Tree roots in the sewer line: signs, fixes and who pays

How roots get in

The pipe that carries waste from your house to the municipal sewer is called the lateral. In houses built before the 1970s or so, it is usually made of short lengths of vitrified clay, or sometimes concrete, cast iron or a tar-paper pipe known as no-corrode or Orangeburg. These have a joint every metre or so.

Sewer pipes are warm, wet and full of nutrients. Tree roots find the vapour escaping at a loose joint or a crack and grow towards it. A root hair enters, thickens and branches into a mass that catches paper and grease. As roots grow they force the joint further apart and can break the pipe.

Modern plastic pipe with sealed joints resists roots far better.

Where it is common

Older neighbourhoods with mature street trees: silver and Norway maples, willows, poplars and elms are known offenders, though any large tree near the lateral can do it. Much of older Toronto, Hamilton, and the pre-war and post-war parts of most Ontario cities fit the description.

Signs

• Drains running slowly throughout the house, not at one fixture
• Gurgling from toilets and floor drains
• A toilet that needs plunging often
• Water appearing at the basement floor drain when the washing machine empties
• Sewage smells in the basement or yard
• A backup that keeps returning months after the line was last cleared
• A soggy or sunken patch, or unusually green grass, along the line of the pipe

A backup every year or two at about the same season is a classic root pattern.

Confirming it

A camera inspection is the only way to know. A plumber or drain company feeds a camera through a cleanout and records the full length of the lateral. It shows:

• Where the roots are and how dense
• The pipe material and its condition
• Cracks, offsets, sags and collapses
• How far the problem is from the house, which tells you whether it is on your side or the city’s

Ask for a copy of the video and the distances. It is the basis for any quote, and for any discussion with the municipality.

The options

Cutting

A powered auger with a cutting head, or high-pressure water jetting, removes the roots inside the pipe. It restores flow the same day.

It does not remove the roots outside or close the opening. They grow back, commonly within one to three years, and often thicker. For some households, cutting on a schedule is a reasonable way to manage an old pipe. It is maintenance, not repair.

Chemical root control

Foaming root control products applied by a contractor can slow regrowth after cutting. Some products are restricted, and municipal sewer by-laws limit what may be put down a drain. Do not pour copper sulphate or household chemicals into the system on the strength of internet advice.

Lining

Cured-in-place lining inserts a resin-soaked sleeve into the old pipe and hardens it to form a new, jointless pipe inside. It needs little or no digging, usually just access at one or both ends, so driveways, gardens and trees are left alone. It works where the old pipe still holds its shape. It cannot fix a collapsed or badly sagging line.

Spot repair

Where the camera shows a single bad joint, that section can be dug up and replaced, or patched with a short liner.

Replacement

The lateral is dug up and replaced with plastic pipe, or replaced by pipe bursting, which pulls a new pipe through the path of the old one. It is the most complete fix and the most disruptive.

Work on the lateral needs a plumbing permit, and work under the road or boulevard needs the municipality’s approval.

Who is responsible

In most Ontario municipalities:

• The homeowner owns and maintains the lateral from the house to the property line
• The municipality is responsible for the part from the property line to the main

The details differ. Some municipalities will clear or repair blockages caused by roots from city-owned trees. Some offer grants or programs for lateral repair or for installing a cleanout at the property line. A few treat the whole lateral as the owner’s. Call your municipality when you have a blockage, before paying for major work. Many will send a crew to check the city side at no charge.

If a city tree is the cause, report it. Municipalities handle such claims in different ways, and time limits for notice can be short.

If it has already backed up

• Stop using water
• Keep clear of the sewage. It is a health hazard.
• Call a drain company to clear the line, and report the backup to the municipality
• Photograph the damage and call your insurer or broker
• Porous materials that sewage soaked are removed. Hard surfaces are cleaned, disinfected and dried.

See sewer backup: what to do.

Insurance

• Cleanup and damage inside the home from a sewer backup are covered only if you have the sewer backup endorsement.
• Repair of the pipe is generally not covered by a home policy, because it is treated as wear or maintenance.
• Service line coverage is an optional endorsement offered by some insurers that pays for repair or replacement of damaged underground service lines, sometimes including root damage. Check the wording.

Prevention

• Have the lateral camera-inspected if your house is older and has large trees, and before buying one
• Install a backwater valve to protect the basement. See backwater valves in Ontario.
• Know where your lateral runs, and avoid planting large trees over it
• Keep grease, wipes and paper towel out of the drains. They catch on roots.
• If you choose to manage roots by cutting, do it on a schedule instead of waiting for the next backup

Do not cut down a street tree. It belongs to the municipality, and removing or injuring it can bring a substantial fine.

More: sewage backup cleanup.