A buyer puts an offer on a cottage in Birch Beach, south of Lexington. The inspection comes back clean. The purchase agreement moves forward. Then, three weeks before closing, the lender's underwriter asks for a septic evaluation report. Nobody on the seller's side saw it coming, because Sanilac County has no ordinance requiring one. The confusion that follows, over who orders it, who pays, and how long it takes, is the kind of delay that has nothing to do with the house and everything to do with a gap between what the county requires and what the mortgage requires.
That gap is the real story for anyone buying or selling shoreline property in this corridor, and it's easy to miss because most septic guides stop at the county line.
The Question Every Closing Timeline Assumes Away
Michigan is the only state without a statewide sanitary code. Instead, 45 local health departments each write their own rules for wells and septic systems, and only 11 of the state's 83 counties have adopted a mandatory Time of Sale or Time of Transfer ordinance requiring a septic evaluation before a property changes hands. Counties like Washtenaw, Grand Traverse, Emmet, and Charlevoix, along with Kalkaska and Manistee, fall into that group. Sanilac County does not.
That single fact leads a lot of sellers here to assume the septic system is a closing non-issue. It isn't, because a county ordinance is only one of two things that can force an evaluation onto the closing table. The other is the loan itself.
The County's Quiet Backstop
Even without a Time of Transfer law, the Sanilac County Health Department maintains an Existing Septic-Well Evaluation program that a buyer's lender can invoke on its own. This is not unique to Sanilac. Health departments across mid-Michigan describe the same mechanism: an evaluation of the septic system and well becomes required when a real estate financing institution asks for one, even in counties with no designated Time of Transfer program of their own. FHA and VA loans in particular tend to carry this requirement as a matter of underwriting policy, regardless of what the county does or doesn't mandate.
So the honest answer to "does Sanilac County require a septic inspection to sell a house" is that the county doesn't, but the buyer's financing very well might, and the seller who assumes otherwise is the one who ends up scrambling for an inspector with three weeks left on the calendar.
Same Corridor, Different Systems Block to Block
What makes this especially easy to get wrong along the Sanilac shoreline is that the answer changes house to house within the same few miles. This isn't a county-wide condition. It's a lot-by-lot one.
| Area | Water and sewer | What actually needs checking |
|---|---|---|
| Birch Beach subdivisions | Private well and septic | System age, tank condition, drain field capacity |
| Blue Water Beach Subdivision | City water and sewer, tied to an assessment | Remaining balance owed on the sewer assessment |
| In-town Village of Lexington lots | Municipal water and sewer | No septic question at all |
The Village of Lexington supplies municipal water to itself and to neighboring communities that purchase it, which is why in-town lots skip the septic question entirely while cottages a few miles south, in older platted subdivisions built mostly on private well and septic, do not. A buyer comparing two listings a mile apart can be comparing two completely different due diligence lists, and the listing sheet rarely spells that out.
The Shoreline Adds a Rule of Its Own
Even when a septic system needs nothing more than routine maintenance, the shoreline itself imposes a constraint that older lots weren't built around. Michigan sets a 150-foot minimum setback between a septic system and any Great Lakes shoreline, and that baseline applies statewide unless a county chooses to require more.
The subdivisions along this stretch of Lake Huron were platted decades ago, long before that setback was policy, and many of the lots are narrow by today's standard, some carrying well under 100 feet of shoreline frontage. On a lot that size, a failing drain field isn't always a simple swap. It can mean a redesigned system, an engineered alternative, or a request for a variance, all of which take time a thirty-day mortgage lock doesn't have. A buyer who assumes a failed inspection just means "call a contractor" hasn't accounted for what a tight lot does to that timeline.
The Well Question Sits Right Next to the Septic Question
Septic isn't the only system that deserves a second look on these lots. Sanilac County sits over the Marshall Sandstone, bedrock that a U.S. Geological Survey study of more than 3,000 wells across nine Thumb-region counties tied to naturally occurring arsenic. Across the nine counties in that study, medians ranged from under 3 micrograms per liter to over 16, and every county in the study, Sanilac included, had at least some wells test above the federal limit of 10. That study is older, but the bedrock hasn't moved, and a private well that has never been tested is a well nobody has actually confirmed is safe. For a buyer weighing a well-and-septic cottage against a municipal-service lot in town, that's a second test worth budgeting for, not just the one the lender might require.
A Bill in Lansing Could Eventually Change the Baseline
The patchwork itself may not be permanent. In January 2026, State Senator Sam Singh introduced Senate Bill 771 along with three colleagues, proposing Michigan's first statewide septic code. If it advances, it would replace the county-by-county system that currently governs Sanilac, and every other county without a Time of Transfer ordinance, with a uniform standard. Nothing about that bill affects a transaction closing this year, but it's a reminder that the rules a buyer researches today may not be the rules five years from now, and that today's absence of a county mandate isn't the same as a guarantee it stays that way.
What This Means If You're Selling
Getting ahead of the evaluation, rather than waiting for a lender to request it, is the difference between a closing that stays on schedule and one that doesn't. An evaluation typically runs $300 to $600 and takes a few hours, and having that report in hand before listing gives a buyer's underwriter one less reason to pause the file. If the system does need work, drain field repairs commonly run $5,000 to $15,000 and tank replacement $3,000 to $7,000, numbers worth knowing before a buyer's inspector delivers them as a surprise during negotiation.
What This Means If You're Buying
Ask two questions before writing an offer, not after: what does this specific lot run on, well and septic or municipal service, and is your loan type one that will require a septic evaluation regardless of what Sanilac County does or doesn't mandate. If the answer is well and septic, ask how much shoreline frontage the lot carries, since a narrow lot changes what a failed system actually costs to fix. None of this shows up on a listing sheet. It shows up when you ask.
A Few Questions Worth Asking Directly
Does every home on Lake Huron in Sanilac County have a septic system? No. Homes inside the Village of Lexington typically run on municipal water and sewer, while many surrounding subdivisions like Birch Beach rely on private well and septic. Some newer developments, such as Blue Water Beach Subdivision, have city water and sewer with an ongoing assessment attached.
Who pays for the septic evaluation? In most Michigan transactions, the seller covers it when a county ordinance requires it. Sanilac has no such ordinance, so when a lender requests one instead, it's a point for buyer and seller to negotiate directly, the same way any inspection cost would be.
What if my lot doesn't have room for a full-size replacement system? Talk to the Sanilac County Health Department early, not after an inspection fails. A narrow shoreline lot may need an engineered system or a formal variance request, and either one takes longer than a standard install.
If you're weighing a purchase or a sale along the Sanilac County shoreline, the specifics of your lot, your lender, and your subdivision's water and sewer setup all matter more than the county line does. Helm & Associates has spent more than two decades working these waterfront transactions across Michigan's Lake Huron and Lake St. Clair corridors. Request a free Home Value report or talk directly with our broker before you write or accept an offer, so the septic question gets answered on your timeline, not the lender's.
