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topic 22201

Killing roots with copper sulphate. What happens in drain/sewer pipe?

A discussion started in 2003 but continuing through 2018


Q. I have huge amount of roots in the pipes. I'm looking for a source of copper sulphate but affordable. Here in Canada I buy it from Home Depot at cca 10 $ per kg (2 lbf cca). When I put the copper sulphate in the drain- I assume it will be distributed in the pipe but unfortunately only at the bottom of the pipe. I tried to speak with Iron Out people about this but was difficult to get an answer. When these blue granules are in the pipes, they stick to the cracks and they dissolve gradually but some of them will be flushed away? then the presence of the remaining ones will create a negative environment for the roots? I want to know what is happening there in the sewer pipe and also to find a source of copper sulphate for roots but cheaper- say at CCA 2 $ per Kg. Anybody knows?Please answer.

Mike M
[last name deleted for privacy by Editor]
- London , Ontario, Canada


A. Mike,

If you don't mind the pun, the Root of Your Problems lies, I think, in the sewer pipe connections ... which I'm guessing have concrete bell and (poorly fitting) spigot connections. Then the roots will search for water and seep in insidiously.

Solution ... replace with plastic piping, cemented construction ... or to clean/kill the roots, heck, you'd have to block off the end of the pipe and let the copper sulphate RESIDE inside the pipe for a day or so making sure, of course, that the pipe is nicely filled up.

freeman newton portrait
Freeman Newton
White Rock, British Columbia, Canada

(It is our sad duty to
advise that Freeman passed away
April 21, 2012. R.I.P. old friend).

Copper Sulphate 50 pounds


A. Hi Mike. I see a 50-pound bag for about $2 to $2.50/pound on Amazon =>

which gets you halfway to the price you're looking for, but if you want it for $2/kg I think you'd need to buy it in industrial quantities. I suspect that people may not be able to buy this algae/root killer (and fish killer if overdosed) in industrial quantity without permits. If your pipes are so damaged that you literally need copper sulphate to be pouring out the cracks to keep the water flowing, I'd call in someone like Roto Rooter to cut out the roots, and try a small quantity of copper sulphate to deter new growth, and plan on replacing the drain pipe soon. Good luck.

Ted Mooney, Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey


Q. I am a home owner who is having a problem with my septic tank. I was told that I could use copper sulfate [linked by editor to product info at Amazon] in my tank to get rid of roots. Is this so? I have animals that would be close to the septic area, so would it be harmful to them? Does copper sulfate dissolve the tree roots? Would it dissolve any other type of clog that might be in the tank or field lines. Please help me.

Thank you,

Joan M Watson
home owner - Dyersburg, Tennessee


A. Copper sulphate doesn't exactly dissolve roots, Joan, it's a specific biocide that deters them and kills some other green things, mostly chokeweed and algae. Dead things eventually rot away, and I think that is what would happen. If the animals can't get to the septic tank I don't see any danger to them, and it isn't harmful to most green things.

Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey


Q. I was told to get copper sulfate, to treat my cactus garden' I bought some blue crystals but there no instructions on it. How and in what amount do I mix. I do not want to kill any cactus or any trees. Can you help me. we have a fungus and some root rot.

Nancy Schrader
Hobbyist - Morgan, Texas


A. I found this information link [Oklahoma Co-operative Extension Service] on the web, it might help in understanding how Copper Sulfate works and how much to use.

Chris Gredvig
- Salt Springs, Florida

Ed. note: Just exactly what was needed here, Chris. Thanks!


Q. I'm busting out some sidewalks due to roots growing underneath them and picking them up and cracking them. Now I hear that copper flashing would detour the roots away from the side walk. Is there any truth to that? Thanks.

john rodgers
consumer - fort pierce, Florida


! Hi everyone.I was searching the internet for ways to solve the root problem in my sewerage system at home - and oh boy am I glad I eventually found a solution. For years I have now on a yearly basis had to have my plumbing cleared out at an expense of about 200 dollars per show! At each occasion I asked the plumber whether there was anything that I might pour in the drain to stop the roots from regrowing, and the resultant answer was always negative. Why should they slaughter the goose that lays the golden egg! They most probably knew about copper sulphate but was not letting a regular like me get away! In any case - thanks a lot for the advise. Regards, David.

