How to use copper sulfate to kill roots

Written by michael davidson
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How to use copper sulfate to kill roots
Copper sulphate is usually found in blue crystal form. (Comstock Images/Comstock/Getty Images)

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.

Skill level:

Things you need

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

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  1. 1

    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.

  2. 2

    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.

  3. 3

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

  4. 4

    Repeat this procedure every six months or as needed.

Tips and warnings

  • 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.

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