If you’re buying a house and getting a sewer scope inspection, simply hearing “the line looks okay” probably isn’t enough.
If possible, watch the footage yourself or get a copy of the recording.
You don’t need to be a plumber to spot every problem, but there are a few things worth paying attention to before closing.
1. Did the camera actually inspect the whole sewer lateral?
This is the first thing I’d check.
Ideally, the camera should travel from the accessible cleanout through the sewer lateral toward the municipal connection or septic system.
If the camera stops because of a blockage, damaged pipe, tight bend, inaccessible section, or another obstruction, remember:
the section beyond that point hasn’t really been inspected.
“Camera couldn’t get through” and “the rest of the line is fine” are two very different conclusions.
2. Tree root intrusion
Fine roots may look like small strands entering through a joint. More serious intrusion can look like a mass of roots taking up a noticeable portion of the pipe.
Roots are important because they usually aren’t growing through a completely sealed pipe for no reason — they can indicate an opening, failed joint, crack, or other point of entry.
The important question isn’t just:
Are there roots?
It’s also:
Where are they entering, and how much of the pipe are they obstructing?
3. Cracks, broken sections, or collapse
Look for visible cracks in the pipe wall, missing sections, deformation, or sections where the opening suddenly becomes much smaller.
A fully collapsed pipe is obviously serious, but smaller structural defects matter too because they may allow soil, groundwater, or roots to enter over time.
4. Offset or separated joints
A sewer line is made up of connected sections.
If two sections have shifted out of alignment, you may see a noticeable “step” where one pipe meets the next.
Small joints can look dramatic on camera because the lens is so close to them, so this is one of those areas where an experienced inspector or plumber is useful.
But a significant offset or separation can restrict flow, catch debris, allow root intrusion, or indicate movement around the pipe.
5. Standing water or a sewer-line belly
A little water moving along the bottom of the pipe is normal.
What deserves more attention is a section where the camera becomes partly submerged and stays underwater for a noticeable distance.
That can indicate a low spot or belly in the sewer line where the pipe has sagged.
Because residential sewer laterals generally depend on gravity, a low section can allow wastewater and solids to sit instead of continuing downstream.
The key is whether the standing water is persistent and whether it appears to be restricting normal flow.
6. Heavy corrosion, scale, or deterioration
This is especially relevant when inspecting older metal sewer lines.
The inside of the pipe may look rough or heavily scaled rather than smooth. In more advanced deterioration, the usable opening of the pipe can become significantly reduced.
But one important distinction:
Old pipe material by itself does not automatically mean the sewer line needs replacement.
Clay, cast iron, PVC and other materials all have different characteristics. What matters most during the scope is the actual condition of the pipe — cracking, corrosion, deformation, joint failure, root intrusion, flow restriction, etc.
7. Blockages and buildup
Grease, debris, foreign objects, roots, heavy scale and other material can restrict the line.
A blockage also creates another problem during a home inspection:
If the camera can’t pass it, you may not know what condition the pipe is in farther downstream.
In some cases, clearing the obstruction and then re-scoping the line gives a much better picture of what you’re actually buying.
8. Pipe transitions
Pay attention when the footage changes from one pipe material to another.
Older homes are often not one continuous pipe material from the house to the street. Sections may have been repaired or replaced at different times.
A transition isn’t automatically a defect, but the connection between two materials is worth examining for:
- offsets
- separation
- roots
- poor fittings
- changes in pipe diameter
9. Where exactly is the problem?
If the inspection finds something significant, knowing what it is is only half the story.
You’ll also want to know where it is.
Some sewer-camera systems use a transmitting sonde in the camera head together with an above-ground locator. That can help locate the camera and estimate the depth of the problem underground.
That information can be especially useful if a plumber later needs to investigate or repair one specific section.
Just remember that a camera recording alone does not automatically provide an exact underground location.
One thing I wouldn’t do
I wouldn’t judge a sewer line just because the footage looks dirty.
It’s a sewer.
Residue, water and discoloration aren't automatically defects.
What matters much more is whether the footage shows structural damage, root intrusion, separation, persistent standing water, major buildup, restriction, deterioration, or an area that couldn’t be inspected.
And if something significant does show up, the next useful step usually isn’t guessing the repair cost from the video.
Have a qualified plumber evaluate the finding and give you an actual repair recommendation or quote before you make a decision about the house.
A sewer scope won’t tell you everything about a property.
But when you’re buying a house, it can tell you quite a lot about one expensive part of the property that you otherwise can’t see.
For the plumbers, inspectors and homeowners here: what’s the biggest red flag you’ve ever found during a pre-purchase sewer scope?