Diagnosis

Tree Roots in Sewer Lines: Why Minneapolis Has So Many

By Minneapolis Sewer Line Repair · September 9, 2026 · 7 min read

Pull a camera out of a Minneapolis sewer lateral and the odds are good it comes back with roots on it. Tree roots in a sewer line are one of the most common problems in this city, and it isn't bad luck. It is the combination of what the city planted on its boulevards and what it buried under them.

The pipe: clay with a joint every few feet

Almost every house built here between 1900 and 1955 got a vitrified clay lateral — fired clay pipe in two- and three-foot lengths, each one slipped into the bell of the next and sealed with mortar or a tar compound. A 70-foot lateral has 25 or 30 joints. Clay itself is nearly indestructible underground; the joints are the weak point. A century of frost heaving the ground five feet deep, the house settling on its block foundation and the street loading the soil differently from the lawn has opened most of them at least a little.

A root does not need much. A hairline gap at a joint leaks a little moisture and nutrient-rich vapor into the soil, and a root growing through that soil turns toward it.

The trees: the boulevard program

Minneapolis has one of the most complete boulevard tree canopies in the country, and the boulevard is exactly where the lateral runs on its way to the main. The species matter.

• American elm. The original boulevard tree. Most were lost to Dutch elm disease in the 1970s and 80s, but the stumps and the roots stayed, and the survivors along streets like Nicollet and in Kenwood are enormous. Elm roots are aggressive and shallow.
• Silver maple. Planted everywhere as a fast replacement. Silver maple roots are legendary for finding water — they lift sidewalks and fill sewers.
• Green ash. The second replacement wave, now coming out across the city for emerald ash borer. Cutting the tree does not remove the roots, which keep growing for a season and then rot, leaving channels for the next tree's roots to follow.
• Linden and hackberry. The current planting choices. Better behaved but still trees, still growing roots toward moisture.
• Cottonwood and willow. Rare on boulevards, common in backyards along the creek corridors in Southwest and near the lakes. If one is within 40 feet of the lateral, it is in the lateral.

How a root gets from a hair to a blockage

1. A fine root enters an open joint and finds water and nutrients.
2. It thickens, and the pressure of a growing root pries the joint wider.
3. Side roots branch off inside the pipe and form a mat across the flow.
4. Paper, wipes and grease catch on the mat, and one laundry day the basement floor drain backs up.

By stage three the joint is broken, not just open. Which is why cutting the roots and walking away is a six-month fix.

Why clay, not the tree, is the real problem

People ask whether they should take the tree down. Usually no. A healthy boulevard tree is worth thousands in shade and property value, boulevard trees generally belong to the city, which has its own rules about removing them (check with the city first), and the roots of a removed tree keep working for a year anyway. The problem is the open joint. Fix the pipe and the roots have nowhere to go.

On a PVC replacement or a cured-in-place liner, the joints are gone. A properly installed liner has no joints for roots to enter.

Fixes that last and fixes that don't

If the camera shows roots at one or two joints and clean pipe elsewhere, a spot repair at $1,500–$4,000 solves it. If roots are at most joints, annual hydro jetting is a reasonable way to manage a line for a few years, and trenchless lining at $6,000–$15,000 is the way to be done with it — without disturbing the tree.

A note on root killers

Copper sulfate and foaming herbicide products kill roots on contact and slow regrowth. They do not close a joint, they can harm the tree if overused, and some products may be restricted for sewer use because the copper ends up at the treatment plant — check the label and with the city. On a sound pipe with light roots they are a fine supplement to jetting. On a broken joint they are a way to spend $40 a year not fixing a $3,000 problem.

Signs roots are already in the line

• Drains slow down a little more each month, then clear up after the line is snaked
• The floor drain gurgles or burps when the washer empties
• Backups that come back on roughly the same schedule each year, often in fall
• A snake comes back with fine, hair-like roots or a wad of root mat on the head
• A large tree within 30 or 40 feet of the path from the house to the street

Any two of these together are a good reason to get the line on camera.

Planting near the sewer path

If you are planting a new tree in the yard, find out where the lateral runs first. A camera with a sonde can trace it, or you can follow a straight line from the point where the pipe leaves the basement to the street as a rough guide. Keep large, fast-growing trees well away from that path. Smaller trees and shrubs with less aggressive roots are a better choice near the line. Boulevard planting is up to the city, so ask before planting there.

A tree you plant today won't reach the pipe for years. That is time to fix the joints, so when the roots arrive they find nothing to get into.

What to ask when roots are found

1. At how many joints are the roots, and how far from the cleanout?
2. Is the pipe still round and lined up, or are the joints cracked or shifted?
3. Is jetting enough for now, and how often would it be needed?
4. What would lining or a spot repair cost, and which joints would it cover?
5. Can I get the video before and after cleaning?

Common questions

Will cutting roots in the pipe hurt my tree?

Cutting the small roots inside a sewer pipe takes away a tiny part of a large tree's root system. A healthy tree is not harmed by it. Digging a trench through its main roots is a different matter, which is one reason lining is popular under big trees.

Can roots get into PVC pipe?

Rarely. Modern PVC has long sections and tight gasketed joints, so there is little for roots to find. Poorly installed joints or a break from settling can still let them in, but that is uncommon.

Do root-killing products harm the sewer?

Used as the label directs, they don't harm the pipe. They kill roots they touch and slow regrowth, but don't close the joint. Read the label and use only what it allows for sewer lines.

How often should a rooted clay line be scoped?

Every few years is a sensible rhythm for an old clay line under mature trees, plus any time it backs up. Comparing the videos over time shows whether roots are spreading to more joints.

The practical rule

Every Minneapolis house with a clay lateral and a boulevard tree should have been scoped at least once. If yours hasn't, that is the first call. Timing matters too: root growth peaks in late summer and backups follow in fall, which is why root season is a thing here.