Grease is the quiet blockage. It does not snag a cable, it does not show up as a dark mass, and it rarely causes a sudden backup. It coats the pipe wall layer by layer until the bore is a fraction of its size, and the first symptom is a kitchen line that drains a little slower every month. On a sewer camera it has a characteristic look, and once you have seen it you will not confuse it with anything else.
Quick answer: grease appears as a smooth, pale, waxy coating that thickens toward the top of the pipe and narrows the bore evenly, often with a crust of hardened fat at the water line. It hides joints and defects behind it, so a camera pass through a greasy line is a cleaning assessment, not a structural one. Cabling punches a hole through it; hydro jetting removes it. The structural inspection comes after.
What grease looks like on camera
The pipe wall disappears. Instead of a joint every few feet you see a continuous, slightly glossy tube that is narrower than the pipe should be. The colour is cream, tan or grey depending on what went down the sink, and the surface is smooth with occasional lumps where cooled fat has stuck. Because fat floats, the coating is thickest at the top and sides and thinnest on the invert where flow keeps it scoured, which is why the picture often shows a narrow slot of water at the bottom of a rounded tunnel. Under full LEDs it glares; dim the lights and the texture appears. Our guide on adjustable LED lighting explains why that matters so much on a pale wall.
Grease versus scale versus biofilm
Scale in cast iron is rough, rusty and concentrated on the bottom of the pipe where the water sits; it looks like coral, not wax. Biofilm is a thin dark slime that does not narrow the bore much. Grease is pale, smooth, and thickest at the top. The distinction matters because the cleaning method differs: scale needs a chain cutter or a descaling head, biofilm needs nothing, and grease needs heat and pressure. Pushing a chain cutter through a grease line smears it; jetting a scaled line cleans the scale’s surface and leaves the scale. Read cast iron vs PVC on camera for the material-specific picture.
Where grease collects
Kitchen branch lines first, because that is where it enters and where the pipe is coolest. Then the main lateral at any flat or bellied section where flow slows and fat has time to cool and stick. In commercial lines, the run between a kitchen floor sink and the grease interceptor is the usual culprit, and commercial kitchen grease line inspection covers that case. A camera pass should note the distance at which the coating starts and ends, because a grease band that begins at a specific point usually marks a belly or a change in slope that will keep collecting fat after cleaning.
How grease is cleared
A cable machine with a cutting head opens a channel through the grease and restores flow for a while. It does not remove the coating, and the channel closes again in weeks or months. Hydro jetting with a rotating or penetrating nozzle at adequate pressure strips the coating back to the pipe wall, and hot water jetting does it faster. Enzyme and bacterial treatments can slow re-accumulation but will not remove an established coating. After jetting, the camera goes back in, and only then can the joints and the pipe wall be assessed. The ranking of sewer cameras for jetting work explains the before-and-after workflow.
What the post-cleaning camera pass shows
Often, a belly. Grease collects where water stands, and once the grease is gone the standing water is visible. Sometimes a rough section of cast iron that the grease was smoothing over. Occasionally a joint that was leaking grease into the soil, which shows as a dark stain or a void at the joint. The point of the second pass is that the first pass could not see any of this. See bellied pipe on a sewer camera for what to look for.
Preventing the next buildup
Keep fat out of the sink, which is advice everyone has heard and few follow. Run hot water for a minute after washing greasy pans. Fix the belly or the flat section that the camera found, because grease will always collect there. Schedule a camera check on a known grease line before the slow-drain stage rather than after the backup, and keep the previous footage so the rate of buildup can be compared. For a kitchen branch too small for a full reel, the small-line cameras are the tools that reach it.
Common questions
Can a camera push through a grease line?
Usually, because grease is soft. The head comes out coated and the lens needs cleaning, and the picture past the first few feet is of grease, not pipe.
Does grease damage the pipe?
Not directly. It hides damage and it causes backups that flood fixtures, which is damage of a different kind.
Why does the grease come back in the same place?
Because the place has a belly, a flat run or a rough wall. Clean the grease, then inspect and fix the place.
Related guides
See the best sewer cameras for finding blockages, can a sewer camera find a blockage, and post-jetting camera inspection.