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Yes, because the sewer may be outside the inspection scope
Yes, a home inspector can miss a belly in the sewer line, especially when the inspection does not include a sewer-camera scope. A belly is the common inspection term for a sag in the buried line, so it usually cannot be seen during an ordinary walk-through.
The inspection agreement matters more than the inspector’s job title. InterNACHI’s home-inspection standard describes a non-invasive visual examination of accessible areas and specifically excludes underground utilities and items. It requires inspection of the main water supply shutoff and water-heating equipment, but it does not list a camera examination of the exterior sewer lateral.
State rules and contracts can differ. Verify whether a sewer scope was ordered and which portions were inspected.
No sewer-scope finding is not a clear sewer line
If the report does not document a video scope of the exterior lateral, it generally provides no direct view of that buried pipe. Normal fixture drainage on inspection day does not establish that the lateral has continuous grade.
What a sewer camera can reveal
A sewer scope sends a camera through the lateral from an available cleanout or, sometimes, a roof vent. InterNACHI’s standard calls for recording the line, documenting visible defects, and noting inaccessible cleanouts.
Standing water is the main visual clue associated with a sag. That standard calls for reporting more than one inch of standing water as needing correction. Video may also show how long the camera travels through water and whether roots, offsets, restrictions, or damaged pipe are visible.
These observations can support a belly finding, but the video is not a survey of the pipe’s exact elevation. InterNACHI’s standard says a sewer scope is not technically exhaustive and does not identify concealed or latent defects. It also does not require the inspector to locate or mark a defect on the ground.
Why a belly may still be missed
Even when a scope was ordered, detection depends on several conditions:
- a usable access point and a camera that enters the relevant lateral;
- enough access to reach the suspected section rather than stopping at a restriction;
- a clear view not obscured by heavy debris or water; and
- a report and complete video that identify inspected and uninspected portions.
A brief pool of water should not be converted into a precise repair conclusion from video alone. Conversely, an unviewed section should not be treated as defect-free.
Practical bottom line
First, read the inspection agreement and report to see whether a sewer scope was included. If it was, review the full video, access point, inspected endpoint, standing-water observations, and stated limitations.
When a suspected belly could affect the property decision, a qualified sewer specialist can evaluate the recording and determine whether additional locating, cleaning, or site-specific testing is needed. That evaluation should distinguish what the camera actually shows from what remains unconfirmed.
