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

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Q. My pipes go to a street sewer. How can I "hold in place" the copper sulphate ⇦this on eBay or Amazon [affil links] 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
January 27, 2011

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! I just wanted to warn people that if they use copper sulphate 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 sulphate 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

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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

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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
March 5, 2012

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Q. In a post dated July 14 2009 by M A Tullos- Carson City, Nevada an answer was given that copper sulphate 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
June 27, 2012

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Q. I AM VERY INTERESTED TO TRY copper sulphate FOR MY DRAIN - WHERE WILL I FIND THIS IN THE GTA AREA? Thanks!

Dot RAMIEN
- TORONTO, ON CANADA
October 8, 2014

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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
April 17, 2015

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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
October 29, 2016

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Q. Hello,

I use mix of water around 90%,copper sulphate 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 16, 2017

A. http://homeguides.sfgate.com/use-rock-salt-tree-root-problems-23203.html
Above link claims that rock salt can be used as well as copper sulphate 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 sulphate, albeit still hazardous.

David Biddle
- Cary, North Carolina, USA
July 14, 2017

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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) sulphate 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:

https://en.wikipedia.org/wiki/Copper(II)_sulphate
http://www.sciencelab.com/msds.php?msdsId=9923597
http://homeguides.sfgate.com/effects-copper-sulphate-root-growth-sewer-lines-82210.html
http://homeguides.sfgate.com/long-root-killer-remove-root-clog-85263.htms

William Gronitz
- Milwaukee, Wisconsin, USA

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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 sulphate 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
February 28, 2018

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Will copper sulphate Damage Clay Drain Pipe?

Q. I just had my clay pipe drain line mechanically cleaned. I have flushed copper sulphate crystals down the toilet for 16 years which kept the line open until now.

Besides going through a notable root +/- 70 feet out, the technician who cleaned the line said that copper sulphate crystals will progressively damage the integrity of the clay pipe with use. Is this true? Specifically how will it damage clay pipe?

I searched but couldn't find much information on the web about this (arousing my suspicion), but still would like some unbiased information based on expert experience.

Rex Stambaugh
Home Owner - Denver, Colorado
December 20, 2018

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January 10, 2019

Q. I found this question and I hope it's ok if I jump in & ask for help.
I'm wondering if I can get some help on using copper sulphate to kill roots in clay home drain piping.
A well-known plumbing company just got my clogged drains flowing but their video shows that roots are still growing in a few places where the pipe sections meet.
All 40 ft of PVC before the clay pipe is intact.
Their tool only bored a 2-1/2" hole thru some roots in the 4" clay pipe due to my 2-story slab foundation house only having a 2-1/2" clean-out in the garage that a tool could fit in. The video showed water flowing under the camera that was only about 1/2" deep.
They wanted to do an expensive Hydro-jet to clean out all of the roots.
Will copper sulphate soak up into roots to kill them if it is just occasionally flowing past the roots that are laying down in that 1/2" of waste water or does the pipe need to be partially plugged so that the copper sulphate touches all of the roots for a while?
Here's a PrintScreen from the video. Can somebody can help me learn what I should do with copper sulphate, which is legal to use where I live.

The drain pipe runs about straight out from where the clean-out is. The guy seems to have zeroed his camera when it went from the PVC into the clay as the DVD suddenly goes from 39' out back to 0'.

Jeff Davis
retired & on disability - Orange, California, USA

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January 15, 2019

Q. Thanks John Lyons. They aren't planning on using it their Hydro-jet to cut thru anything outside of the sewer line but just the roots that have found their way into to splits between sections of the clay pipe.
So, I'm sure their Hydro-jet would clear the entire inside of the pipe of roots perfectly. My only real question is: how much copper sulphate should I use the first time and then how much/how often after that to keep new roots from growing or actually, I'd really prefer to skip their expensive $600 Hydro-jet and just kill what's left of the roots in their now.
From what you know, do you think dropping about 2, 4 or 6 lbs of copper sulphate crystals into the cleanout in the garage one night before bedtime and then flushing the toilet once would let some copper sulphate kill what you see in my photos and it those would just break off and go down into the sewer and then I could add a little maybe monthly at bedtime and let it seep in between the clay pipe's section divisions to kill any new growth it found?

Jeff Davis [returning]
retired - Orange, California, USA

I'm still hoping for help on my simple questions that are in my last reply. Can somebody give me some very basic help on getting started using copper sulphate to kill the rest of the roots in my sewer lines and then to set up a preventative maintenance schedule? Jeff Davis [returning] retired - Orange, California, USA January 19, 2019 January 18, 2019 Jeff Davis My home made water jet was actually in response to some questions about drilling from the surface into the trench that the sewer line was passed in originally. I would really hate for someone to drill into their piping while attempting this with an auger. My treatment plan is to flush 1/4 - 1/8 lb weekly/monthly when the house will be empty for several hours. John Lyons Homeowner - Palisade Colorado USA

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Q. Thanks. That's similar to what I've read elsewhere. But most of them seem to say to use more the first time. One said to dump 2, 4 or 6 lbs in that first time just before bed & just flush the toilet once. I think I could do that pretty easily and if it was that much, I'd think dumping it into the clean-out in the garage would be the easiest way.
I'd like your opinion.
What's been also bothering me is, if the drain line isn't plugged, won't the water and copper sulphate just flow down in the lower 1/3 or 1/4 of that pipe out to the street, so will that even make contact with enough of the roots that I see in that picture I posted are growing in from different angles and not from all at the bottom of the pipe where the water usually flows?
Or do those roots have many little antennas so the ones that look like they're coming down from above are also connected pretty closely to others that are entering down in the sewage and will soak up copper sulphate and be shortened by killing them back a few feet each time I add some?

Jeff Davis
retired - Orange, California, USA
January 22, 2019