David Nel
private - cape town, South Africa


A. We had a lot of expense and problems with overflowing toilets requiring annual sewer cleanouts. One year we called a local RotoRooter franchise and after the $185 cleanout he sold us a product he said would help with the root problem. I think (this was a number of years ago) it was packaged under the RotorRooter name in a 1# canister with instructions on how to use it. The ingredient was copper sulfate. The bad news was it was $20. But it worked. We used it 6 months after the clean out and and twice yearly since and have not had to call a plumber for this problem since.

Later while visiting our county agricultural (farmers) co-op for gardening supplies I ran across copper sulfate on the shelf along with all the insecticides, fungicides, etc. One lb. canister was $9.95. We have used this twice yearly since and have not had any root problem with the sewer line. I know it does not fill up the line, but must seep into the cracks to kill roots entering there. Stands to reason the longer it is there, the better the penetration. So I use it at night before we go to bed so it won't just get washed away by the next flush.

It worked for us. Good luck.

Michel McEwen
- Birmingham, Alabama

May 17, 2008

A. The builder connected to old clay pipes when he ran my sewer lines. I just had my pipes done and all the roots he could get cut out. He has been my plumber for many years and he had recently found out about copper sulfate. He suggested that I use 1 1/2 cups of copper sulfate crystals every other day for 30 days and then once monthly after the first thirty days to keep from having to call and get this done again. He instructed me not to put it down any of my drains but directly in the cleanout outside my house just before bed and then flush to get it to the roots and leave in the pipes the maximum amount of time. I don't know if this will be helpful to anyone but this was not the intended use of what I bought and there were no instructions on the container. I did get it at the farmers co-op.

Sherry Smith
- St. Louis, Missouri


November 25, 2008

A. RootX is not a copper sulfate product.

RootX kills roots on contact; the dead roots decay over time and are carried out with the flow of the pipe, restoring the pipe to its full capacity. RootX also leaves a barrier on the pipe walls to prevent future root growth. Once you've put your pipelines on a maintenance program with annual RootX treatments, you should be able to eliminate mechanical root cutting in most cases.

Walt Holliday
- North Royalton, Ohio

Ed. note: Hi Walt. This site is for technical education, not comment spam. Please provide a link to the MSDS so Mike M and the other visitors seeking technical education site can learn what it is rather than that it's not copper sulphate :-)

March 26, 2009

Q. Can anyone tell me what to use and how much to use to kill tree roots about 30 to 40' away from from my septic tank. There is a hybrid willow tree whose roots are taking over.

Sherrie Pate
- Pelham, Tennessee

July 14, 2009

A. From 30-40 feet away the copper sulfate won't work. Adding it to your septic tank will kill any roots in the tank proper, but not the rest, that's why it's safe for the trees. Be aware that willow trees will spread their roots over 50 feet, several trees may be connected and the only way to get rid of the roots altogether is to kill the trees.

I had some invasive willow growing in my back yard and I was told the best way to kill willows is with products containing Dimethylamine salt (often seen as 2,4-D and sold as broad leaf weed killer like Spectricide weed stop.) It can also kill other trees and plants like roses, dandelions, and clover (but not grass) so you'll need to be careful about application. And yes, it works better than Glyphosate (Round Up or weed and grass killers) on willows, since it gets taken up by leaves and roots where Round Up gets taken up mostly by the leaves.

M A Tullos
- Carson City, Nevada

August 15, 2009

Q. I understand that copper sulphate kills tree roots. I use Rid-x [linked by editor to product info at Amazon] on a regular basis, to increase bacteria. Is there any detrimental effect to bacteria from use of copper sulphate? Thanks.

