Ask a plumber who runs a sewer camera every day what they see and the answer is a short list. Roots at a joint. Grease in a flat section. A belly a few feet from the foundation. An offset where the driveway crosses. Scale on the bottom of a cast iron run. A wad of wipes caught on something. Standing water that turns out to be a surcharged main. The same findings, in the same places, in house after house, because the same materials fail the same way and the same loads sit in the same spots. Knowing the list helps a homeowner understand a report and helps a new technician know where to slow down.
Quick answer: the most common residential findings are root intrusion at clay or cast iron joints, usually within reach of a tree; grease coating in kitchen branches and at flat sections of the lateral; a belly, most often near the foundation or under the driveway, from settlement; an offset joint at the foundation wall or a paving edge; scale and, in older houses, channeling in cast iron; wipes and non-flushables caught on an offset, a lip or a tap; a protruding or hammer tap at the main; and standing water from a surcharged main in wet weather. Each has a usual location and a usual outcome, below.
Roots at a joint
The most common finding in any house with clay or cast iron and a tree within fifty feet. Fine hair at a joint, a mat at a worse one, a full mass at the worst. Usually found in the yard between the house and the street, at the joints nearest the tree. Outcome: cutting for the symptom; a liner or a spot repair at the entry joints for the cause. The root guide covers the stages.
Grease
A pale coating thickening from the top in kitchen branches, and a band in the lateral wherever flow slows: a flat run, a belly, the connection at the main. Outcome: jetting, then a camera pass to find the flat section it will collect in again. The grease guide and the kitchen line guide cover it.
A belly
Standing water with a start and an end, most often in the first ten to twenty feet outside the foundation, where the trench was deepest and settled most, or under the driveway. Outcome: monitor if shallow; excavate and re-bed if deep and causing backups. The belly guide covers the decision.
An offset at the foundation or the driveway
The joint where the building drain meets the lateral at the foundation wall, and the joints at either edge of the driveway, are where differential settlement shows. A step, a crescent of gap, sometimes roots. Outcome: a spot repair if it is one joint; a liner if there are several. The offset guide and why lines fail at the foundation wall cover the locations.
Scale and channeling in cast iron
In any house old enough to have cast iron, scale on the invert is the normal finding and channeling the one that matters, usually in the kitchen line and the main run under the house. Outcome: scale is cleaned or left; channeling is replaced. The tuberculation guide and the channeling guide cover both.
Wipes on a snag
A pale tangled mass caught on an offset, a root, a lip or a tap. The wad is the symptom; the snag is the finding. Outcome: cable the wad; camera the snag; repair the snag. The non-flushables guide and the recurring clog guide explain why.
A bad tap at the main
The connection at the street, made in a trench decades ago, often a hammer tap with the lateral protruding into the main or a broken bell. Outcome: a rebuild with a proper fitting, usually part of any lining job. The tap guide covers it.
A surcharged main
Water rising toward the street with no obstruction, during or after rain. Not a defect in the lateral at all. Outcome: a backwater valve and a word with the utility. Reading standing water separates it from a blockage.
Where to slow down
For a technician, the list is a map: the first twenty feet outside the foundation for bellies and the foundation offset; the driveway edges; the joints nearest any large tree; the kitchen branch; the invert of any cast iron; and the connection at the main. Those are where the findings are, and an inspection that crawls through them and walks through the rest finds most of what there is. The field technician checklist puts it in order.
What is rarer than people expect
A collapsed pipe is uncommon on a line that still drains at all; most laterals that are inspected because of a slow drain have a partial obstruction rather than structural failure. A full break with soil visible in the pipe is usually found only where the drain has stopped completely or a sinkhole has appeared. Buyers who read about collapsed sewers worry about the wrong thing; the common findings above are what a camera will usually show, and most of them are maintenance rather than excavation.
Common questions
What is the most common sewer line problem?
Root intrusion at joints in clay and cast iron laterals, by a wide margin, in any house near trees.
Where do most sewer problems occur?
Near the foundation, at the driveway edges, near trees and at the connection to the main.
Is scale in cast iron a problem?
Light scale is normal. Channeling is the finding that means the pipe is failing.
Related guides
See interpreting sewer camera footage, the best sewer cameras for residential inspection, and what a sewer camera can detect.