Tree roots in sewer lines

Tree roots from private property or boulevard trees can invade sewer pipes, as they thrive in the warm, moist air inside. Warm water in the pipe creates vapour that escapes into the cooler soil. Roots can sense even tiny changes in moisture and nutrients and grow toward these spots. They will push through cracks or joints in the pipe to reach the water and nutrients inside. This growth continues year-round, even when trees appear dormant in the winter.

Once inside the sewer pipe, roots keep spreading. If not removed, they can fill the pipe with many thin root masses. These roots trap fats, oils, grease, and other debris from the home, creating serious blockages. They can even cause your sewer pipe to break or collapse.

You can reduce the risk of costly damage with these steps:

• Plant trees wisely: Some trees are more likely to invade your sewer pipes. Avoid planting poplar, willow, elm, ash, or birch near sewer lines. Learn more below.

• Know your pipes: PVC pipes are more resistant to root intrusion than older clay or concrete pipes. PVC pipes have less joints that are tightly fitted and less likely to leak. Clay tile pipes are the most easily penetrated and damaged by tree roots. Concrete and no-corrode pipe may also allow root intrusions.

• Add root barriers: Physical barriers can be added to help prevent the roots from reaching your pipes. These barriers need to be deep enough to be effective.

• Schedule inspections: Ask a plumber for a television inspection to check for leaks or root intrusion. This can confirm root damage and determine its extent.

• Act quickly: Don’t ignore gurgling toilets or slow drains — they may be early signs of root growth. During drought conditions and in winter, tree roots travel long distances in search of moisture.

• Professional root control: Plumbers can apply treatments that slow regrowth for several years. Cutting roots with augers or saws may clear a blockage temporarily, but it often encourages faster regrowth, much like pruning a hedge.

Root removal and repair options

For root removal and repair services, contact a professional plumbing or sewer repair company.

• Mechanical removal: Augers, root saws, and high‑pressure flushers are often used to clear blockages in emergencies. However, cutting and tearing of roots encourages new growth that is often faster, thicker and stronger. Roots removed by augering are normally just a small fraction of roots inside the pipe.

• Chemical treatments: Safe herbicides can slow regrowth for 3 to 5 years.

• Pipe replacement: Severely damaged pipes may need repair or replacement, especially older clay tile pipes.

Different tree species have different water needs. Those with high water demand develop roots that track vapour from leaking pipes and invade them to reach water. The 5 species most likely to get into sewer pipes are:

• Poplar
• Willow
• Elm
• Ash
• Birch

Other trees and shrubs that can cause issues include maple, cottonwood, Russian olive, apple, pear, lilac, honeysuckle, and chokecherry.

Consider tree root spread

As a general rule tree roots will extend up to 2.5 times the height of the tree, and some species of trees may have roots extending 5 to 7 times the height of the tree.