Does St. Charles County require a septic and well inspection to sell a home?
County mandate confirmedCounty-licensed inspector requiredVerified 2026-09-13
Yes. If you're selling a home in St. Charles County on a private sewage disposal system and/or private well, the county requires a compliance inspection before you can transfer ownership. You arrange it, it has to be done by an inspector licensed by St. Charles County, and the county issues a Certificate of Compliance once your system meets the code. If the inspection turns up violations, you'll need to correct them, or your buyer can take on that responsibility through a signed affidavit and an escrow account.
Source: the county ordinance, reviewed 2026-09-13. Two items below are pending directly with the county: the current licensed-inspector list and the accepted water-test panel. See open items.
Who and what this applies to
- This applies if your property is in unincorporated St. Charles County, or in a municipality that contracts with the county for this program. Check your address with the county's Permit Lookup Tool, or call Building & Code Enforcement to confirm.
- It's triggered the moment ownership of your property transfers, as long as it's served by a private sewage disposal system, a private well, or both.
- This is a county requirement, separate from and in addition to anything your buyer's mortgage lender asks for. See FHA, VA, and USDA requirements.
The steps
- Confirm your jurisdiction. Use the county Permit Lookup Tool, or call the Division of Building & Code Enforcement at (636) 949-7345, to confirm the program applies to your address.
- Hire a St. Charles County–licensed inspector. A Missouri DHSS state licence alone isn't enough for this program: the inspector needs a St. Charles County Onsite Wastewater Treatment System Inspector business licence. The county keeps the list.
- The inspection happens and the report goes to the county. The inspector submits the inspection report to the Division of Building & Code Enforcement.
- Pay the county review fee when the county receives the report.
- If it passes: the county issues a Certificate of Compliance, which serves as proof for the transfer.
- If it fails: correct the violations and re-inspect, or the buyer signs an affidavit accepting responsibility and an escrow account is established, funded to cover the estimated repair cost. The Director releases the escrow only once the system is brought into compliance. See your options if the inspection fails.
Costs and fees
| Item | Who pays | Amount |
|---|---|---|
| County review of the inspection report | Seller (per the ordinance) | $20, per of the county fee schedule |
| The inspection itself | Seller | Set by the inspector, not the county. A Missouri real-estate septic inspection typically runs $300–$700; confirm with a local licensed inspector |
| Private-well water test (if applicable) | Usually the seller for this program; the buyer's lender may also require one | Separate charge, through a private certified lab. The state lab does not do real-estate tests |
| Repairs, if the system fails | Negotiated between seller and buyer | Varies widely, from a minor fix to a full drainfield replacement |
Open items
This page states the ordinance as written. Pending directly with the county:
- the current list of St. Charles County–licensed inspectors and installers;
- the exact water-test panel the county accepts for the well portion;
- whether any incorporated municipalities that contract with the county run their own version of this program.
For anything decision-critical, confirm with the Division of Building & Code Enforcement at (636) 949-7345.
Exceptions
- Recent certificate or new system. No new inspection is required if a Certificate of Compliance was issued, or a new private sewage system and/or well was installed under county permit, within the last 180 days.
- Enrolled vacant buildings. A property on the county's Index of Vacant Buildings may be exempt, unless the Code Official determines in writing that the system is a danger to health or safety.
- Violations found but not yet fixed at closing. The Code Official can issue a temporary Certificate of Compliance, valid up to 180 days, so a sale isn't held up while repairs are completed.
Official authorities and documents
- St. Charles County Division of Building & Code Enforcement — 201 N. Second St., Suite 412, St. Charles, MO 63301 · (636) 949-7345 · runs the change-of- ownership inspection program.
- 2021 St. Charles County Private Sewage Disposal Code — (Transfer of Ownership), most recently amended by Ord. No. 25-085 (12-15-2025). The change-of-ownership inspection and the Certificate of Compliance; §500.310 itself is reserved. The $20 review fee is set separately at .
- OSCCMo Chapters 626 and 627 — the county inspector and installer business licence requirements.
- — (573) 751-6095 · state licensing of inspectors/evaluators () and registered installers.
Choosing an inspector and a repair contractor
For this program the inspector must hold a St. Charles County inspector business licence, not only a Missouri DHSS state licence. Missouri rule () also keeps the two roles separate: the licensed inspector who assesses your system must tell you that you are not obligated to use that same inspector for any repairs the assessment turns up. The choice of repair contractor is yours. See how we vet contractors.
Contractor matching comes next. We're assembling a verified list of St. Charles County–licensed inspectors and installers and a way to connect you to one. Until that's live, the county (636-949-7345) keeps the current list.
Sources & last verified
- (ecode360, current codification, most recently amended 12-15-2025). Reviewed 2026-09-13.
- — the $20 change-of-ownership inspection review fee. Reviewed 2026-09-13.
- St. Charles County — page and , sccmo.org. Reviewed 2026-09-13.
- (“Does the law require an inspection/evaluation of an OWTS prior to a real estate transaction?”). Reviewed 2026-09-13.
- ; . Reviewed 2026-09-13.
- — Drill Area 13's mandatory contaminant sampling for new/reconstructed wells west of Weldon Spring. Read in full, checked 2026-09-13.
Found something out of date? Email corrections@homecleared.com.
Common questions
- Who pays for the septic and well inspection in St. Charles County?
- The seller. Under the county ordinance, inspection fees are the responsibility of the seller (the ordinance allows the Code Official to permit an exception).
- What if the system fails the inspection?
- Either the seller or the buyer must correct the violations. If the buyer accepts responsibility, they sign an affidavit filed with the county and an escrow account is set up, funded to cover the estimated repair cost. The county releases the escrow only once the system is brought into compliance.
- Is a recent inspection still valid?
- The ordinance exempts a property from a new inspection if a certificate of compliance was issued, or a new system was installed under county permit, within the last 180 days.
- Does this apply if the home is on city sewer?
- No. The requirement applies only to property served by a private sewage disposal system and/or a private well. A home on public sewer and public water is not covered.
- Is there anything extra for a private well near Weldon Spring?
- Yes, but only if the well is new or being reconstructed — not for an existing, untouched well being sold as-is. Missouri well-construction rules set a separate, narrower zone (Drill Area 13) covering the part of St. Charles County west of Weldon Spring, near a former U.S. Army/Department of Energy site. A new or reconstructed well there must be sampled for known contaminants — including nitrate, uranium, and TCE — by an EPA- or state-certified lab, and the well is not certified until that sampling is complete. This is separate from, and in addition to, the county compliance inspection above.