Tree Roots And Your Septic System: Why They're A Problem And What You Should Do

Posted on: 6 February 2015

If you have a septic line that's clogged, and you've got a tree growing within ten feet of the lines or tank, chances are the blockage stems from the roots growing into the line. It tends to be one of the more common obstructions with these systems. This needs to be addressed, but there is a right way and a wrong way. Here's what you need to know about why roots are so harmful and what you should do to fix the problem without damaging your septic line and the environment.

How do you know if roots are the culprit?

Even if you don't have a ton of trees in your yard or near the tank, they are notorious for spreading their roots a long way in order to reach a surplus of water. If you notice odors near your house, have a soggy lawn near the tank, and your tubs, toilets, and sinks are slow-draining, the problem could be roots. Another telltale sign that roots are the problem are little patches of green grass growing along the drain field. This happens where the roots have penetrated the line, and water is seeping out in those areas, keeping the soil watered all the times near those spots. 

In order to know for sure, a sewer contractor can typically perform a close inspection or use a camera to capture the culprit on film.

So, what's the problem?

Roots growing in the septic line. Tree roots growing into your septic line are a problem even before there are signs. You may think that a few small roots are okay and should be left alone. But anything that can penetrate the pipes can ultimately lead to costly repairs. Over time, the roots can completely block the line and you end up having to replace the whole system.

Roots growing in the drain field. While a portion of the wastewater gets treated before it leaves your septic tank, the rest of the treatment occurs in the drain field. The water percolates through the soil and gravel, getting further filtered until the bacteria and other contaminants are removed. When there are too many roots in the soil, this treatment process becomes hindered. And so it becomes necessary to have those roots removed as well.

How do you remove the roots?

Do not attempt to do this yourself. You'll need to contact a sewer contractor or plumber for assistance. Many products used to treat can't be purchased just anywhere, and you don't want to run the risk of using dangerous chemicals that will end up in someone's well or drinking water.

1. Manual removal. You can have the tree cut down, but that's a rather drastic solution. Plus, this measure alone doesn't really do anything to address the roots that are already there. Another option is to have the roots mechanically removed from the line. Drill machines and winches are commonly used. The benefit to this method is that the fix is immediate. But this alone also doesn't work as a long-term solution because the roots will grow back. In fact, they often grow back faster, thicker, and stronger than before.

2. Chemical treatment. Herbicides and other chemicals that will kill the root and spare the tree are a popular choice. For example, a contact herbicide will only kill the part of the plant that comes in contact with the herbicide. Copper sulfate has also been a popular choice for years, but it can destroy the beneficial bacteria in the tank and the surrounding leach field if not used properly. Also, copper is a heavy metal, which may be difficult to remove through the normal sewage treatment process, particularly when used in large quantities.

The most effective treatment for long-term prevention involves using both mechanical and chemical treatments by a skilled professional.

A septic contractor from a site like will be able to look at your lines and determine if the roots need to be mechanically removed before a chemical treatment is implemented. This is because if the obstruction is bad enough, any chemical or herbicide that is poured down the drain won't be able to reach the roots. While the roots might die quickly, it could take several months to a year for the roots to completely wash away, another reason why mechanical removal is great to use in conjunction with environmentally safe chemical treatments.