Jo Coke
- Signal Mountain, Tennessee

June 28, 2010

Q. I've heard that drilling a 2-3" hole down about 8-10 feet over your sewer pipe and pouring copper sulphate down this hole once a year will discourage roots from even thinking about going near your pipes.
Drop a length of ABS or other plastic pipe into the hole and put a threaded cap on it to keep it open for next years application. (Cut it short enough so it doesn't interfere with your lawn mower.)
Sounds like good advice to me, but I can't for the life of me figure out how to drill this hole.
With what?
Haven't need able to find an auger the right size or a way to keep lengthening the drill.
I'm toying with the idea of using black threaded 1" pipe, so I can keep adding lengths to it, but what to use for a cutting head?
Also having trouble locating copper sulphate, everyone I ask advises against using it anyway for environmental reasons.
I can understand this if I was just flushing it down the toilet into the sewer system, but dispersing it into the soil ten feet down sounds like a fairly innocuous way to solve my problem.
I'd rather stop the roots BEFORE they get into the pipes than fight with them afterwards. (been there, done that, expensive)
I'd welcome suggestions.

Rick Lilley
- Burlington, Ontario, Canada

June 18, 2014

A. I have a suggestion for the guy that can't figure out "how to drill an 8 foot hole " in his backyard.
They can rent fencepost hole diggers!
Some are small, like a 2" auger.
I drilled a lot of holes with a 6" auger. There is an attachment that lets you go deeper, and get it stuck if it's clay.

Another way is to make a small one.
I do prospecting, so I needed a simple solution to drill thru the mud to find the rock bed.
parts: 1 large 2" or 2.5" washer,
1 steel rod 1/2" x 4'.
Now, using a hand held hack saw or other metal cutting device,
cut through washer. Inside diameter was either 1/2 or 3/4 in hole--got it cut--ok bend it down about almost 1/2".
Welder: arc works, you can braze weld it if you have the equipment, or pay a welding shop.
It takes less than a minute to zap a weld.
End product: one very simple post hole digger or pipe hole digger.
I used a steel rod i found. Some old car jack handles are 4' long...i used a 3/8 drill, and had to grind the shaft down.
It worked, but i should have had a bigger drill chuck. It ate mine, but i got my hole done!
(8' will wobble, use two 4' pieces); somehow make an attachment to extend the shaft. Some old jack turn handles have such a knuckle -- or have a nut welded on the up top end, and thread the extension.
Or dig down about 3 feet with shovel, and drill rest of way using a 5 or 6' rod. Then install 2.5"" steel fence post or pvc pipe. It's not actually part of the drain system so it could be steel pipe, fence post, 2 inch copper(expensive) or pvc.
Other part is a way to turn shaft: electric drill.
But if you opt to use a long car jack handle, don't cut the turnbuckle off!
You could use 1/2 in black pipe, weld on washer, drill in to ground and forget it!.
Note: new fence post are like this -- I think someone saw my idea. Neighborhood spies!!!
Available at most junkyards!
Or hire a fence guy to drill it for you!
I can't figure out why some of you guys can't figure it out!
Too much time in penny loafers and not construction boots, eh!

- new brunswick, Canada

Ed. note: "No good decision was ever made in a swivel chair" -- George Patton.

August 3, 2010

Q. Where are you Canadians finding the Copper Sulfate? What is the name of the product/brand it's sold under? I've search every hardware/farm supply store around and no one seems to have it except for one place had it in a 40-lb bag which is a lot more than I need.

Patsy Barnhardt
- Chepstow Ontario

March 6, 2011

In Canada you can get the product at the pharmacy, you have to ask for it, it isn't on the shelf.

Ric Mcarthur
- Canada

April 26, 2011

You can get large quantities at any agricultural store or grain elevator store site. Head down (or call first) any villages near where you live where they have such a store. The prices are much-much cheaper than the stuff you get in hardware store, but you will have to buy it in larger quantities.

Navjot Sandhu
- Lansing, Michigan, USA

January 7, 2012

Try getting copper sulfate at a feed mill.

