A hole in a sewer pipe is easy to describe and surprisingly easy to miss on camera. It is a gap in the wall, often on the invert of a corroded cast iron pipe or at the broken bell of a clay joint, and water has been leaving through it for as long as it has existed. Behind the hole, that escaping water has been carrying soil away, and the space it leaves is a void. The hole is a plumbing problem. The void is a ground problem, and it is the reason a small hole in a sewer line can end as a sinkhole in a driveway or a settling foundation corner.
Quick answer: a hole shows on camera as a dark, irregular opening in the pipe wall, usually with a rough edge, sometimes with soil, gravel or roots visible through it, and often with a stain or a scour mark on the wall around it. A void shows as blackness beyond the hole where the camera’s LEDs find nothing to light. Any hole needs repair; a hole with a visible void behind it needs repair promptly, because the ground above it is being undermined.
Where holes form
On the invert of old cast iron, where corrosion thins the wall from the inside until it breaks through; this is the end point of the process described in the channeling guide. At the bell of a clay joint, where a crack has spread until a piece falls out. At a point where a cable machine or a jetter nozzle has worn through a thin section. At the entry of a large root that has levered the wall apart. In Orangeburg, almost anywhere, because the material delaminates. And at old saddle taps and abandoned connections that were never sealed properly. The material you see predicts where to look, and the cast iron camera guide explains why the invert deserves the closest attention.
What the camera shows
At full LED power a hole can hide in the glare off a wet wall. Dim the lights and it appears as a dark patch that does not reflect. Its edge is rough, unlike a joint, and its shape is irregular. Look through it: if the LEDs light soil or gravel, the pipe is bedded and the hole is leaking into the ground slowly; if they light nothing, there is a void. A scour mark, a cleaner patch of wall around the hole where escaping water has washed the surface, is a reliable sign of an active leak. A self-leveling head keeps the invert at the bottom of the screen, which matters because invert holes are the most common and the easiest to pass over when the picture is rolling. Our guide on LED lighting in dark pipes covers the lighting technique.
Why the void matters more than the hole
Water leaving through a hole carries fine soil with it. Over months and years the soil around the pipe is removed, the pipe loses its bedding, and the ground above it loses its support. The first surface sign is a soft spot or a depression in the lawn. The next is a sinkhole, a cracked driveway slab or a settling corner of the house. A camera that shows blackness behind a hole is showing you the beginning of that process, and the finding belongs at the top of the report, not in a list of defects. Sinkholes and soft spots in the yard covers the surface side of the same problem.
Locating and recording a hole
Note the counter reading and the position on the pipe wall. Hold the head still so a clear still can be taken. If the system has a sonde, locate the head from the surface while it is at the hole; a hole with a void behind it is usually directly below a soft spot, and the surface locate confirms the connection. Record the pipe material and whether the hole is on the invert, the side or the crown, because an invert hole in cast iron is a corrosion finding and a crown hole in clay is a load finding, and the repair differs. Locating a sewer camera underground covers the method.
Repair options
A small hole in an otherwise sound pipe can sometimes be lined; the liner bridges it and seals it, though a void behind the hole can let the liner bulge outward during cure, and most contractors will want to see the footage first. A hole with a void needs excavation: the pipe is repaired or replaced and the void is filled and compacted, because a liner over an unsupported section will fail. A hole in channeled cast iron is a replacement, not a patch. In every case the camera goes back in after the work, and post-lining inspection explains what to check if a liner was used.
Common questions
Can a camera see a hole in the bottom of the pipe?
Yes, if the lights are dimmed and the head is self-leveling or the operator is watching the invert. Under full light on a wet wall it can be missed.
Does a hole always mean a void?
No. A hole in well-bedded pipe leaks slowly into the soil. A void forms when the leak is large or old enough to carry soil away.
Is a void an emergency?
It is a repair that should not be deferred. The ground above it is losing support every time the line is used.
Related guides
See what a sewer camera can detect, can a sewer camera detect a broken pipe, and the best sewer cameras for excavation planning.