Tree Roots

How to Kill Tree Roots in a Sewer Line


If you’re noticing that your sinks or bathtubs are draining slowly, or if you hear a strange gurgling noise coming from your toilet, it could mean that your sewer lines have been invaded by tree roots. A small-scale root invasion will just annoy you, but if left untreated, this problem could cost you thousands.

Tree Roots are Attracted to Your Sewer Lines

Believe it or not, despite all the unsightly things that travel through your sewer lines, tree roots are naturally drawn to them. Your pipes are filled with water, oxygen, and all kinds of nutrients, so they’re prime real estate for a tree looking to plant its roots.

Typically, a crack or loose joint in a pipe will allow vapor to escape towards cool soil. The tree roots grow towards this in search of moisture and nutrients, forcing their way into the cracks of the pipe and making their home there. They’ll continue to grow, in some cases, until they’ve filled the entire pipe. The roots create a type of net that will catch anything you send down the line to create annoying clog that will slow your drainage system way down. If the roots are allowed to continue growing, they can apply enough pressure to collapse your sewer pipes, resulting in extremely costly damage.

Thankfully, there are ways to treat them yourself before they get totally out of hand. Get them under control without the help of a professional and with little to no plumbing knowledge. There are a couple of simple and affordable options available to you should you decide to tackle this problem on your own.

Rock Salt Can Kill Roots by Drying Them Out

Salt To Kill Tree Roots

The first method is to pour sodium chloride or copper sulfate, or rock salt, into your toilet. Pour a half pound of the salt into your toilet and flush as many times as you need to clean out the bowl, and repeat this process until you’ve flushed 2 pounds of salt into your pipes. Let the compound work its magic for 8 to 12 hours, avoiding flushing your toilet or running any water that will drain into your affected pipe.

Not only is it poisonous to plants, the salt compound acts as a highly-effective sponge, sucking away moisture from the roots so they’re not longer able to thrive. Doing this a couple of times a month will help keep your pipes clear of roots.

However, it is possible to eventually kill the entire tree and surrounding plants by using rock salt, so use caution if that’s not something you want to accomplish.

Foaming Root Killers Will Prevent Root Regrowth

Another DIY alternative is to use a foaming root killer, which is easier on your pipes and actually helps prevent root regrowth. Root killers contain an herbicide that kills tree roots upon contact and then leaves behind a residue that will discourage any new roots from snaking their way into your pipes. If you catch the problem early, you should be able to pour the root killer directly into your toilet, following the product’s instructions carefully. If you repeat this process a couple of times a year, you probably won’t have any more trouble with roots in your sewer line.

You Can Prevent the Problem Before it Starts

While the above methods of clearing out roots in your sewage lines are affordable in comparison to calling a professional service to do it for you, preventing the problem from ever occurring is obviously the cheapest route available to you.

If you’re thinking of planting anything in the future, you should find out where your utility lines are first. You can call a Before You Dig service to find out where you should or shouldn’t plant new trees so you won’t have to worry about their roots invading your sewer lines. Try to choose slow-growing plants or trees when taking on a landscaping project, making sure to plant larger trees at least 10 feet away from any utility line or far enough away that their roots won’t be able to reach your water lines.

It might mean that you won’t be able to plant that beautiful shade tree right where you want it, but it does mean that you’re less likely to have to spend thousands and thousands of dollars on pipe replacements.

8 thoughts on “How to Kill Tree Roots in a Sewer Line”

  1. Michael Cox says:

    Great information. I pulled the toilet off the floor today it would not flush. Found Sassafrass roots growing around the floor plate and down into the sewer. I worked quite a while on these but only managed to push them further into the pipe going to the septic tank.. Please let me know, will any of your above methods dissolve the small stringy roots lodged in my drain going to the septic tank ??? Really could use a call on this if you can 321-749-7300

    1. John says:

      I am having the same issue as well. There are roots coming from a maple tree outside the house, somehow thru the wall, under the linoleum and into the drain. I have cleaned it out about 5 years ago and again today. Any suggestions? Flushing down the drain won’t work, cause it will just pass the roots by. I did pour some weed killer on the roots last time as well as today.

  2. JAMES says:

    Intresting must try method soon .

  3. TH says:

    How do you kill roots in the pipe without killing the entire tree?

  4. renate auktor says:

    Is water softener salt the same, for this purpose?

  5. Dave Stedman says:

    I think I have roots blocking my soakaway line in a septic tank system. Will copper sulphate or a root killer destroy then? Must I suck out the septic tank first? What about Epsom salts?

  6. Rosie Robles says:

    My sewer is backed up. But it’s not coming into the house. But backing up in the streets. I’ve called a plumber out. He charged me $280. And didn’t fix anything. Pulled out some roots. He said water was in the pipes and couldn’t put the camera down. So what should be the next step

  7. Butch says:

    April 5, 2019 at 3:34 pm
    Mom & Dad lived in Colorado Springs. The city unknowing planted trees above the city sewer lines. They were told by a landscape company to put Bleach down their commode. This method kept new growth from coming into the lines.

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