Pitting: What It Is And How It Affects Your Copper Plumbing System

Have you heard of copper pitting? This is one form of copper corrosion that is greatly feared by those who use copper plumbing pipes. The good news is that it takes time, so it is more of a problem in old houses than relatively new ones.

What It Is

Pitting occurs when the interior surfaces of copper pipes are attacked by corrosive chemicals. Such attacks are usually localized, non-uniform, narrow and deep. Pitting is classified into three types depending on the cause. The three types are:

  • Type 1 – caused by hard water and results in deep, but narrow pits on the surface of the pipe
  • Type 2 – caused by soft water, especially in relatively warm temperatures; results in very narrow pits
  • Type 3 – caused by soft, cold water; results in wide, but shallow pits


Pitting often results in pinhole leaks, which can be very costly. For example, the leaks are minute and not easy to spot, so the effort needed to locate them is not small. Apart from that, they will also waste water and increase your utility bill. Don't forget that undetected leaks can easily lead to further damages such as mold growth and corrosion of fixtures or structures of the house. In fact, your insurance company may even raise your premiums if you frequently complain of water leaks.


Seeing as how pitting can be destructive and costly, it would be ideal if there were a perfect way to prevent it. Unfortunately, this is not the case since it is mostly caused by the chemicals in the water as well as prevailing temperature, things that you may not have control over.

That being said, there are steps you can take to reduce your risks of having to deal with the problem by:

  • Having licensed plumbing contractors inspect any property you wish to purchase for signs of pitting.
  • Ensuring that water does not stay stagnant in your plumbing pipes for long. For example, you can have somebody open the taps regularly if you are away. The more water stands in a pipe, the more likely it is to cause pitting.
  • Avoiding properties that have been vacant for long; such houses tend to have pitting issues.
  • Having your water regularly tested and informing your local water department if it is acidic.

If pitting has already occurred, then you have no option but to hire a plumber to handle the necessary repairs. The plumber will know what to do; for example, he or she may find the leaks and replace the damaged pipes. In worst case scenarios, you may even have to replace your entire plumbing system.