Slow drains, poor flow, or complete lack of water are signs of major pipe problems, which are often caused by roots. Tree roots grow continuously unless there is something to impede them. Plumbers in Salt Lake City are all too familiar with the problem.
Once you have roots in pipes, they will continue to infiltrate and fill the space. Not only do the hair-like root masses get in the way, they also become traps for grease, toilet tissue, and debris, so water and sewer lines can quickly become blocked. When roots grow and expand, they also:
- Exert pressure at the joint or crack where they entered, potentially breaking the pipe or causing a total collapse.
- Affect some materials more than others, such as clay, although PVC pipe is less susceptible due to fewer, more tightly fitted joints.
- Find pipes because the tree follows a trail of moisture (vapors escape from tiny cracks, holes, and poorly sealed joints), during dry conditions.
Trees can grow relatively quickly. The potential for growth is the same above as it is below ground, given equal environmental conditions. According to Michigan State University, research in England found certain tree populations were more prone to causing building damage. Oak trees were the biggest culprits, with a 5.5:1 damage to tree ratio. This was determined by factoring that Oaks represent 2.1% of the tree population, yet caused in excess of 11% of the damage.1
Other species causing a disproportionate share of damage were Populus, Fraxinus, and Robinia trees. Fast-growing trees such as Norway Maple, Cottonwood, Boxelder, Sycamore, and Aspen have also been targeted by experts warning people of species best not to plant near sidewalks or sewer lines. Species of Magnolia have been included as well. A comparatively low level of damage was caused by Sorbus, Cupressus, and Prunus trees.
What Causes Roots to Grow into Pipes?
Tree and shrub roots grow into pipes via the same principles they do in the soil. To continue growing, they require sufficient levels of oxygen and water. A root system can travel as far as seven times the height of a tree, but most often extends about two or three times its height. In fact, a large tree may have thousands of feet of roots, enabling it to absorb nutrients, oxygen, and water from all around it.2
A typical root system has larger, permanent components to support and stabilize the tree. Smaller roots tend to be more flexible and temporary. These feeders and root hairs do most of the absorption at the top layers of soil and are more prone to infiltrating pipes and causing clogged sewer lines. However, growth rates aren’t constant. The water supply, availability of minerals, soil depth, and temperatures all affect growth; in a drought or cold weather, roots can travel far to seek moisture available in nearby pipes.
Here are some other factors that increase the likelihood of roots growing into pipes:
- Proximity: Distance is a primary defense, as the more yardage between a tree and pipe there is, the less likely the root can reach it. In a sidewalk study in Cincinnati, researchers found a 13% lower chance of tree roots being found under a sidewalk for every additional yard of lawn width.3
- Practice: People often prefer attractive landscaping and natural growth around their homes, which generally requires water. Anywhere there’s water, roots are likely to be present. Avoid fertilizing areas, such as near the foundation, where you don’t want roots to be; they won’t grow in dry Planting even small trees over or near known sewer pipe locations should be avoided as well.
- Maintenance: Roots are attracted to moisture, so any cracks or loose joints that allow moisture to escape can draw them closer. By maintaining your plumbing, roots can be deterred, especially if you correct leakage problems early or seal your pipes—but, even then, the slightest vapor escape can stimulate root growth around pipes.
Symptoms of Roots in Pipes
The sooner you act, the more likely it is you can avoid serious blockages and structural damage. The telltale symptoms of tree roots growing into pipes include:
- Slow flowing drains: If the water doesn’t drain as quickly, something in the pipes may be preventing it from flowing where it should—often a blockage by intruding roots.
- Noise: A gurgling sound from the toilet may indicate a blockage or disruption in flow. Water may also back up from the washing machine or bathtub. It’s most common in the early stages of a blockage; if your home is older, there’s a greater chance it’s due to tree roots in the pipes.
- Blocked/collapsed pipes: Roots in pipes will eventually cause a complete blockage. Once the pipe material is compromised, the structure may collapse, in which case the only option is to replace the sewer line.
- Visual proof: Unless you see a pipe with a root in it, the problem can’t be properly diagnosed. Professional plumbers can inspect a clogged sewer line using a camera, snaking it through the pipe until they see a root mass and the damage it has caused.
Avoiding Root Infiltration
The most cost-effective way to deal with root infiltration is to avoid it. People love the sight of mature, fully foliated trees in their neighborhoods, but often aren’t aware of what these trees may be doing to their pipes. To avoid expensive repairs later:
- Install tree root barriers: These plastic or fabric sheets can offer some protection, although roots have been reported to grow under a barrier and up the opposite side. Some fabric barriers are treated with an herbicide to prohibit root growth. To maximize effectiveness, the root barrier is installed by trenching the ground to a sufficient depth, but with care not to cause root loss or structural damage to trees.
- Lay sidewalk panels: In a few places, recycled plastic materials are used to manufacture rubber sidewalk panels less likely to buckle under the stress of tree roots. They’re also being promoted as more flexible, so joggers experience less strain on their joints.
- Treat pipe with root poison: There are compounds that kill tree roots without killing the entire tree. Not a permanent solution, this treatment delays the infiltration of roots, so it takes longer for them to be problematic.
- Seal existing pipe: In addition to sealing cracks and leaky joints, a plastic fabric and cement can be used to line the interior of the pipe, making it more difficult for roots to be drawn in by moisture and penetrate the material.
Disrupting the natural attraction of tree roots to moist pipes is the most effective means of prevention. However, you may be left with the only option of preventing a more serious and expensive problem. That means acting as soon as there seems to be a problem. Slow drains and gurgling toilets should be addressed immediately, as these may indicate a serious issue underground.