Tree roots naturally seek out water and nutrients, making sewer lines an inviting underground target. Even the smallest crack or loose joint provides an entry point for fine, hair-like root tendrils. Once inside, these roots proliferate into dense masses that impede wastewater flow, leading to blockages and potential backups. Addressing this intrusion requires a targeted strategy for eradicating existing roots and preventing future growth.
Chemical Root Killing Agents
The most common do-it-yourself solutions for root control involve chemical agents designed to kill the intrusive plant material. These chemical treatments are primarily available in two main forms, each with a distinct mechanism of action within the sewer pipe.
One traditional chemical option is copper sulfate, applied as a crystal or powder. When dissolved in wastewater, it releases copper ions that are toxic to the root tips. This action kills the portion of the root inside the pipe, causing it to decay and wash away. However, copper sulfate is dense and tends to flow along the bottom of the pipe, often missing roots that invade from the top joint, leaving a significant portion untreated.
A more advanced approach utilizes foaming root killers, which often contain the herbicide dichlobenil. This product expands dramatically upon activation with water, filling the entire volume of the pipe, including the top surfaces. The dense foam ensures comprehensive contact with all root mass surfaces, coating the roots above the waterline where most intrusion occurs. The active ingredient is absorbed by the roots, killing them and leaving a residual barrier that inhibits new root growth. Foaming agents are more effective for preventative maintenance due to their superior coverage compared to non-foaming chemicals.
Physical and Natural Root Control Methods
For blockages that are already severe, physical methods are often required to restore flow before any chemical treatment can be effective. Mechanical augers, often referred to as drain snakes, use a rotating cutting head attached to a flexible cable to bore through the root mass. This process provides immediate relief from the blockage, but it essentially prunes the roots, leaving stubs that will rapidly regrow within months.
A more thorough physical method is hydro-jetting, which employs a high-pressure stream of water (often between 3,000 and 8,000 pounds per square inch) to scour the entire interior of the pipe. This force cuts through the roots and removes accumulated scale, grease, and debris from the pipe walls. Hydro-jetting leaves a cleaner surface than mechanical snaking, significantly delaying root re-entry and regrowth.
A simple, natural alternative that some homeowners consider is rock salt, or sodium chloride, which acts by dehydrating the roots. When flushed down the line, the salt draws moisture out of the root structure, causing it to die. However, using rock salt in its crystalline form can sometimes worsen an existing blockage by accumulating in the pipe. Additionally, excessive salt can accelerate the corrosion of older metal or cast-iron pipes.
Safe Application Procedures
Regardless of the chemical agent chosen, safe and effective application requires adherence to specific procedures. Always wear appropriate personal protective equipment (PPE), such as gloves and eye protection, when handling chemical root killers. Apply the product when water usage in the home is at its minimum, such as just before retiring for the night.
This allows the chemical enough dwell time to remain in contact with the roots and maximize effectiveness. The application point should ideally be a dedicated sewer cleanout access, if available, ensuring the full dose reaches the main sewer line directly. If a cleanout is not accessible, the product can be flushed down a toilet nearest to the main line, using multiple flushes to carry the chemical into the plumbing system.
For preventative maintenance, chemical root killer applications are typically repeated on a semi-annual basis, often once in the spring and again in the late fall. This timing targets periods of active root growth and prepares the line for the winter months. When using copper sulfate, take caution to avoid pouring it down sink or tub drains, as this can corrode light-weight metal pipes in these fixtures.
Determining the Best Approach
The most effective strategy depends directly on the current condition of the sewer line. If the line is completely blocked or nearly so, the first step must be a physical intervention, such as professional hydro-jetting, to restore flow. Chemical agents are generally unable to clear a full obstruction because they cannot reach the roots without water flow to carry them.
For lines with only sluggish drainage or as a preventative measure, foaming root killers are considered the superior chemical choice due to their ability to coat the entire pipe interior. Their dichlobenil-based formula provides a more uniform and long-lasting treatment than the localized action of copper sulfate. While rock salt is inexpensive, its potential to cause secondary blockages and pipe corrosion makes it a less desirable option for long-term pipe health.
If root problems persist despite regular chemical maintenance, or if a blockage immediately returns after mechanical clearing, it suggests the pipe itself may be severely cracked or compromised. In these situations, do-it-yourself methods are insufficient, and a professional plumber with video inspection equipment is required. A professional assessment can determine if the problem is a minor root intrusion or a structural failure of the pipe that necessitates repair or replacement.