How to Tell If Tree Roots Are Growing in Your Sewer Line

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Ignoring clogged plumbing is never a good idea. But what if you’ve tried snaking and plunging your slow-draining sink—and perhaps even enlisted the help of a professional plumber—and you still can’t figure out what’s causing the clog? If you live in a house, it may be time to start looking into whether there are tree roots blocking your sewer lines. Here’s why that happens, and the signs that root-filled pipes are behind your plumbing problems.

What causes roots to grow in pipes?

Large trees can have extensive root systems: While some parts may be visible on the surface of your lawn, others sprawl out underground, searching for sources of water, oxygen, and nutrients—like cracked sewer lines. Even a small crack generates enough humidity to attract the roots of a tree on or near your property, allowing them to enter the pipe, and grow until it’s blocked.

But just because you don’t see a tree on or close to your property doesn’t mean you’re out of the woods. Even if a tree has been removed, its roots may remain inside your pipes for years to come.

How do I know if tree roots are in my sewer line?

Because your sewer line is underground and not easily accessible, you’ll need to pay attention to the signs that tree roots may be growing inside of it. These include:

Slow-moving drains in sinks, tubs, and/or showers

Gurgling sounds coming from toilet bowls

Backed-up toilets that don’t flush all the way

The smell of sewage and/or sulfur (rotten eggs) inside or outside your house, or coming from any drain

Lower water pressure

Whistling or banging sound coming from your pipes

A visible sinkhole in your lawn

Parts of your lawn have become waterlogged

What can I do about tree roots in my sewer line?

If it appears as though tree roots may be clogging your sewer line, you’ll need to decide whether it’s time to bring in a professional, or try one of these DIY options:

Foaming root killer

This is a root killer created specifically for this purpose, not the kind you’d use in your yard— though it’s also available at any hardware or home and garden store. Be sure that the product you purchase contains dichlobenil. To use it, pour the powder into your toilet bowl and flush. The foaming will start when the powder comes in contact with the water.

Rock salt

Get two pounds of rock salt, and split it up into four half-pound portions. Pour the first half-pound of salt into the toilet, and flush until it’s gone. Repeat this process with the remaining 1.5 pounds of rock salt, then leave the toilet alone—no flushing, dumping, etc.—for 12 hours. Try flushing the toilet again. If it’s still clogged, it’s a job for a professional.

Copper sulfate 

Although copper sulfate gets the job done, it’s also toxic to humans and other animals, and has been banned in some areas, including multiple counties in California. Be sure to check your local laws before using it. If you’re in the clear and decide to use copper sulfate, you’ll need to pour half a cup into the toilet, flush until it has washed out of the bowl, then pack up any people and pets residing in your household, and leave for a few hours while your home airs out.