Time of Sale: Washtenaw County's Mandatory Septic and Well Inspection

What Time of Sale actually requires

The Washtenaw County Health Department's Environmental Health Division (705 N. Zeeb Rd., Ann Arbor, MI 48107-8645; (734) 222-3800) administers the Time of Sale (TOS) Program: before a home served by an onsite well and septic system changes ownership, both systems must be inspected and the results reported to the county. This isn't a generic home-inspection add-on -- it's a specific county requirement tied directly to the transfer of the property, and it applies regardless of how new or well-maintained the buyer or seller believes the systems to be.

The inspector has to come from the county's certified list

The inspection can't be performed by just any septic contractor: Washtenaw County maintains its own published List of Certified Time of Sale Well and Septic Inspectors, and the county sets minimum qualifications a septic professional must meet before being added to that list. If you're scheduling a TOS inspection, confirm your chosen inspector is currently on the county's list before booking -- an inspection from someone not on it won't satisfy the requirement.

Timelines: book early, and know the validity windows

The Environmental Health Division commits to completing its review of a submitted inspection report within five business days or less. Since a passed inspection's results are valid for 12 months, the county specifically encourages sellers to schedule the TOS inspection as soon as a home is listed, rather than waiting until it's under contract -- a failed inspection found late in a transaction can add real time pressure to a closing.

Scheduling itself has its own rule: inspection requests must be called in by 9:30 a.m. on the day an inspection is wanted, with the division making every reasonable effort to complete the inspection within 48 hours (excluding weekends and county holidays). If an inspection reveals a system that needs replacement, be aware the resulting sewage permit timelines are tighter than a standard new-construction permit: general sewage permits run up to two years, but a TOS-triggered replacement permit is valid for only six months -- plan the repair or replacement work accordingly rather than assuming the standard two-year window applies.

What this means for your purchase timeline

If you're buying an existing home on well and septic in Washtenaw County, build the TOS inspection into your purchase schedule as a core step, not a late-stage formality: confirm whether the seller has already scheduled or completed the inspection, check that whoever performs (or performed) it is on the county's certified list, and if a system needs replacement, budget for the tighter six-month TOS-triggered permit window rather than the standard two-year one. The county's eConnect online portal offers 24-hour access to check permit and TOS status directly.