Sewer System Basics: Root Control and Preventive Maintenance

Sewer System Basics: Root Control and Preventive Maintenance

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Root intrusion is one of the most significant problems to discover in a sewer system.

Roots thrive in sewer lines because they 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.

In old clay sewer lines, drain sections were connected by inserting the non-bell (spigot) 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.

Preventive measures

Professionals can help prevent root intrusion during installation by ensuring proper backfilling. The area around the pipe is compacted to help prevent the pipe from sagging or forming bellies in the line. Sagging can cause stress, leading to breaks, allowing roots to enter. 

The International Plumbing Code states: "Backfill shall be free from discarded construction material and debris. Loose earth free from rocks, broken concrete and frozen chunks shall be placed in the trench in 6-inch (152 mm) layers and tamped in place until the crown of the pipe is covered by 12 inches (305 mm) of tamped earth. The backfill under and beside the pipe shall be compacted for pipe support. Backfill shall be brought up evenly on both sides of the pipe so that the pipe remains aligned. In instances where the manufacturer's instructions for materials are more restrictive than those prescribed by the code, the material shall be installed in accordance with the more restrictive requirement."

While proper backfilling is a reliable way to aid in preventing root intrusion, 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.

At that point, the last resort would be to dig up the sewer line, which could cost the home or building owner thousands of dollars. Or pipe lining offers an alternative solution to avoid major excavation.

Manufacturers also offer various tools for cutting and cleaning out roots; however, it's important to follow certain steps to avoid damaging the sewer line. Here I’ll cover the basics of root removal, herbicides as a preventive maintenance solution and best practices when using them. 

Mechanical root removal 

Once severe root activity is identified within a sewer line, the roots must be removed with a mechanical tool. Cutters, nozzles, cable machines and jetters are often needed for severe blockages. 

Snaking the line with a root cutter is one of the most common methods. 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 feature is particularly helpful. Many cutting tools will leave 2 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 and it gets caught in the roots. You're left with a 20-foot cable stuck in the line. An improperly sized cable could get wound up or whip back, potentially leading to an injury. 
  • Proper head size: 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 3 to 4 inches, but the main sewer line in commercial applications could be larger. A standard rule of thumb is to use a cable at least 3/4-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 can bind up, resulting in injuries as well as ineffectiveness because it has a weakened point. It could even break off and get stuck in the sewer.

Sewer jetting is another common practice for root removal. It is a great method for removing piled-up root debris that remains in the pipe after using a root cutter.  

Chemical treatment

Chemicals are best used as a preventive maintenance tool after mechanically removing roots. 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. You must first mechanically clear the blockage to ensure that chemicals can effectively flow through the sewer line and adhere to the root mass. 

I suggest always recommending chemical treatment to your customer after you mechanically remove roots in their sewer lines. If left untreated, the roots will inevitably find their way back into the line again.

There are many options available on the market today. Some include foaming chemicals composed of metam-sodium. Foaming equipment may be required to create the foam that enters the pipe.  

Another effective chemical treatment are herbicides, an agent used to destroy or inhibit plant growth.

Herbicides like Hercules R-D Root Destroyer have copper sulfate pentahydrate as their main ingredient. This inorganic compound combines sulfur with copper to kill bacteria, algae, roots, plants, snails, and fungi. 

Herbicide root destroyer

Available at local hardware stores and supply houses, Hercules R-D Root Destroyer is a concentrated chemical product specifically formulated for the elimination and prevention of root growth in sewer lines. Large “root grade” crystals are blended with an active wetting agent, enabling the crystals to adhere to the root mass longer, dissolve slower, and effectively kill and eliminate root blockages. R-D helps eliminate overflow damage, sewage flow restriction and back-up odors due to root penetration.

Hercules R-D Root Destroyer helps prevent sump and ejector pump root damage and motor overload from pumping into restricted lines. When used as instructed, it is also safe to use in lines leading to septic tanks, cesspools and dry wells. It will not destroy trees, shrubs, or other vegetation. However, Hercules R-D Root Destroyer can not be used in Connecticut or some jurisdictions in California. 

I advise providing your customers with specific instructions after recommending a herbicide, always following manufacturer directions for application and use. 

Once the line is open, the solution can be poured into a toilet and flushed. Adding a treatment before bedtime will allow the Root Destroyer to work overnight without being flushed out too soon. 

How to use Hercules R-D Root Destroyer

House and building sewer connections: Use 2 to 4 pounds in a single application. Pour R-D into a toilet bowl closest to the sewer line, a half pound at a time, flushing after each pour to be sure all crystals will be carried to the sewer line. 

Another option is to remove the clean-out plug (usually located outside or in the basement) and pour the entire package directly into the sewer line. Flush it into the sewer with water. 

Note — Never pour R-D into sink or tub drains.

Use 2 pounds of R-D twice each year, and use the same method as described above for partial stoppages. To avoid wasting R-D by flushing it through a largely unobstructed sewer, apply it in the evening or during other low-flow periods for best results. Even small hair roots will absorb the chemical, preventing later blockage problems. 

Sewer mains: Sprinkle 2 pounds once a year into each junction and terminal manhole. Be careful not to obstruct free flow of sewage. 

Storm drains: Do not apply R-D during periods of heavy storm flow. When dry, introduce a controlled flow with a hose. You can use the same dose as in sewer mains. Serious conditions may require a larger, more frequent dosage.

Clean-up: Wash with soap and water after handling Hercules R-D Root Destroyer. Launder clothing after contact with R-D before wearing it again.

In most cases, several days should be allowed for the infiltrating roots to die, decay, and wash away after absorbing dissolved R-D.

Follow these safety practices when using chemicals for root control: 

  • Read all cautions and directions carefully before using a product.
  • Have proper PPE available.
  • Avoid contact with your skin, eyes, or clothing.
  • Store the chemical in its original container and keep it in a locked storage area. Do not reuse the plastic bag or empty container. Rinse plastic bags thoroughly before discarding in the trash.
  • Be sure the chemical you are using is permitted in your state or county. For example, Hercules R-D Root Destroyer is an herbicide; therefore, it must be registered with each state's EPA. Some states, such as Connecticut and certain jurisdictions in California, do not allow copper sulfate to be used as an herbicide.

Again, it is vital to remember: 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 blockage after root intrusion is identified to ensure that chemicals can effectively flow through the sewer line and adhere to the root mass.

About the Author

Sean Comerford is applications manager at Oatey Co. He is a third-generation tradesman with nearly 20 years of plumbing experience, including serving as the lead plumber for commercial/residential new construction, service and fire protection jobs.


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