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

Q. I have huge amount of roots in the pipes. I'm looking for a source of copper sulphate [on eBay or Amazon (adv.)]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 [deceased]
R.I.P. old friend (It is our sad duty to
advise that Freeman passed away 4/21/12)

copper sulphate [on eBay or Amazon (adv.)]50 pounds

(affil links)

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,
Ted Mooney, P.E.
Striving to live Aloha - 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 sulphate 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 sulphate 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,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. I was told to get copper sulphate, 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 sulphate 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 sulphate. 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 sulphate 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

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 sulphate. He suggested that I use 1 1/2 cups of copper sulphate 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
May 17, 2008


(affil links)

A. RootX is not a copper sulphate 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
November 25, 2008

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 :-)

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
March 26, 2009

A. From 30-40 feet away the copper sulphate 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
July 14, 2009

Q. I understand that copper sulphate kills tree roots. I use Rid-x [affil links] 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
August 15, 2009

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.

Q. Where are you Canadians finding the Copper sulphate? 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
August 3, 2010

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

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
April 26, 2011

Try getting copper sulphate at a feed mill.

Carl Fischer
- Leo, Indiana, USA
January 7, 2012

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