Root killers for septic tanks, piping, drainfields? Advice on dealing with root invasion of sewer piping, drain piping, septic tanks, and septic drainfields.
This is part of our guide for homeowners who are planting trees, shrubs, gardens, ground cover, or other plants near a septic system and who need to know that can be planted near or over septic system components like the septic tank, distribution box, and drain field or soil absorption system.
Using Root Killers or Chemicals In Septic Drainfields, Mounds, Raised Beds, Septic Tanks and other Septic Components
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.
Planting fruit trees, or vegetables (or anything else edible) over the septic drainfield might produce food that is unsafe to eat: see SEWAGE CONTAMINANTS in FRUIT / VEGETABLES for details.
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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: 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: 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.
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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Frequently Asked Questions (FAQs) about septic system and drain piping root killers and invasion or blockage by tree, shrub, or other plant roots
Question: What liquid root killer can I use to kill the brush over my septic drainfield?
I have two septic tanks, the first seperates solids from liquid then sends the liquid to the second tank which has a septic pump that pumps the liquid UP to a drain field.
I want to kill brush over the drain field . The drain field is 1100 ft ABOVE my well . Is there a LIQUID root killer that I can use in this septic system as the copper pellets will never get up to the drain field and will sit in my seperator tank .
Can the copper pellets be ground into a powder - the powder mixed into a slurry that will be pumped to my drain field ? - firstname.lastname@example.org
Reply: we do not recommend brush or root killers over the drainfield - remove the plants instead
Take a look at PLANTS & TREES OVER SEPTIC SYSTEMS for details about planting over or near septic system components, and see USING ROOT KILLERS in SEPTIC FIELDS for our advice on the use of root killers in septic system tanks and drainfields.
Also see SEPTIC TREATMENTS & CHEMICALS for our explanation of the risks of using chemicals and other treatments in septic systems.
Question: Septic or sewer line treatment for redwood tree roots
What safe treatment is there for redwood tree roots...can I treat the end of root(s) I've exposed with something safe for aerobic bacteria in leach field? Can I 'paint' the end of the large root with something effective to kill only that root? Thanks. - Nanette
Nanette, my OPINION is that if you have large trees close to a septic drainfield their roots will continue to invade the field. If you kill off an individual tree root by cutting it back, the tree will send out new roots in its place. If you kill off enough roots to keep the tree out of the drainfield you'll likely kill the whole tree - a hazard of a different sort.
Thanks for your opinion. My redwood trees are 50 ft. away, but one of those roots has somehow navigated upward, I have it 'confined' in a 3" abs pipe, so I could 'treat it individually, if I knew what to do/what product to buy. The leach field is protected both upward and downward by cement-block retaining walls. It has lasted for 30 yr. until this year's 'root clog'. I have dug up the leach field, cleaned the rocks, replaced the drain pipe system which is a gravity system, but now with 'vertical inspection ports', as well as a 'cleanout'/drop for root treatment separate from cement septic tank. I just need to know how to treat this one invasive root. SIGH. What can I pour into the pipe containing the root to kill just this one invasive root, safe for the San Lorenzo River 60 ft. away?
Nanette: impressive that those trees sent out a 50 foot root. Look there are "root killer" products sold to dump into septic systems to try to kill off tree roots. They have the down side of leaving dead roots in the system, no permanent solution to the problem, and in at least some cases, contaminating the environment. With the river less than 100 feet from your septic system I'd prefer not to use chemicals.
I agree that I don't want to use chemicals, either, i.e., copper sulfate, etc.
I am currently looking for information on 'root deterrents', which seem to be a better avenue of research than 'root killers.' So far, it seems that salt may be the 'solution'. Let me know if you have any further suggestions re environmentally conscious root deterrents than only the 'physical digging down 10 ft.' unusable suggestion in my case.
In short, dumping salt or chemicals into the soil is not a recommended practice, and as I warned earlier, it's illegal in some jurisdictions. The risk is that you contaminate a well, groundwater, or other surface and subsurface waters, not to mention that root killers and root deterrent chemicals are a short-lived band-aid for a problem of roots invading septic systems.
I do not disagree nor not care for the advice given, but am looking for a long-term solution to my problem.
Some mechanical approaches to avoiding use of chemicals to attack invading tree roots are in the next Q&A.
Question: tree roots are invading our septic tank; we cut down the tree but roots continue to be a problem
I had an elm tree near the tank and when the tank was pumped we saw the roots had penetrated the tank. We cut down the tree but it keeps coming back, which I assume means the roots are still alive and may continue to grow into the tank. Any suggestions on keeping the roots from finishing off the tank? I didn't plant the tree; it was there when I bought the place. Thanks, Cole
Reply: some mechanical approaches to keeping problem tree roots out of drain pipes & septic systems
Cole, persistent tree roots around septic components are indeed an annoying problem. Quite a few readers ask about using root killers. Our OPINION is that there is a risk of contaminating the environiment, such products (and all septic treatments) are actually illegal in many jurisdictions, and worse, years ago when we tried the most popular products we found that the root killer was not a long lasting repair - two years after de-clogging by removing roots from an invaded pipe and using root killer we had to clear the pipe again.
Questions & answers or comments 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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