One of the main issues related to tree growth and potable water systems is damage due to the presence of roots in the piping infrastructure. This issue, also known as tree root infiltration, can be a nightmare for many private and commercial property owners.

While trees serve many essential functions on the property of many homes and buildings, like shading and cooling to landscaping and soil stability, their effect on buried infrastructure is rarely given any consideration. Unlike other stationary underground elements, such as sewer piping and utility conduits, trees are living organisms which grow and expand on a daily basis.

If left unsupervised, this expansion can eventually have disastrous consequences on buried potable water piping systems. Not only is tree root infiltration difficult to detect, but it can also result in costly repair and replacement operations.

Tree root infiltration depends on several factors including the species of tree, the rate of tree growth, the location of the tree in relation to the pipes, and the piping material. It is, therefore, essential that these factors are understood to minimize the threat of root infiltration and damage.

How Do Tree Roots Enter Potable Water Systems?

Tree roots naturally tend to gravitate towards sources of moisture. As such, buried potable water systems are a target destination of root growth. Not only do potable water pipes provide water, but they can also contain oxygen which is essential to tree growth.

When water pipes are in operation, they can occasionally suffer minor cracks or loose joints which can cause water to seep into the surrounding soil. This moisture is detected by the tree roots, causing them to grow towards the source. In pipes containing relatively warm water, tree roots may also be drawn toward vapor that may escape into the soil through loose joints or cracks.

The roots, which typically start as tiny elements, called hair roots, enter the piping through the closest available opening to reach the water in inside the pipeline. As the roots remain untreated inside the pipe, they continue to grow until they completely occupy the pipe’s interior.

Eventually, the roots will increase the size of the opening, causing more moisture and vapor to escape the pipe; thus promoting further root infiltration. Depending on the material, tree root expansion can even crack or rupture pipes from the inside due to the development of excessive pressure.

What Are the Consequences of Tree Root Infiltration?

One of the first and most common issues associated with tree root infiltration is pipe clogging or blockage. When the roots infiltrate the piping system, initial symptoms, such as reduced water pressure may be observed. As the roots continue to grow and multiply, the entire pipeline may become clogged, resulting in total blockage with little to no water flow.

Continued and unabated growth can cause the tree roots to apply excessive pressure to the pipe walls or joints, causing them to warp, bend, loosen, crack, or rupture. In some cases, tree roots can even wrap around and crush potable water mainlines.

This can eventually result in collapse of the piping system and flooding in the vicinity of the affected area. This flooding can lead to extensive property damage, especially if the location of the ruptured pipe is near the footing of a home or building. Saturated soil can lose its initial bearing capacity, causing the foundation to settle or sink. The resulting downward movement can ultimately lead to the development of cracks in the structure or, in extreme cases, structural failures.

Another sign of tree root infiltration in water systems is the presence of debris in the water supply. As the water traverses through the piping system, it may transport pieces of debris as a result of passing through the affected area. This debris may consist of sections of tree roots or even dirt particles.

How Can I Prevent Tree-Related Damage?

The most effective method of preventing this type of pipe damage is ensuring that no trees are planted near the location of potable water mainlines (and by extension sewer pipes, since tree roots are also attracted to these pipes as well). Although trees may be planted away from pipes, depending on the type of tree, the roots can eventually expand outward until they reach their destination.

As a general rule, large trees should not be located less than 10 feet away from water mains.

If trees are required for landscaping and aesthetic purposes, smaller trees, with shallower, less aggressive root systems can help reduce the probability of infiltration. In extreme cases, where it may be unfeasible to remove existing vegetation, licensed arborists can install products in the soil to help divert root growth away from water pipes.

Where tree root infiltration has already occurred and has been detected, a plumbing professional will need to be contacted to correct the problem. While open-trench methods are commonly used to access underground water piping, trenchless operations (i.e., techniques that require little to no excavation) are becoming the preferred method for diagnosing and fixing tree root issues.

One of the most common trenchless methods of inspecting pipelines for root infiltration involves using video imaging technologies, such as CCTV surveys, to view the interior of the pipe. (Read Using CCTV to Inspect Pipes.)

Once the extent of the damage has been assessed, the plumbing contractor can determine the best course of action for removing the blockage. Upon clearing the roots and other debris, trenchless repair methods, such as cured-in-place pipe lining (CIPP) can be used to seal cracks and ruptures without having to dig the surrounding landscape. (Read A Look at CIPP and Aging Drinking Water Infrastructure.)

What We've Learned About Tree Root Infiltration

While trees can be a valuable addition to residential or commercial properties, they can threaten the integrity of nearby water piping. The location of all vegetation on the property in relation to existing water piping should be carefully assessed to minimize the occurrence of tree root infiltration and associated pipe repair and replacement.