Root invasion of a sewer line in Seattle WA (C) L Shields D FriedmanRoot Killers or Chemicals to Clear Drain Clogs?

  • ROOT KILLERS in SEWER LINES or SEPTIC PIPES - CONTENTS: Advice on the use of root killers or roto-rooters for septic systems. How should I get rid of roots invading my sewer piping or septic system piping and drainfield?
  • POST a QUESTION or READ FAQs about the use of root killer treatments to control trees, shrubs, or other plants whose roots invade the septic system piping or leachfield (soakaway bed)
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Are root killers an effective remedy for root-clogged sewer lines, drain lines, piping, drainfields?

Advice on dealing with root invasion of sewer piping, drain piping, septic tanks, and septic drainfields. This article describes approaches to removing and preventing root invasion and root clogging in sewer piping, septic piping, and septic drainfield pipes. At page top is a photo of roots growing into a clay sewer line connecting a Seattle WA building to the public sewer. Simply removing the roots or using a "root killer" won't fix a problem with recurrent clogging in a deteriorated or damaged sewer pipe.

This is part of our article series on sewer and septic installation, repair, maintenance and on planting trees, shrubs, or grasses or other plants on or near septic systems.

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Using Root Killers or Chemicals In Drain Piping, Sewer Pipes, Septic Drainfields

Planting the wrong things or in the wrong places can lead to the need for expensive septic system repairs. Planting trees, shrubs, and even some ground covers over septic system components are causes of septic system failure in the drain field, leach field, seepage bed, or similar components. When roots invade a sewer line (shown below) or septic tank, seepage pit, cesspool, drywall or sewer and septic piping, including soakbeds or drainfields, the clogging problem can be expensive. Simply removing the roots by any means: mechanical using a drain auger or power snake, or more slowly by trying to kill the roots with chemicals, might temporarily improve wastewater or sewage flow but the problem is not fixed.

Roots entering a clay sewer line in Seattle WA (C) D Friedman L Shields Breaking, deteriorating clay sewer line at a Seattle building (C) L Shields D Friedman

[Click to enlarge any image]

The photo at above left illustrates a modest root invasion at the joint in a clay sewer line at a property in Seattle, Washington. While roots continue to grow and occasionally slow or clog this pipe between a building and a city sewer, the underlying problem is an old, deteriorating clay sewer pipe whose joints are subject to heaving and breakage (photo above-right). Ultimately this line will need replacement. No amount of root killer, drain cleaner, or septic helper will repair a broken pipe.

Even where the sewer line or piping is not broken, just root-invaded through open joints, the most effective repair for root-clogging in drain or septic systems is by removing the root-invading plants themselves.

Tree, shrub or even some deep-rooting grasses and other plants will send out roots that find and are attracted by the nutrients in wastewater. Those roots find their way into the sewer or drain piping system through cracks in older pipes, particularly clay sewer piping or older cracking orangeburg pipe.

At clay sewer lines we often find roots invading the piping system at the hub joints that are not tightly sealed or at even older octagonal clay pipe sewer lines that had no water-tight connectors in the first place. Sewage effluent seeps out into the soil around these pipe openings that in turn invite roots to enter, grow, and even increase the damage to the pipes. Such root invasion is often undiscovered until building occupants begin to notice slow drains or worse, a sewage backup into the structure.

To repair root-invaded sewer piping, there are these approaches:

  1. Use a power auger to rip out roots from the pipes: you can expect the roots to re-grow and re-clog the piping system in 1-2 years, faster in some environments.

Clay sewer piping leak (C) Daniel Friedman Roots entering a sewer pipe at a joint (C) Daniel Friedman L Shields

  1. Excavate and repair or replace broken, cracked or heaved sewer or septic piping to seal off any leaks of wastewater into the surrounding soils. This repair is suitable for un-perforated sewer piping such as between a building and the sewer main or building and a septic tank. Replacing root-invaded pipes is not going to be a lasting repair if we are replacing perforated drainfield or soakbed piping in septic fields where invading-root plants are nearby.

    The photo above at left shows a too-common loose-fit and leaky connection between a cast iron house sewer main and a clay sewer pipe.
    See PLANTS & TREES OVER SEPTIC SYSTEMS for a series of articles describing what plants are ok and which plants are not safe to install over or near septic components such as soakbeds, leachfields, or cesspools.

    In the sewer line camera photo above at right you can see roots growing into the sewer piping at an open clay pipe joint. Removing a larger root and debris clog at this location can get the sewer working again but as you can see in the photo it is impossible to mechanically remove roots except from the pipe interior: the root stubs will grow back quickly.
  2. Remove aggressive-root plants that send deep roots into the sewer piping and that are planted too close to the septic fields or piping. The same article cited above will tell you the safe planting distances for common trees, shrubs, grasses and other ground covers.
  3. Try to kill aggressive-root plants by sending chemicals into the drain system. Products such as RootX®, Root Killer®, Robic Root Killer®, Foaming Root Killer®, and Hi-Yield Root Killer® are widely sold and have been tried by building owners for decades.

    In my first home in New York (back in 1969) we tried every imaginable septic system treatment, additive, and killer. What finally worked? We replaced the collapsing rusted-out steel septic tank, broken-up clay hub-type sewer piping, and we replaced poorly-constructed, failed drainfield built in saturated soils. It was not cheap, which is why like many consumers we were sorely tempted by the magic bullet approach of just pouring a magical product down the toilet. But there are some important limitations to the effectiveness, speed, and safety of this approach, as we discuss just below.

Using Root Killers to "Un-Clog" Septic Pipes or to "Prevent Septic System Clogging"

We advise against using chemicals or caustics to "kill" tree or other plant roots which may be present in or near septic system components. People fearing that roots will clog or have already clogged their septic system piping, particularly drainfield piping, are tempted to buy these products. This is another example of a "magic bullet" that does not work, is dangerous, contaminates the environment, and is illegal in some jurisdictions.

Root killers as environmental pollutants: OPINION: First, using a chemical to kill or to "prevent" invasion of roots in septic piping means you are pouring toxic chemicals and contaminants into the ground water - into the environment, and possibly right into your own or someone else's well and drinking water. This is a bad idea and is prohibited in many communities.

Root killers as a magic bullet to repair a septic system: OPINION: Second, if septic drainfield or other pipes are already clogged or partly clogged with tree or other plant roots, even if you killed the roots in the pipe you're leaving the clogging material.

Photograph of ammonia NOT being poured into a toilet

If piping in a septic system has become root-clogged, it is often the case that not only are the pipes clogged, they may be dislocated or even broken by the growing tree roots. You may find you've contaminated the environment, left the clog in place, and wasted your money since you'll still end up digging up the clogged line to replace it. [The photograph above is a simulation of pouring a chemical into the septic system through a toilet. Don't do this.]

Planting trees, shrubs, and even some ground covers over septic system components are causes of septic system failure in the drain field, leach field, seepage bed, or similar components. Planting fruit trees, or vegetables (or anything else edible) over the septic drainfield might produce food that is unsafe to eat:

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