Key takeaways
- Roots commonly spread many times the width of the crown and can reach farther than the tree is tall.
- Older cement, clay or cast-iron sewer pipes that leak attract roots; newer steel or PVC lines are generally resistant.
- Do not cut large roots without an arborist's opinion. Roots anchor the tree and feed it.
- Call 811 before any digging near lines.
- Trees need room. A tree that outgrows its space is a planning problem as well as a pruning problem.
A raised sidewalk slab or a slow drain makes people think about the nearest big tree. Sometimes the tree is the cause and sometimes it is not. Here is what the International Society of Arboriculture says about roots and utilities, and what to do before anyone cuts anything.
How far do tree roots spread?
Most people picture roots as a mirror of the crown. They are wider and shallower than that. The ISA says roots commonly spread many times the breadth of the tree crown and can extend farther than the height of the tree. That is why a tree in the front yard can be near a sewer lateral in the street, and why trenching 'a few feet away' can still cut a lot of root.
In Northern Nevada, most of our soils are dry and the roots go where the water is. A leaking line, a lawn sprinkler zone or a downspout outlet is a draw. A big cottonwood or elm planted on an old lot will find it.
How do roots get into sewer and water lines?
The ISA explains the usual sequence. Older cement, clay or cast-iron pipes that have degraded may develop leaks. Moisture from the leaks attracts tree roots, which can penetrate and expand the cracks and damage the pipe further. New water and sewer lines made of steel or PVC are also generally resistant to root damage.
So when a plumber finds roots in a line, the useful question is why the pipe had a joint or crack for them to enter. A camera inspection of the line shows that. Removing the tree does not repair the pipe, and the pipe needs repair either way.
Sidewalks, driveways and foundations
Roots that run just under paving can lift it as they thicken. University of Nevada, Reno Extension notes that people should plan for a tree's mature size, since roots can damage nearby sidewalks and structures. The fix depends on the slab and the tree: sometimes the slab can be ground or replaced, sometimes the walkway can be re-routed, and sometimes the tree is the problem.
Big roots near a sidewalk are also a structural issue for the tree. A root that holds a large tree up is not a root to cut for convenience. Let an arborist look at what the root does for the tree before anyone takes a saw to it.
What to do before anything is cut
- Take photos of the lifted slab or the drain symptom, and note which tree is closest
- Have a plumber camera the sewer line if it is slow or backing up
- Call an arborist to look at the tree and the roots, not just the hardscape
- Call 811 before any digging; the ISA says accidental digging into buried utilities can mean costly repairs, injury or loss of life
- Check with your city if the tree or the sidewalk is in the public right-of-way
Repairs and digging near trees
The ISA also warns that repairing buried lines can hurt trees: excavation for that work can damage roots and harm or even kill the tree. If a line has to be dug, ask the contractor to plan the trench with the tree in mind, and ask an arborist to look before the digging starts.
Our root barrier service is one option for new trouble spots, and our root barrier guide explains its limits. When removal is the better answer, see tree removal. Battle Born Tree Service has two ISA Certified Arborists on staff, including ISA Certified Arborist WE-11728A.
Sources
- International Society of Arboriculture, Trees Are Good: Avoiding Tree and Utility Conflicts (read October 17, 2026)
- University of Nevada, Reno Extension: Tips for Healthy Landscape Trees (read October 17, 2026)
- International Society of Arboriculture, Trees Are Good: Why Hire an Arborist (read October 17, 2026)