Copper Sulfate Septic: Main Root-Killing Ingredient

Copper sulfate septic use is aimed at dissolving roots that have grown into the field lines. Leaks in the system can cause huge headaches for a homeowner. Perhaps even more disturbing is the toilet backing up through the main drain and into the house. When something goes wrong with the system, it is important to get a specialist to help trouble shoot the problem. One of the problems your specialist will want to rule out is tree roots that have invaded the lines between your house and the tank. When you look at a tree in the yard, as a general rule you should assume that the root system below ground is as big as the branches of the tree above ground. That is the primary reason that most septic specialists recommend that only grasses and shallow rooted plants be planted on or near the drain field.

Copper sulfate is a compound created by combining copper with sulfuric acid. It is sometimes called cupric sulfate, blue vitriol, blue copper, bluestone or chalcanthite. Since it is toxic and acidic, care must be used when handling.

Copper Sulfate Septic

The Oklahoma Cooperative Extension Service published a report that says it does work to control tree roots in septic lines. Essentially, when the chemical comes into contact with the roots of the tree, it’s absorbed a short way into the root system. Because of the acidic nature of the chemical, the root is dissolved and carried away as water begins to flow again. The report states that there have been no instances where this treatment has killed a tree or a shrub. The work of the chemical can be slow taking several days to several weeks to actually remove the tree roots.

Many experts recommend against it. The system depends on the presence of bacteria and other microorganisms to break down the wastes coming from the house. Putting a caustic chemical into the system may interfere with the treatment of wastes and may actually contribute to clogging the system. Probably more important from the point of view of your family’s health is that any chemical introduced may end up in the underground water table – and into your drinking water! For this reason, many states and locales have very specific regulations that govern what chemicals can and cannot be used as additives. It is always wise to check local and state codes to verify whether or not it can be used.

Health Risks
Health risks include being extremely toxic to fish and at least somewhat toxic to humans. The Material Safety Data Sheet (MSDS) identifies the following potential health risks:

  • Eye exposure can result in irritation, ulceration and possible corneal burns.

  • Skin exposure can result in an allergic reaction, itching and possible burns.

  • Ingestion can cause nausea, vomiting, jaundice and possible burns in the gastrointestinal tract. Ingestion of large quantities can cause kidney and liver damage.

  • Inhalation can cause respiratory tract irritation and burns.

  • In addition to kidney and liver damage, chronic contact may cause anemia and other blood cell damage. Experiments in animals have resulted in mutations.

  • It has been shown to accumulate in plants and animals.

Proper Use
If you decide to use, be sure to read and strictly follow the manufacturer’s recommendations for application. In general, the recommended amount is two pounds in a 300-gallon tank no more than twice a year. For the first treatment, flush 1/2 cup down the toilet at a time. Much smaller amounts can be flushed two or three times per year for ongoing maintenance against root invasion. Do not put through your sink since it may corrode the metal pipes.

Again, before using in your septic system, you should check with local authorities or the local health department to insure that chemical additives are permitted.

The following recommendations should be considered when dealing with your septic system:

  • Do not plant trees on or around field lines. Because the roots of trees will grow toward any water source, they will eventually cause damage.

  • If trees have been planted near the system, remove them. Prevention is a much better option than dealing with a broken system.

  • Create a root barrier to prevent the problem. Dig a root barrier trench around the septic system and drain field using a trenching machine. When the trench is 18-24 inches deep, insert aluminum flashing into the trench on edge. Fill in the dirt around the flashing and you have created a barrier that will prevent tree roots from invading your system.

  • If you decide to use, follow all instructions and avoid contact with any part of your body. The recommended amounts should be strictly adhered to – this is NOT a case where “if a little is good, a lot is better”!

  • It’s definitely effective at killing roots; however, research has shown that it kills helpful bacteria in the drainfield. So, the risk/reward needs to be considered, and if unsure, seek the help of a professional.

Root Killer with Copper Sulfate

Root Killer Without Copper Sulfate


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