How to use copper sulfate to kill roots

Updated February 21, 2017

Copper sulphate is created during a chemical reaction between copper oxide and sulphuric acid. It is a salt compound that is used in a number of different substances that range from bleaches to dog food. The material can be lethal to plants when applied correctly, and as a result, copper sulphate is sometimes used to kill off roots that are invading a plumbing system. It should be used carefully to avoid damaging the plumbing system, but it can successfully kill invading roots over time.

Pour 110 g (1/2 cup) of copper sulphate into a toilet and flush the crystals to introduce the substance into the sewer pipes where tree roots could be invading.

Add additional copper sulphate into the toilet in 110 g (1/2 cup) increments until an entire 0.907 kg (2 lb) bag has been emptied.

Leave your home for a day afterward so you are not affected by any resulting fumes from the copper sulphate.

Repeat this procedure every six months or as needed.


Copper sulphate works well in septic systems as well and should not disrupt the bacteria balance in the septic tank. It could take several weeks before the copper sulphate completely kills the invading root.


Do not pour copper sulphate down a sink since those pipes are normally weaker and can be corroded.

Things You'll Need

  • 0.907 kg (2 lb) bag copper sulphate
  • Measuring cup
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About the Author

Michael Davidson started writing screenplays in 2003 and has had a screenplay professionally produced. He has also studied martial arts since 1990 and has worked as a licensed security specialist. Davidson has written articles for various websites. He is a graduate of Michigan State University and holds a Bachelor of Arts in advertising.