Which trees to keep away from a sewer line
Updated October 30, 2026 · 2-minute read · Old House Sewer Lines
The trees to avoid near a sewer line are large, fast-growing species with aggressive roots: ash, sweetgum, poplar and cottonwood, lowland oaks, locust, willow, basswood, tuliptree, sycamore and many maples. That list comes from University of Tennessee Extension, which also says trees should go more than 10 feet from sewer lines.
The maples it singles out are red, sugar, Norway and silver maple, plus boxelder. The same publication is blunt on one point: there are no "sewer-safe" trees. Any species can send roots into a pipe that offers water, nutrients and oxygen, and an old house lateral offers all three. How much damage follows depends on the condition of the pipe, the kind of tree and the soil.
Why distance matters
Roots travel much farther than most owners expect. The sewer and water department in Traverse City, Michigan, puts the general rule at up to 2.5 times the height of the tree, with some species reaching five to seven times (Traverse City Tree Root FAQ). A 40-foot maple near the front walk can therefore have roots under the whole yard, including the path of the lateral to the street.
Roots do not hunt for pipe at random. Warm water inside the line gives off vapor into cooler soil, and roots follow that moisture to a crack or a loose joint, in winter as well as summer. Once inside, they grow in the air space above the flow, where there is oxygen, and the pressure of that growth can split the pipe and lead to collapse. The full process is covered in how tree roots get into sewer lines.
The pipe under older houses
Planting choices matter most where the pipe already has weak points. Many laterals serving older homes are clay or cast iron, FEMA notes. Clay pipe makers say installations more than 70 years old may have joints made in the field that do not meet current standards (NCPI), and those joints are where roots enter. Traverse City says PVC holds up better against roots because it usually has fewer joints and tighter ones. See clay sewer pipe for more on how old clay joints were made.
If you do not know where your lateral runs, find out before planting. A sewer camera inspection records distances from the cleanout, and the contractor can mark the route. Note that the 811 one-call service locates utility lines, not your own sewer pipe: UDig NY says member utilities do not mark private facilities on your property.
What to do with a large tree already in place
Removing a mature tree is not the only option, and nothing in the extension guidance calls for it. The usual path is to learn the condition of the pipe. A line with tight joints gives roots little to find. A line with open joints near a big maple will keep drawing roots in, which is why roots return after the line is cleared. Root cutting, chemical root treatment and pipe repair are jobs for a licensed contractor. Rye and Village of Mamaroneck codes require the owner to keep the lateral free of roots, so the condition of the pipe is the owner's concern either way.
Key facts
- UT Extension names ash, sweetgum, poplar, cottonwood, lowland oaks, locust, willow, basswood, tuliptree, sycamore and many maples as trees not to plant near sewer pipes (UT Extension).
- The same source says there are no "sewer-safe" trees and advises planting more than 10 feet from sewer lines.
- Roots can spread up to 2.5 times a tree's height, and five to seven times for some species (Traverse City).
- Entry points are cracks and loose joints; growth happens in the oxygen-rich space over the water.
- 811 locates utility lines only; UDig NY members do not mark private lines such as a sewer lateral (UDig NY).