The common failure findings are structural tank damage or a collapsed/missing baffle, a drainfield that is saturated or surfacing effluent, sewage backing up into the house, and a system whose permitted design (often tied to bedroom count) doesn't match how the house is actually used. Any one of these can stop a sale or force a repair negotiation.
Structural tank problems. Cracks, a collapsed lid, or a missing/failed baffle are straightforward fails: the tank can no longer do the settling job it's built for, and it's generally a repair the seller has to address or the price has to reflect.
Drainfield failure. Standing effluent, a persistently soggy field, or sewage odor at the surface means the soil has stopped accepting effluent at the rate the system needs. This is the expensive failure category, sometimes requiring a partial or full field replacement rather than a simple repair.
Backups into the house. Slow drains or backups during the load test point to a system that's already struggling under normal use, not just an old tank that needs pumping.
Undersized for the house. A system permitted for a smaller house than currently exists (an added bedroom, a finished basement used as a bedroom, an accessory dwelling unit) can pass a quiet-day inspection and still be functionally undersized for how the property is actually lived in. This is exactly the kind of thing a permit record catches that a walkthrough often doesn't.
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Yes. A system can appear to function on the day of inspection and still be undersized for the house, close to the end of its drainfield life, or missing components that only show up when checked directly rather than observed from the surface.
Not automatically. It's often a negotiation point: repair before closing, a price adjustment, or a seller credit are all common outcomes. See our guide on who typically pays for septic repairs found during a sale.
Not by itself. A full tank usually just needs pumping. It becomes a real finding when pumping reveals structural damage or when solids have already reached the drainfield.
Reviewed 2026-08-31 against the official sources linked above (where a source is cited) or, where none is cited, left deliberately general. Laws, lender overlays and local ordinances change; confirm current requirements with the county or state agency, your lender, and a licensed inspector before you rely on this for a closing.