Do This To Kill Tree Roots in Your Sewer Line – Easy DIY

A slow/weak flushing toilet, slow draining bathtub or sinks that are backing up are usually caused by clogs in the sewer line. These clogs are often as a result of tree roots in the sewer line which restrict the flow of waste.

But how do tree roots find their way into sewer lines in the first place? And what can you do to prevent or kill tree roots in the sewer line?

tree roots in sewer line
Roots in a sewer line

Naturally, tree roots grow towards areas with moisture, nutrients and oxygen. All of these requirements are available inside the sewer line.

If there is a tiny crack or loose pipe joint in the sewer line, the waste will start to leak and tree roots will grow towards it. A tree root will force its way through the crack on the and grow into a huge root network inside the pipe if not controlled.

The problem will start as a partial clog but after sometime it will develop into a full clog meaning you cannot drain your fixtures. Fixing the problem at that moment will cost thousands of dollars.

The best way to kill tree roots in your sewer line is by using either rock salt or copper sulfate. Pour about 1 cup of each in the toilet and flush. Wait for 8-12 hours before flushing the toilet or draining any other fixture. Repeat after every 1 or 2 months to keep your sewer line tree root-free.

In instances where the tree roots network is well established and the process widening the crack on the sewer line, the homeowner will need to call a professional to perform a structural lining. This often involves the installation of a pipe sleeve to prevent leaks and deter more roots from growing into the sewer line.

You should therefore take preventive measures instead of having to deal with the actual problem. As long as you have trees in your property, this is a problem that will not go away and hence you need to always be on the lookout for any signs.

Here is a quick summary of how to kill tree roots in a sewer line:

  • Mechanical Root Removal: Rent or purchase a sewer auger or rooter machine from a hardware store. Follow the manufacturer’s instructions to carefully snake the tool through the sewer line to cut and remove the roots. This is a temporary solution and may need to be repeated periodically.
  • Chemical Root Killers: Copper sulfate is a common chemical root killer. Flush copper sulfate crystals down your toilet according to the manufacturer’s instructions. This chemical can poison and kill tree roots in the sewer line. Be cautious when handling and storing copper sulfate.
  • Foaming Root Killers: Some foaming root killer products are designed to coat the inside of sewer pipes, inhibiting root growth over time. Follow the product’s directions for application.
  • Biological Root Control: Some products contain natural bacteria that can digest and break down organic material, including tree roots. These additives can be flushed down drains periodically. Follow the manufacturer’s guidelines.
  • Preventive Measures: Periodically maintain your sewer lines with root control treatments to inhibit root growth. This is a preventive measure that can help minimize future issues.

Here is a lengthy answer to the problem:

How to Kill Tree Roots in Sewer Lines

There are actually several homemade remedies for killing tree roots in sewer lines meaning you do not need to call in a plumber. Plumbers will on average ask for $250 or more to fix the same problem.

1. Use Rock Salt


Rock salt will indeed kill tree roots in a sewer line. It does so by inhibiting the uptake of water and nutrients by the roots hence starving them off. Continuous absorption or high concentration of rock salt can kill the entire tree.

So, how do you use rock salt to kill tree roots without killing the tree itself? That has always been a challenge for most homeowners. You want the roots dead but the tree to thrive, yet the tree is fed by the roots.

According to Mr. Rooter Plumbing, flushing rock salt in crystalline form will indeed kill trees roots in your sewer lines but cause more problems as well. The argument is that the crystalline rock salt will add to the blockage and your sewer line will be even more damaged through corrosion.

The likelihood of the above happening is however at best minimal. I have seen rock salt used to kill tree roots in sewer lines plenty of times without any problems.

Here is how to proceed:

  • Pour 1 cup of rock salt in the toilet bowl.
  • Flush the toilet and wait 8 to 12 hours without flushing the toilet again or draining any other fixture.
  • Repeat once every 1 or 2 months.

Not only will the rock salt kill the tree roots in the sewer lines but it will prevent more from growing. This is why you need to do it periodically. Tree roots don’t die off easily.

If you don’t not want to use the rock salt in its crystalline form, you can flush it down as a solution. The only downside to this method is that most of the solution will just flow down the sewer line without proper contact with the tree roots.