Carl Fischer
- Leo, Indiana, USA

January 27, 2011

Q. My pipes go to a street sewer. How can I "hold in place" the Copper Sulphate to kill the tree Roots that are entering in the drain pipes? I just had Roto Rooter grind out the roots, as they did 3 years ago. Also, should the Copper Sulphate be washed into a sink or flushed in the toilet? and how much? Then would letting it sit overnight for many hours do the job?

Bill Spencer
- Sonoma, California USA

February 1, 2011

A. Just had Mr Rooter channel the main line through two blockages. They also installed a cleanout between the tank and the main line. Have a 30+ year old system. My question concerns copper sulfate and clay pipe. Does the copper sulfate harm clay pipes? The installer explained about copper sulfate and we did pour some in the cleanout and flushed with water.

Terri Martin
- Bulverde Texas USA

Sulfuric Acid
Drain Cleaner

February 27, 2011

A. I have a house built in 1941. It has clay pipes with roots in them. For years we used plumbers' Drano, nearly all the other things mentioned here. about 3 years ago the toilet was backing up into the tub. we plunged used Drano etc. we are seniors and have limited money. We were in Publix grocery store and debating whether or not to call the plumber. I saw a product I'd never seen before. The name is Liquid Lightening. it is virgin sulphuric acid. We used it and it worked. We have not used any other product since. It is about $10 for 32 ounces. It does not say it dissolves roots but anything organic. It has always worked for us.

alan jones
- jacksonville florida united states of america

February 28, 2011

! Hi, Alan.

Thanks for the success story. Be really careful with sulfuric acid -- it dissolves metal pipes as well as other stuff. And never even think about mixing it with any other drain cleaner. Most of the others are strong alkalines, and mixing a strong acid with a strong alkaline is explosively dangerous.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

June 27, 2011

! I just wanted to warn people that if they use Copper Sulfate in their drain field there is a chance that they could kill any trees that are close to the drain field.
I found this out the hard way. My sewer repair person recommended I put 5 pounds of copper sulfate in my drain field once or twice per month after he cleaned the roots out. After one application I now have a giant live oak that is completely dead. Another huge live oak that is looking very unhealthy and a smaller live oak that is showing signs of being sick.
I only gave my sewer system one application because before it was time for the second application my trees were starting to drop leaves and look sick.
Had my sewer repair person warned me that this may happen I would have opted to have the drain field mechanically cleared of roots whenever it needed it rather than have my beautiful oaks killed.

Gary Keenan
retired - Lakeland, Florida, USA

June 27, 2011

Hi, Gary. Thanks for the warning.

However, you might want to talk to your county agricultural extension service and see if someone can confirm this as the cause of the death of your trees. Some knowledgeable horticulturists and floriculturists are quoted in the previously referenced page at
as saying: "Use of this treatment has yet to cause the loss of a tree or shrub".


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

September 4, 2011

As a Chemical Engineer the Copper Sulphate can corrode Iron pipes too fast:
CuSO4.5H2O + Fe = FeSo4 + Cu
The pipe will be washed up by water as FeSo4 ...

Jim Brown
- Milwaukee, Wisconsin, USA

Root Killer

March 5, 2012

I just purchased this product yesterday:

Roebic K-77 =>

The label indicates that it contains 99% copper sulphate and 1% inert ingredients. 2 pounds cost me $18 US. The instructions were to flush the product down the toilet at night before retiring. I hope it works.

Gary Harris
- Santa Fe, New Mexico USA

June 18, 2012

A. I would really question dumping large quantities of copper sulphate down the sewer. It is highly lethal..!! I would strongly advise checking with local authorities before doing it. This stuff can't be removed during the normal process of treating waste water. It could end up back in your drinking water.
Also...putting it in your septic system is just going to kill all the natural organisms and bacteria that have to be there for the septic system to work properly.
Really do your homework on this stuff before you use it.

