Tree Roots in Sewer Lines: Signs and Fixes

Why roots grow into old sewer lines

The sewer lateral runs from your house to the municipal sewer main. In many older Southwest Ohio neighborhoods, that pipe is clay tile laid in short lengths, with a joint every few feet. Some homes have cast iron, and homes from the mid-twentieth century may have a tar-and-fiber pipe sometimes called Orangeburg, which can soften and go out of round over time.

Any of these can develop weak spots. Joints loosen as clay-heavy soil swells when wet, shrinks in dry spells, and freezes and thaws through the winter. Cast iron rusts and flakes inside. Fiber pipe can deform. Small cracks and gaps appear.

A sewer line carries warm, nutrient-rich water, and a little of it seeps out through those weak spots. Tree and shrub roots follow moisture, and a fine root can work through a joint or crack. Inside the pipe, with a steady supply of water and nutrients, it grows quickly into a mat of fine roots that catches toilet paper and solids. The line keeps draining, just more slowly, until a blockage forms.

Roots rarely crack a sound, tight pipe. They use openings that already exist. That is why clearing roots without looking at the pipe often fixes the symptom for a season and leaves the cause in place.

Signs roots are in your line

Roots build up gradually, so the signs tend to be easy to dismiss at first.

• Slow drains in more than one fixture. If the tub, toilets and sinks all slow down together, the main line is likely partly blocked.
• Gurgling. A toilet or floor drain that gurgles when the washing machine or a bathtub drains means air is being pushed around a restriction.
• A basement floor drain that backs up. It is the lowest opening in the house, so it shows trouble first.
• Sewer smell in the basement, or in the yard near the line.
• A clog that keeps returning after it has been cleared.
• Changes in the yard. A strip of unusually green grass, or a soft or sunken spot over the line, can mean water is leaking out of the pipe.

Roots grow most actively in the growing season, so trouble often shows up in spring and summer. Not every one of these signs means roots, since a cracked, offset or sagging pipe can cause similar symptoms. The way to know is to look inside the pipe.

How a camera inspection confirms it

A plumber can run a small waterproof camera on a flexible cable into the line through a cleanout, the capped pipe near where the line leaves the house. The line usually gets cleared first so the camera has a clear view.

On the monitor you can see roots entering at joints, the condition of the pipe wall, cracks, separated or offset sections, scale in cast iron, and low spots where the pipe has sagged and holds water. A locator on the camera head lets the plumber mark the problem above ground and tell you how deep it is. Many plumbers record the footage, and you should feel free to ask to see it.

This matters because the repair depends on what the camera shows. A pipe with roots at one joint and good condition elsewhere calls for a very different approach than a pipe that is cracked and sagging along much of its length. Be wary of any recommendation to replace a sewer line that is not backed by video or another clear look at the pipe.

Find your cleanout ahead of time. If you do not have one, mention it, because adding a cleanout is often a sensible part of the work.

Repair options in general terms

Approaches fall into a few groups, and the right one depends on the pipe's condition, depth and location.

• Cutting and clearing. A machine with cutting heads, or high-pressure water jetting, removes the roots and scours the pipe. It restores flow, but the opening is still there, and roots usually return. For some lines, periodic clearing is a reasonable way to manage the problem, and for others it is only a stopgap.
• Spot repair. If the problem is one or two bad sections, a plumber can dig down and replace just those sections with new pipe. This works best when the rest of the line is sound.
• Trenchless repair. Some lines can be lined with a resin liner that cures inside the old pipe, or replaced by pulling new pipe through the old path. Trenchless work needs access points rather than a full trench, but it depends on the pipe being in suitable shape and not badly collapsed or sagging.
• Full replacement. When the pipe is broken, collapsed or in poor shape throughout, replacing the lateral with new pipe is often the lasting answer, either by open trench or a trenchless method.

Any work involving digging should include marking underground utilities by calling 811 first, and sewer repairs generally require permits and inspections. A plumber should handle both. For more on how these repairs are approached, see sewer line repair.

Reducing the risk of future roots

Once the line is repaired, a few choices help keep roots out.

• Know where your lateral runs. A locator can trace it so you do not plant over it.
• When planting near the line, choose slower-growing, smaller species and keep them well away. Willows and silver maples are well known for aggressive, water-seeking roots.
• Do not remove a large tree near the line without advice. Removing it will not always solve a root problem, and removal near a foundation has its own consequences.
• Keep grease and wipes out of the drain so the line stays clean and clear, and arrange follow-up cleaning if your plumber recommends it.
• If the line was only cleared and not repaired, watch for the early signs returning and have it checked again.

If you are unsure what your lateral is made of or what shape it is in, ask for a camera inspection, especially when you have had a backup or are buying an older house. Basic drain cleaning clears a line, and a camera tells you whether it needs more. The drains, sewer lines and basement backups guide places this in the bigger picture.

Frequently asked questions

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