Five Ways to Remove and Prevent Tree Roots in Sewer Lines


Root intrusion is one of the most damaging problems to discover in a sewer system. Roots thrive in sewer lines because the latter are well-ventilated and provide an excellent water source. While that's great for plants and trees, it can have a devastating impact on a sewer system.

Tree root intrusion can block sewer lines and affect the sewer system's hydraulic capacity; i.e., its ability to maintain or pass a given flow rate. A clogged sewer pipe will lead to slow-working drains, unpleasant odors caused by standing water within the drain line and damaging overflows.

How and why does root intrusion happen?

In old clay sewer lines, drain sections were connected by inserting a non-bell (hub) end of the pipe into the hub of the next section and filling the gap with concrete. With time, the concrete deteriorates, and roots grow through the openings and expand, damaging the piping. 
Roots can also grow through partially collapsed pipe or even rotted-out cast iron.  Deterioration of concrete or rotted-out cast iron is inevitable over time, allowing roots to grow through the openings.

If left untreated, root intrusion can eventually lead to a complete collapse of the sewer system. The roots on the outside of the pipe will encapsulate the pipe, creating pressure that will cause the sanitary system to collapse and shut down. At that point, the last resort would be to dig up the sewer line, costing thousands of dollars depending on location.

Let’s take a look at five ways to address a tree root problem.

1. Mechanically Remove Roots.

It is highly recommended to hire a professional drain cleaning service or plumber to solve tree root infiltration. Once you or your contractor identifies severe root activity within a sewer line, the roots should be removed with a mechanical, root-removal tool.

Cutters, nozzles, cable machines and jetters are often used for severe blockages. Snaking the line with a root cutter is one of the most common ways to remove roots. But be sure the heads and bits used on the ends are specifically designed for cutting out roots. Some heads can expand to adjust to the exact inside diameter of the pipe, completely cutting the roots down to the inside face of the pipe.

This function is particularly helpful. Many cutting tools will leave two inches of roots at the top because they do not fill the entire inside diameter of the pipe.

Keep the following in mind when snaking the line with root cutters:

  • Proper cable size: If you don't use the right cable size, you could either damage the tool or cause an injury. Say, for instance, you use a smaller snake. It could get caught in the roots, and you're left with a 20-foot cable stuck in the line. An improperly sized cable could get wound up or could even whip back, potentially leading to an injury.
  • Proper head size: As noted above, if you use the wrong head size, you won't get a full cleaning of the inside diameter of the pipe. Sizing is based on the pipe diameter. Most sewer lines will be three to four inches, but the main sewer line could be larger in commercial applications. A standard rule of thumb is to use a cable at least ¾ inch to an inch in diameter.
  • Maintaining mechanical equipment: Maintenance is key. If the root cutting head is dull or damaged, it won't be as effective. This also applies to snake cables. If a cable is kinked or bent, it could bind up and become ineffective because it has a weakened point. It could even break off and get stuck in the sewer or — worse yet — cause injuries.

2. Sewer jetting

Sewer jetting is another common practice for root removal. Jetters consist of a high-pressure water pump, water tank, hose reel, and ½-inch to 1-inch sewer cleaning hose. A sewer jetter is a great tool to remove piled-up root debris that remained in the pipe after using a root cutter.

Use a chemical after mechanically removing the roots.

Chemicals are best used as a preventive maintenance tool after mechanically removing roots from the sewer line. They open, clear, and prevent root-clogged drains and sewer lines.

It's important to understand that while chemical treatments will kill roots and prevent them from growing if used consistently, they won't immediately solve the problem. First, it is necessary to mechanically clear the blocking after root intrusion is identified to ensure that chemicals can effectively flow through the sewer line and adhere to the root mass.

3. Chemical treatments to consider:

  • Foaming root killers:  Some treatments include foaming chemicals made of metam-sodium. Special equipment may be required to create the foam that enters the pipe, in which case it is again recommended to hire a professional. Some foaming solutions can be poured into your toilet and flushed.
  • Copper sulfate crystals: This inorganic compound that combines sulfur with copper can kill bacteria, algae, roots, plants, snails, and fungi. These chemicals are formulated to eliminate and prevent root growth in sewer-type lines.
  • Hercules® R-D™ Root Destroyer is a special flake-like formula that prevents and stops root growth in external drain lines. Because this formula interacts with water, the drain line will need to be mechanically opened (snaked) to allow water flow if it is completely blocked. Once the line is open, a service tech can apply Root Destroyer at or near the root clog's location. Adding a treatment before bedtime will allow the Root Destroyer to work overnight without being flushed out too soon.

4. Install cured-in-place pipe lining
Pipelining offers an alternative solution to avoid digging up a damaged sewer line caused by root intrusion.

A cured-in-place pipe (CIPP) is a trenchless rehabilitation method used to repair existing pipelines.  A cured-in-place epoxy liner is applied to the inside of the pipe. Once fully cured, the lining acts as a new pipeline, sealing any opening or gaps to stop leaks and prevent future root intrusion.

5. Have your sewer line inspected every two years to identify a root problem

Be sure to have your sewer line inspected every two years, especially if you've had issues in the past. Hire a plumber or a drain-cleaning or sewer service company to 'scope' the line and identify any problems.

Scoping involves sending a remote camera down the line for a visual inspection. Depending on the findings, the company will recommend jetting or a drain cleaner to clear the line of any root growth.

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