Preparing known septic and sewer information for a buyer
Understand your legal obligations in Illinois when disclosing known septic and sewer issues to avoid liability and ensure a transparent property transfer.
The short answer
Illinois sellers must disclose material defects regarding septic and sewer systems if they have actual knowledge of them. You are not required to conduct new inspections or excavate systems to verify their condition. If you rely on information from licensed professionals or public authorities, you are generally not held liable for subsequent inaccuracies.
Defining Material Defects in Waste Systems
A material defect in a sewer or septic system involves issues that impact health, safety, or property value. Common examples include recurring backups, illegal connections, or known failures of the septic drain field.
Worksheet: Identify any professional invoices related to sewer or septic repairs. Categorize these as 'routine cleaning' or 'repair/replacement' to help distinguish between standard maintenance and material defects.
The Role of Prior Professional Knowledge
If you have received documentation from a local municipality or a contractor regarding your sewer connection or septic system, use this as the basis for your disclosure. This fulfills the obligation to disclose known information.
Planning Example: If a municipal inspector notified you of a needed lateral sewer replacement, that is a known defect. Failing to disclose this notification could create legal liability.
Managing 'As Is' Property Sales
The Residential Real Property Disclosure Act specifically states that the report does not limit the ability to sell a property in 'as is' condition. Disclosure is still required, but it clarifies the state of the property so the buyer can decide whether to move forward.
Planning Example: If you are selling a home with an aging septic system, disclose what you know about its age and past service. An 'as is' contract does not override the duty to provide the mandatory disclosure form.
Reporting Supplemental Information
If you learn about a sewer or septic issue after you have already submitted your disclosure, you must provide a written supplement to the buyer before the closing date.
Planning Example: If you uncover an issue during the pre-closing walk-through, document it in a supplemental disclosure immediately. This keeps the transaction transparent and protects your legal standing.
Checklist
- Locate all past service records for your septic or sewer system.
- Check local property files for any municipal sewer violation notices.
- Consult with a licensed plumber to clarify any ambiguous historical maintenance.
- Complete the disclosure form honestly based on your current actual knowledge.
- File a supplemental disclosure if new sewer system issues are discovered.
Common questions
Should I order a septic inspection before listing?
You are not required to do so under the Illinois Residential Real Property Disclosure Act. However, some sellers choose to do this voluntarily to gain information and potentially avoid post-contract disputes.
What if the sewer system is old but works fine?
Age itself is not necessarily a material defect. If the system is currently functioning and you have no knowledge of specific material failures, you do not need to label the system as defective.
Sources
- Illinois Residential Real Property Disclosure ActChecked October 12, 2026
- Illinois Condominium Property Act — 2025 editionChecked October 12, 2026
- IEMA-OHS — Real estate radon guidanceChecked October 12, 2026
- EPA — Real estate lead-hazard disclosuresChecked October 12, 2026
This guide is general educational content from SQFT IO, prepared with AI assistance. It is not legal, tax or loan advice. Talk with a licensed attorney, tax professional or lender about your situation. SQFT IO Illinois license 478.027617.