Underground pipes (sewer, septic, and water lines) near mature trees are prone to root intrusion. Tree roots seek these pipes because they provide the necessary elements for aggressive growth: moisture, nutrients, and oxygen. Even a hairline crack or loose joint allows water vapor to escape, which roots detect and follow to the entry point. Once inside, the roots grow rapidly, creating a fibrous mass that traps debris and causes severe clogs and structural damage. Intervention is required to prevent costly backups and pipe failure.
Chemical Agents Used to Eliminate Roots
Chemical agents used to treat root intrusion work by killing the root mass, allowing it to break down over time, rather than by true dissolution. Copper sulfate, or bluestone, is a traditional and widely available contact herbicide. The copper ions penetrate the root’s cells, disrupting their structure and causing the root to dehydrate and die shortly after contact. This compound is typically sold in crystal form and flushed down the toilet to reach the affected pipe section.
Rock salt (sodium chloride) is another chemical option that works purely through dehydration. When applied in sufficient concentration, the salt draws moisture out of the root through osmosis. This process starves the root of water, inhibits nutrient absorption, and causes the roots to shrink and become brittle, making them easier to clear.
Specialized foaming root killers utilize herbicides like Dichlobenil. These products are formulated as a two-part mixture that foams up upon contact with water, completely filling the pipe’s diameter. The foam ensures the chemical coats roots growing along the top of the pipe, which gravity-fed crystals often miss. Dichlobenil works as a growth inhibitor, preventing new root cells from developing and offering a longer-lasting preventative effect against regrowth.
Understanding the Process of Root Elimination
Chemical treatments kill roots, but the physical mass remains in the pipe initially and must decay to be cleared. For copper sulfate or rock salt applications, typically two pounds of crystalline material are flushed down the toilet in half-pound increments. After application, water usage must be restricted for eight to twelve hours to allow the chemical to sit in the pipe and maximize contact time with the roots.
Foaming agents, often containing Dichlobenil, are typically applied in the late evening. A specific number of flushes activate the foam and push it into the sewer line, ensuring thorough coverage of the entire pipe interior. This method is preferred because the Dichlobenil residue remains, inhibiting future root growth for several months.
Safety and material considerations are paramount when using these agents. Copper sulfate can cause corrosion in older metal pipes and may harm beneficial bacteria within a septic system if used excessively. Homeowners should use it sparingly, though the copper only kills the root tips that absorb it and is generally safe for the tree above ground. Foaming root killers are considered safer for modern PVC pipes and septic systems, but product instructions must be strictly followed to avoid eye and skin irritation.
Non-Chemical and Mechanical Removal Options
When a pipe blockage is severe, chemical treatments are often too slow, requiring immediate physical removal to restore flow. Hydro-jetting is a highly effective mechanical method using specialized nozzles to spray water at pressures typically ranging from 3,000 to 4,000 PSI. This powerful stream cuts through the dense root mass and simultaneously scours the pipe walls clean of debris and small root hairs.
This high-pressure water method is superior to traditional snaking because it clears the entire pipe diameter, rather than just punching a hole through the blockage. However, hydro-jetting should only be performed after a camera inspection. The intense pressure can worsen damage in already cracked or compromised pipes, especially older clay or cast-iron lines.
Mechanical snaking uses a rotating auger or specialized root cutter blades for immediate removal. These cutters attach to a drain cleaning machine and shred the roots into smaller pieces that are flushed away. While effective for immediate clogs, this method often leaves fragments and fine hairs clinging to the pipe walls, encouraging rapid regrowth. Mechanical cutting is frequently followed by a chemical treatment to delay the return of the roots.
Preventing Future Root Intrusion
Long-term management of root intrusion involves addressing both the tree and the pipe structure. One structural approach is installing physical root barriers, typically made of plastic or metal, buried vertically between the tree and the pipe. These barriers redirect roots downward and away from the utility line without harming the tree, creating a protective shield.
Strategic planting is the simplest preventative measure. This involves selecting tree species with less aggressive root systems, such as Japanese maples or dogwoods. Large, high-water-demand trees like willows should be planted at least 20 to 30 feet away from underground lines. Keeping the soil well-hydrated near the tree can also discourage roots from seeking moisture in the pipe.
For pipes suffering from recurring intrusion, the most permanent solution is structural replacement or relining. Replacing older, jointed pipes (clay or cast iron) with modern, seamless PVC piping eliminates the entry points roots exploit. Alternatively, pipe relining involves inserting a resin-saturated liner into the existing pipe. This liner cures to form a new, jointless pipe within the old one, providing a smooth, root-proof barrier.