Roots get into sewer lines through joints and cracks, usually in older clay or cast iron pipe, and grow into a mesh that catches paper and grease. The tell-tale sign is a main line backup that clears and then comes back every few months. Cutting or jetting clears them, a camera shows where they get in, and only repairing that joint stops them for good.
How roots get into a sewer pipe
Older sewer service lines were laid in short sections, with a joint every few feet. Over decades, joints shift and seals fail. Warm, moist air seeps out of the pipe into the soil, and a tree's fine feeder roots grow toward it. Once a hair-thin root finds the gap, it grows inside the pipe where there's water and nutrients, and keeps growing.
The result is a net of roots across the inside of the pipe. Water still trickles through, but paper, wipes and grease get caught, and eventually the line backs up.
Newer plastic pipe with glued joints is much more resistant, which is why root problems are most common in older homes. South St. Paul's sewer guidance names tree roots as a common cause of problems in private service lines.
Warning signs
- Backups that come back. The line gets cleared, works for a few months, then slows again. Roots grow back from what was left in the joint.
- Gurgling toilets and slow drains on the lowest level, especially when the washer runs.
- Water at the basement floor drain.
- A big tree between the house and the street. Not proof, but worth mentioning to the tech.
Backed up again? If it's the second or third time, ask for a camera inspection to find where the roots get in.
Call nowHow roots are removed
Cable with a cutting head
A rotating cable with a blade sized to the pipe shears roots off at the wall. It restores flow quickly and is often the first step.
Hydro jetting
High-pressure water cuts fine roots and flushes them away, and also strips the grease and sludge that roots trap. Jetting cleans the full diameter of the pipe, which tends to buy more time before the next cleaning.
Camera inspection
Once the line is open, the camera shows how many joints are letting roots in, how far out they are, and whether the pipe is cracked, offset or sagging. That tells you whether you have a maintenance problem or a repair problem.
What actually stops them
Cutting and jetting are maintenance. Roots grow back from the joint, so the honest choices are:
- Scheduled cleaning before the line backs up, if roots are getting in at one or two joints and the pipe is otherwise sound. Your backup history tells you the interval.
- Spot repair of the bad joint, if the camera finds one main entry point. A locator marks exactly where to dig.
- Lining or replacing the line, if roots enter all along the run or the pipe is broken in several places.
Root-killing products poured down the drain can slow regrowth, but they don't remove a root mass that's already there, and they won't fix the joint.
Is it covered by insurance? Whose tree is it?
Most homeowners policies treat root damage to a sewer line as a maintenance issue rather than sudden damage, so the repair itself often isn't covered. Water damage from a backup may be covered only if your policy includes sewer and drain backup coverage. Check your policy.
In Cottage Grove, the line between your house and the city main is the owner's responsibility, so roots in that line are yours to deal with, even when the tree is on the boulevard. If you suspect a city tree, call the city and ask. Don't assume.
What to ask when you call
- Will you cut, jet, or both, and why?
- Can you run a camera afterward and show me where the roots are coming in?
- Based on what you see, how soon will this come back?