The Root of the Problem

Trees and shrubs are among the most attractive features in a home or building exterior design. In fact, property values are often increased by the presence of a landscaped parcel of land with an abundance of trees and shrubs.

Not so attractive or valuable are the accompanying root systems, which can cause serious problems for plumbing drain lines.

But don’t blame the trees or shrubs. The roots become an issue for pipes because the trees and shrubs are merely doing what they are made to do by seeking water and nutrients in the soil.

The roots will break into the pipe only if there’s a problem with the material’s integrity, such as a bad joint or rusted pipe. Even tiny cracks can invite roots in. Root problems are especially prevalent in older homes in historic cities, where traditionally terracotta (or clay) was used for the pipes and joints often were made of cement.

It should be noted that roots can cause damage to the inside of sewer lines, not to water lines. If an incoming water line is broken by roots, it usually due to the roots deflecting the pipe when growing, stretching the pipe enough to break it; this will make itself known, usually through a high water bill or a soggy area in the yard, long before roots would have time to grow into the pipe.

When water leaks out of the drainpipe, the roots will sense it and grow toward it. The tree or shrub need not be immediately next to the drainage system for roots to affect it, as the roots will travel far to get nourishment. Droughts can cause even more damage, as that’s when the roots will try even harder to get to water.

If you’re wondering whether roots could be causing a stoppage, look at the surrounding yard. As a rule, tree roots can extend down up to two or three times the height of the tree and can extend out as far as seven times the tree’s height, depending on the type of tree.

Most roots are found in the top 6 to 18 inches of soil, where the water and nutrients are found. Root systems are composed of large permanent roots that provide support and stabilization, along with many small temporary feeder roots and root hairs, which are used as primary water absorbers.

Once the roots find a way into the pipe, they start growing larger, sending out the feeder roots and root hairs. If you do not deal with these roots immediately, huge hair-like root masses will fill up the sewer line and cause stoppages.

Tree roots in sewer lines are not always diagnosed quickly. As the roots grow, the water drains out of the home or building more and more slowly. By the time the roots have grown enough to cause a stoppage, they are a force to be dealt with.

Below are the most common methods for dealing with roots:

Chemical Treatment

Putting certain chemicals, such as herbicides, into the pipe will kill the roots but leave the tree or shrub unharmed. If using brand name herbicides, follow the directions on the packaging. There are also environmental concerns when using chemicals and you should check with your local environmental agency before using them.

Other chemicals used to kill roots include copper sulfate and rock salt. In both cases, the application is the same: a half cup flushed down the toilet. Note that the chemicals should go through only the toilet drain lines, never the sink or tub drain lines, as those are too thin for the corrosive effects of copper sulfate. The rock salt is also corrosive; use care with handling, as it can irritate skin.

The treatment could take a few weeks to completely kill the roots, depending on how big they are.

The downside is that even if the treatment gets rid of the root mass, it will not completely rid the pipeline of the roots, and they will simply grow back and will likely grow larger. Hence, the treatment will need to become more frequent, eventually leading to replacement of the sewer line.

“Surgical” Treatment

One option is to cut the roots out with a sewer machine or auger. However, like the chemical treatment, this solution would be temporary. Once the roots are into the pipe, they are there to stay. Which means you’d constantly be cutting them out, only to have them grow back bigger, doing more and more damage to the joints. (Picture what happens to a boulder when roots make their way through.)

Replacement Options

The only way to correct the problem of roots in the sewer line, short of chopping down the trees or shrubs that are causing the root problems (usually not the best choice), is to run a new line.

You can use a video pipe inspection system to locate where the roots are in the drain line to determine if only a section of pipe requires replacement or if the entire line needs to be replaced.

However, running a new sewer line can be problematic because of driveways, sidewalks, pavers, and landscaping – in some cases, expensive or irreplaceable work – that is arranged on top of where the sewer line runs.

In such cases, the line can be re-run by going into the existing line, cutting away the roots, and re-lining the inside of the pipe with plastic or fiberglass. This work is normally performed by specialty companies equipped for the task rather than traditional plumbing companies. The work can be expensive, but the cost should be weighed against the cost of cutting across and digging up driveways, sidewalks, pavers, and landscaping.

The new trenchless technology may work, which is where a replacement line is pulled through the existing line with special equipment that breaks up the old line while pulling the new line through. This should only be done by professionals.


The old saying “prevention is the best cure” holds true with roots in drain lines. And the best way to avoid roots getting into the lines is to run the appropriate material for the drain line. Plastic pipe PVC or ABS works best because the pipe is chemically fused to the fittings. This makes it water-tight, which means the roots won’t sense water in the soil and will have no means of breaking into the pipe.

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