  • Plug off your bathtub drain.
  • Pour about 20 pounds of rock salt in the bathtub.
  • Turn on the hot water.
  • Dissolve the rock salt in the hot water using a stick.
  • Unplug the bathtub and let the solution drain slowly.
  • Do not use the bathtub or drain any other fixture for the next 8 hours. You should aim to do this at night or when nobody else is in the house.

The hot salty water will be absorbed by the tree roots instead of the usual water and nutrients causing them to die off.

In case you ever notice trees in your yard start to wither or shed leaves, the roots have died off and the salt is having its effect on the trees themselves. At that time you should stop pouring more rock salt down the drain until after the trees look healthy again or there are signs of partial clogs.

2. Use Copper Sulfate


When absorbed, copper sulfate will kill tree roots in sewer lines thereby preventing them from clogging it. It is less effective compared to rock salt and will therefore rarely kill the trees.

Copper sulfate is readily available in your local home improvement store in crystalline form. Just like rock salt, copper sulfate has the potential to corrode your plumbing pipes.

Here is how to copper sulfate to kill tree roots in sewer lines:

  • Pour 1 cup of copper sulfate crystals in the toilet bowl.
  • Flush the toilet and wait a minimum of 8 hours for the trees roots to absorb it. This is means that you need not to flush the toilet or drain any other fixture for those 8 or more hours.
  • Repeat with a half cup of copper sulfate monthly or after 2 months. This is a more preventive measure to make sure that other roots will not grow in the sewer line.

As part of their natural stimuli, tree roots will always avoid copper sulfate. If you know the exact spot where the roots are attacking the sewer line from, you can treat the ground from there.

Dig a hole in the ground and sink a vertical pipe in it. Pour about half a cup copper sulfate crystals from time to time followed by hot water. The solution will penetrate the surrounding ground and tree roots will avoid that area thereby keeping your sewer line tree root-free.

Tree roots will typically die one week after treatment but it will take months for them to wither, break off and wash down the drain. Rock salt and copper sulfate are therefore not a quick fix to tree roots problem in a sewer line.

Foaming Root Killers vs Copper Sulfate

While copper sulfate will kill tree roots in your sewer line, it is more of a homemade/traditional method with its own limitations/disadvantages. But what is the effectiveness of using copper sulfate or rock salt compared to foaming root killers?

To understand the difference between these 2, let us first look at how a foaming root killer works. Unlike copper sulfate which flows along the sewer line, a forming root killer will foam once in contact with water and fill the pipe, coating it with a herbicide.

One advantage of the foaming root killer is that it fills the entire pipe, meaning it has the potential to kill tree roots attacking the sewer line from any angle. Since most tree roots enter the sewer line from the top, copper sulfate might not get to them since it flows at the bottom of the pipe.

Copper sulfate is however more lethal compared to the foaming root killer and will kill the roots within a week while it will take the foaming root killer months before killing the roots completely. During that time, there is the danger that the crack in the pipe will grow even larger than before.

The foaming root killer is however not harmful to the environment and also does not damage the plumbing. Copper sulfate is toxic to aquatic organisms and will kill the good bacteria in septic tanks as well.

If you are looking to only kill tree roots without the risk of the trees dying off in the process, a foaming root killer is your best bet. Both copper sulfate and rock salt can kill trees especially when high concentrations are absorbed by the roots.


1. Will bleach kill tree roots in a sewer line?

Yes. Bleach will kill tree roots in a sewer line but it is not very effective. Most of it will just flow past the roots, it kills the good bacteria in septic tanks and is also very corrosive, especially when you have steel pipes.

2. What is the fastest way to remove tree roots from a sewer line?

If you want to remove tree roots from your sewer line instantly, a professional will feed in an auger with blades at the front which will shred the roots into tiny pieces. You will then need to flush the line to wash down the roots. Hydro jetting is another alternative.

3. Will vinegar kill tree roots in sewer lines?

Yes it will. Mix 1 cup of each of the following: vinegar, baking soda, table salt and hot water. Flush the solution down the toilet. Do this often, perhaps once monthly. This is an ecofriendly and cheap way to kill roots in your sewer lines.

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