Dave Little
- Whitby, Ontario, Canada

June 27, 2012

Q. In a post dated July 14 2009 by M A Tullos- Carson City, Nevada an answer was given that copper sulfate will not be effective 30-40 feet out.
My question is: if one flows an large amount of water when applying the CuSO4 will it not be carried to the root site and do an adequate job?
I have a problem with roots approximately 60 feet out, I would appreciate a response and would like to know that this treatment will work.

Tom Peck
- Linton, North Dakota, USA

October 8, 2014



October 2014

A. Hi Dot. It's available on-line everywhere, but you will surely find it locally in a pond store or garden store.


Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

April 17, 2015

Q. My neighbour's maple tree has roots above ground on my lawn. When mowing my lawn it is harming my lawn mower. How do I get rid of these roots?

Gerry S [last name deleted for privacy by Editor]
- Fort Erie, ON. Canada

August 2, 2016

A. Problems with drain fields can be taken care for minimum cost. I use copper sulfate down my leech field once a year. I dig up my drain field at the end of my septic (I never put copper sulfate down my septic). I will open up the drain field and pour half pound down the opening of each outpouring drain and flush with water. Prior to that I will run my hose or long snake down the leech field piping and determine how stopped up it is. I will then take my pressure washer hose without the wand and run it down and blowing all the trash inside away. You may take a light snake and run down the drain to pull out any trash of feeder roots that may have built up in the drain. Then I will flush my copper sulfate down each drain. Takes a a couple hours once a year for this treatment. Trees all around my tank and leech fields. Has never harmed my trees and keeps my drain field flowing. I will do this tomorrow as has been year or so since my last treatment. Good luck.

alan crofoot
- old town, florida usa

September 24, 2016

I am replying to the person who used "5 pounds of copper sulfate" in the drain/line all at once, and a tree died after that treatment. All of my research indicates that five pounds of this noxious chemical is far too much to use; in fact it appears to be about 24 times the recommended dosage. The treatment advice I follow is: "Pour 1/2 cup of crystals into your toilet and repeatedly flush it until all they (sic) are gone. It is better to space the small treatments over a two-week period than to give the roots a single large dose on one day...After you flush copper sulfate down your toilet, leave your house for a day to avoid inhaling any of its fumes."

Barbara Bowden
- Russellville, Arkansas, United States of America

Root Killer

October 29, 2016

Q. I have roots in my downstairs shower. It clogs the shower and toilets and makes it overflow. Can I pour Roebic Foaming Root Killer down my shower drain?

James Klein
- reseda, ca, usa

November 13, 2016

A. Consider other mechanical or low tech solutions rather than copper sulfate. For those of us living near Lake Erie, 2012 had a serious algae bloom and fish kill attributed to agricultural chemicals. Ask yourself if you want to drink this? Lake Erie is our fresh water source.
Read before you make this choice,

Karin Lepp
- Niagara Falls, Canada

November 2016

thumbs up signThanks Karin. The abstract of that second article sounds great!

The world still desperately needs public libraries because you can't get authoritative research without someone paying for it, whereas we also can't really expect members of the public to pay $38 for an article :-)

(Yes, I realize that limited access can be gotten for less than $38, but I'm not talking about the exact licensing terms for one specific article, but rather the general problem of access to authoritative info being costly).


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

April 16, 2017

Q. Hello,

I use mix of water around 90%,copper sulfate pentahydrate - 5% and 35% Sulfuric Acid - 2%. Whole amount of liquid is 20 Oz.
Is it safe to throw it in the drain? Do I hurt pipes, since Im using it to achieve a thin layer of copper on steel? Is it safe for bath tub, and can I paint the steel in bathroom, since I have to water rinse?
Thank you

Z Varga
Metal finishing - Subotica, Serbia

April 2017

Hi Z. In some countries, including the USA, the toxicity of a waste product is only half of the question; the other half is what was the source -- because the laws governing the disposal of waste depend on the source as well as the contents.

