How to prevent tree roots in a sewer line

There is no way to stop a root from looking for water, but root intrusion can be prevented in most cases. What you can do is make your sewer line a poor place to find it. Roots enter through gaps in joints and cracks. They arrive where trees are thirsty and close. So prevention has three parts: put the right trees in the right places, close the gaps in the pipe, and check the line often enough that roots never get a hold. This page is about stopping roots from starting. If they are already in, see foaming root killer and treatment options.

How do you keep tree roots out of a sewer line?

You make it hard for roots to enter and give them a reason to grow elsewhere. That means sealing joints with a lined or newer pipe, keeping thirsty trees well away from the line, installing barriers where trees must stay, and clearing small root growth early with scheduled cleaning.

No single step works alone. A new plastic pipe with tight joints resists roots well, but an old clay line next to a ficus will keep inviting them. The approach depends on how old the line is, what is near it, and whether roots have visited before.

How far should trees be from the sewer line?

Sources disagree, with common advice ranging from about 25 feet up to 50 feet or more for the most aggressive species. The root spread depends on the species, the soil and how dry the ground is. Treat any single number as a rule of thumb and measure from the pipe, not the house.

Trees that plumbers in Southern California commonly warn about include ficus, eucalyptus, pepper trees, willow and poplar. Better choices for planting near a line are generally smaller, slower trees and shrubs with shallow, non-aggressive roots, though you should confirm with a local nursery or arborist for your soil and the species.

A few practical rules:

• Find where the sewer line runs before you plant. A plumber with a locator can mark it.
• Keep mature thirsty trees away from the lateral, and especially away from the cleanout.
• Ask the nursery about root behavior, not just the size of the tree.
• Remember that roots travel: the tree that does the damage may be next door.

Does a root barrier help?

It can, in the right place. A root barrier is a vertical panel buried between the tree and the pipe that redirects roots downward or away. It works best when installed when the tree is young or when the line is new, and it must be deep enough to matter. It is less useful once roots are already established.

Barriers do not replace maintenance. Roots can grow under or around the end of a barrier, and a barrier does nothing for a root that is already in the pipe. Installing one near an existing tree needs care, because cutting large roots can harm the tree.

Can lining a pipe stop roots?

Often it can. Cured-in-place lining forms a new pipe inside the old one and seals the joints and cracks that roots enter through. If the old pipe still holds its shape, lining can end the cycle of cutting roots every year. It does not work on a pipe that has collapsed.

Lining is one of the trenchless methods. It needs a camera first, to confirm the pipe is in condition to be lined, and the pipe has to be cleaned before the liner goes in. It costs more than a single root cut, but many owners with repeat root clogs find it cheaper than clearing every year. Our pages on sewer pipe lining and trenchless pipe lining explain the method, and pipe lining versus replacement helps you decide.

If the pipe is Orangeburg, a tar-and-fiber pipe used until the early 1970s, it may be too soft to line, and the camera will show whether replacement is the better path.

How often should the line be cleaned to keep roots in check?

If roots have been in the line before, many plumbers suggest a scheduled cleaning every year or two, with a camera check to see how much growth there is. If the line has never had roots, a camera look every few years is a sensible check. The right interval is the one your own camera footage supports.

A hydro jet can clear roots and scour the pipe wall. A cable with cutting heads removes the root mass. Neither stops regrowth by itself, since the opening is still there. Chemical foams slow regrowth in some lines, but they do not repair the gap, and you should ask a plumber whether they suit your pipe.

What should you check in Los Angeles before cutting a tree or its roots?

Check the rules first. Street trees in the parkway are regulated: StreetsLA says a permit is needed before one is removed, trimmed or root pruned. Los Angeles also protects certain native species, such as oaks (except scrub oak), California sycamore, Southern California black walnut and bay laurel that are at least 4 inches across, and a permit is needed to remove one or to do work that may kill it, so cutting first can bring penalties.

The pipe is your side of the fence. The City treats roots in a house connection as the owner's job, even beneath the public sidewalk, and LA County takes the same view in its areas.

So the usual path is: get a camera inspection, find where the roots enter, talk to the City about any street tree, and deal with the pipe rather than the tree. Work on the lateral itself needs permits, and we'll arrange a local plumber who deals with that.

What if roots are already in the line?

Clear them first, then seal or replace the pipe if the camera shows damage. Prevention only works once the line is clean. A plumber clears roots with a cable or hydro jet, shows you the footage, and suggests whether lining, spot repair or replacement fits.

Read our guide to signs of tree roots in the sewer line to check what you are seeing, and how to get rid of roots in a sewer line for the removal methods.

For a camera check and a written quote on keeping roots out, request a price and we'll arrange a visit. You can also return to the LA Drain Works home page.

Questions people ask

How long does it take to protect a sewer line from roots?

A camera check and cleaning fit into one visit of a few hours. Lining usually takes a day or two of work, plus prep and permits. Replacing the pipe takes longer. Ask for a schedule that includes inspections, since those decide the real timeline.

What should I ask before I hire someone to deal with roots?

Ask whether the pipe can be lined, what the camera showed, and what happens if roots return anyway. Ask about permits and who pulls them. Get a written quote before any work starts, with barrier or lining options priced apart.

Do I need to be home for the visit?

Be there at the start so the plumber can reach the cleanout and see the yard. Tell us about locked gates, pets or trees that restrict access before the visit, and point out any tree you are worried about. Afterward, ask to see any camera footage.

Will a copper sulfate or foaming root killer prevent roots?

It may slow regrowth in some lines, but it does not seal the gap, and the right product depends on the pipe and local rules. Ask the plumber before you use one, and never pour strong chemicals into a line that might be broken.

Can I plant a tree anywhere if I use a root barrier?

Not necessarily. A barrier helps but cannot promise anything, and roots can grow around it. Keep thirsty trees well away from the line, find the pipe before you plant, and check the City's rules for street trees and protected species.