sale evaluation together. For vacant land, a nearby parcel’s result is not a substitute for an evaluation of the parcel and building plan you are considering.
Records to collect
- Search Washtenaw County’s well, septic, building-inspection, and soil-erosion records using the address and parcel information.
- Identify the approved system type, location of the tank and disposal field, design capacity, permit status, and any repair or replacement history.
- Ask whether a replacement area was identified and whether later buildings, drives, grading, wells, easements, or lot splits affect it.
- For vacant land or a planned addition, give the health authority an accurate concept for the home, bedrooms, water supply, and intended site work.
- Make contract deadlines and contingencies long enough for the required public review and qualified onsite work; seasonal conditions can affect timing.
What a passing result means, and what it does not
A favorable evaluation is tied to its documents, assumptions, location, and applicable requirements. It does not guarantee every house plan will fit, set the final construction cost, or resolve wetland, zoning, driveway, well, utility, and grading questions. Read the conditions and expiration or re-evaluation requirements shown by the responsible authority.
If the file is incomplete or the proposed use has changed, ask Washtenaw County Environmental Health or the authority with jurisdiction what new evaluation is required. A septic designer or installer can discuss system options and estimates only after the site constraints are understood.