From the technical side, though, what you wish to dump is rather dilute, and very close to what is used to kill roots in drain pipes, and the quantity is not a lot -- so it's probably not a big deal to pour it down the toilet (it might stain the bathtub). But a better plan might be to stuff steel wool into your bottle, so the copper will plate out as metal, rather than remain dissolved.

Good luck.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

July 14, 2017

Above link claims that rock salt can be used as well as copper sulfate to kill roots in drain lines. I, myself, have no experience in using chemicals to clear drain lines. Therefore, I cannot comment on the efficacy of these methods. But certainly the rock salt is cheaper and more easily obtained than copper sulfate, albeit still hazardous.

David Biddle
- Cary, North Carolina, USA

December 27, 2017

A. Hello Metal Finishers, My fiance' & I just had our lateral roto-sliced for the first time by a professional for exactly $100, complete. (Not bad, huh?) In the past 6 years, we've rented 3/4 inch-diameter power snakes from (local home supply chain) for $75-(now)$85/day and done it ourselves.

The rental machines do not come with the slicing-type head; standard issue is: one spear, one curly-spring, and one U-shaped 2-inch-wide, chewed-up thing. The method has been to "snag" the clog, and RIP IT OUT by brute force, risking collapsing the clay lateral. This time, I found a plumber who had a single, curved, off-set-blade head, so we hired him. I could see the snake lash-back when he hit the root ball, but it sheared through in less than 60 seconds.

Each time, we've treated with about a cupful per month of "econo" brand CuSO4.5H2O crystals, down the commode and flush just before bed, so it has a chance to mix and distribute as slowly as possible. Things stay running clear as long as I remember to get it and use it. Then I get lax, and 6 months later - well, you-know-what happens.

I always wondered why the root-killer directions said to pour the whole 2 lb canister down the cleanout, just so I could watch my $12-$15 swoosh down underneath the roots, out the sanitary system (city dwellers) and into Lake Michigan. That's why I decided to add a little at a time.

My apologies for length, but here's some facts I found today:

Copper(II) Sulfate Pentahydrate only dissolves at 30 grams/100ml (@40 °F) of water, so the US average flush of 1.6 (ULF) to 3.6 gals (6 to 13.6 L) could dissolve approx 1 to 2.4 lbs (480 to 1080 grams) of crystals, then out to the environment.

Online sources absolutely recommend a foaming treatment or a foaming-additive and the plumber distinctly specified adding it to the commode before bed, so the foam would have ample time to activate, expand, and cover the pipe's entire inner circumference. Any wash-out occurs underneath the roots, and foam still clings to the roots.

More importantly, there's Diquat Dibromide, Metam Sodium (both no longer recommended) and Dichlobenil foaming chemical alternatives, but disallowed in some states and municipalities, and microbial/enzyme choices.

As for drilling 4 to 6 ft deep 1.5 to 2 inch dia holes around the lateral, (IMHO) good luck with that. I've used a 60 inch x 3/4" dia. electrician's bit to start steel posts, but I give the guy who fabricated his own hole-digger a lot of credit.

Here's some links for those interested:

William Gronitz
- Milwaukee, Wisconsin, USA

February 28, 2018

Q. Need help.

I have 2 septic tanks, the one connect to the drain field is filled with roots inside the tank!

Can I pour copper sulfate directly into the tank by opening up the tank concrete cover, will this help to kill the roots and also stop more roots coming into this tank!

Bob Warren
- Gloucester,Virginia

March 3, 2018

A. A septic tank is a small scale sewage plant and depends on the action of anaerobic bacteria. Copper has strong anti-bacterial properties. I would think very carefully before adding copper sulphate to a septic tank. Your nose will soon tell you if the bacteria are dead.

geoff smith
Geoff Smith
Hampshire, England

March 8, 2018

A. Bob,
A quick google search on the matter reveals there are specialty products for killing roots in septic tanks. Also, whoever does your routine septic tank cleaning could probably advise you on the best course of action.

ray kremer
Ray Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
stellar solutions banner

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