Hole in Copper Water Pipe

This article is about a small hole in copper water pipe. A small hole in copper water pipe is often referred to as a pin hole leak. More information concerning holes in copper water pipe is available in the book  OnlinePlumbingAdvice.com.

A pin hole in copper water pipe

Usually, a pin hole in copper water pipe creates a leak that is a small drip, a small squirt that looks like a cobweb, or anything in between. These small holes in copper water pipe can be difficult to locate and monitor.

When a pinhole leak occurs in copper water pipe, most people become very concerned. People, hope to avoid future leaks, want to know why the leak occurred, and want to know the best course of action. When my customers ask for my opinions about these concerns, I try to answer their questions as clearly as is reasonably possible. After I examine a pin hole leak, I can make an educated guess as to why it occurred.

Damage from a nail or screw is usually easy to determine. The nail or screw is usually obvious. If you have to have a pin hole leak, this is probably the best one to have. It should be the easiest to avoid and the least likely to become a reoccurring problem.

A poorly made solder joint is usually easy to determine. I always cut out the whole joint. When solder fails to fill the inside of the joint, or if the pipe isn’t properly inserted in the joint, the result is a poorly made solder joint.

Improperly cleaning, fitting, fluxing, applying the solder, and/or heating of the joint usually results in this problem.

It is possible that a plumber’s helper or apprentice caused one or two poorly made solder joints, sometimes complications and future problems will not develop. Poorly made solder joints can be a big problem if lots of joints were poorly made. Some concerns about poorly made solder joints include:

  1.  Other solder joints were probably made by the same person that made the joint being replaced. Additional poorly made solder joints could start leaking at any time.
  2.  Solder joints in the immediate area will have to be disturbed to replace the leaky one. Correcting one leak could easily result in more leaks.
  3. Poorly made solder joints can blow apart and result in a major flood at any time.
  4.  Often, poorly made solder joints look fine (what is important is what is inside the fitting).

It seems that most people with a poorly made solder joint leak do not have reoccurring problems. If it looks like a plumber did the soldering, I usually recommend replacing only the joints that leak. If it looks like someone other than a plumber did the soldering, I usually recommend replacing all easily accessible solder joints. Hindsight is always twenty/twenty, so it is important to realize that predicting the outcome is not an exact science, there is no way to know the best course of action every time. (If the plumber is right 99 percent of the time, it is guaranteed that he will be wrong 1 percent of the time.) If an honest, qualified plumber makes an educated guess or presents the available options, so you can decide how much pipe work to replace, you shouldn’t blame him if things go terribly wrong.

Electrolysis of water pipe

Sometimes, it is easy to determine that the copper pipe was electrolyzed (decomposed by the direct action of an electric current). Most plumbers realize that dissimilar metals that touch can create a damaging electrical current (AKA electrolysis), and because of this, it is necessary to protect copper water pipe (or galvanized water pipe) from coming in contact with dissimilar metal. This extremely low electric current produced from dissimilar metals should not be confused with the dangers of electrical current flow from the electric power in the home. I have concerns about a different danger from possible electric power in the home.

I have a theory that since many homes use the copper water pipe as a ground, it is even more important to make sure the copper water pipe does not come in contact with duct work, gas pipe, or other possible metal objects that could interrupt the proper electrical (grounding) flow. I have seen pinholes where copper pipe touches ducts. I worry about copper water pipe touching metal gas pipe.

If dissimilar metal straps or any other dissimilar material is the most likely cause of a leak (this is usually visible when the leak is located) something should be done to correct the problem. Even before problems occur, copper water pipes should be protected from all other metal. Often, thinking ahead and using common sense can prevent dangerous situations from causing problems.

Mysterious leaks

Pin hole leaks in copper pipe that seem to have developed for no reason are becoming a major problem in some areas. Some of the reasons seem to be:

  1. Chemicals in municipal water attack the copper. Typically, most of the pipe will look fine. White or green spots will be visible. The pipe will be stable enough to easily cut.
  2.  Aggressive well water. Aggressive well water often results in paper-thin copper pipe. Fixing one area often requires extensive replacement as pipes are very fragile. [Note: CPVC pipe is usually the best replacement, since CPVC seems to hold up much better under aggressive water conditions.]
  3. Aggressive flux that was used when the pipes were soldered might cause pin holes. When using the aggressive type flux, pipes and fittings do not require as much cleaning before soldering. Aggressive flux used to be the standard for copper waste and vent pipes. Most good plumbers never used it for water pipe. Some plumbers used it on water pipe to save time. I am beginning to think there is a good possibility that what I call aggressive flux is a frequent cause for pinholes. Aggressive type flux results in lots of green stains on copper pipe while non-aggressive flux causes very little green. [Tip: Aggressive flux on your skin will cause an irritating burning sensation, non-aggressive flux normally will not.] If aggressive type flux was used and not carefully wiped off, it is easy to tell by the large amount of green stains. If it is carefully wiped off, it is very difficult to tell. When I see the inside of pipes that have mysterious pinhole leaks, I often find a small glob of green material.
  4. Copper electroplated straps frequently have very sharp edges. Sometimes I find pin hole leaks where the sharp edge of an electroplated strap touches copper pipe. I suspect that the sharp edge eventually cuts into the pipe, or the edge exposes enough steel (the core of copper electroplated straps is steel) to allow electrolysis to create a hole.

[Note: I have never noticed a solid copper strap creating a leak.]

I suspect that there is no simple answer for the increased frequency of mysterious pinhole leaks. I think aggressive flux, applying too much flux, not properly flushing out water pipes, chemicals in the water, ageing of the pipes, and any combinations of these factors play a key roll in this problem.

Future holes in water pipe or not?

After a pin hole leak is fixed, it is not possible to know when, where or if additional leaks will occur. Usually, I cut out as much stained pipe in the immediate area as I think is reasonably practical. Sometimes I replace a large amount of pipe, and sometimes, I cut directly over the pinhole and install a coupling (this usually requires the least amount of expense and the least amount of disturbance to the pipes). Whenever reasonably possible, I try to explain options to the customers so they can decide what they want me to do. Lots of time and money can be spent in one area only to notice additional leaks in the next area. Disturbing defects can cause leaks; sometimes the more work performed, the more risk is involved. The only way a customer should expect the plumber to guarantee no more leaks from the water pipe is if he replaces all the pipes.

Research and customer communication can help provide the best chance for the most cost effective solution. The more information the customer can gather, the better.

Some of the factors to research include:

•    The number of homes in the same development that have had reoccurring leaks.
•    The number of reoccurring leaks in the customer’s home.
•    What information is available from the local water supplier?
•    The number of homes in the same development that had all the water pipes replaced.
•    The age of the pipes.
•     The projected time before major renovation of the home is expected.
•    When does the owner expect to sell the home?
•    The financial ability of the customer.

In most cases, customers should only expect the plumber to fix the immediate problem. The more pipes are disturbed, the greater the possibility of creating additional leaks. Plumbers have a very difficult time figuring how many customers they can help in one day. There is no way to know how long each job will take. Customers should realize that sometimes scheduling at least one additional visit might be necessary. Usually the initial visit is intended to help the customer get the water back on or get a leak under control.

The book OnlinePlumbingAdvice.com provides unique, trustworthy advice that will help you make smart plumbing decisions.


About the Author


Mike started his plumbing apprenticeship in 1969. He has over forty years experience solving plumbing problems in homes. Mike helps people avoid mistakes. He is the founder and president of Quick Quality Plumbing Inc.. Mike published a book (OnlinePlumbingAdvice.com) and he is the administrator for the web site (OnlinePlumbingAdvice.com.)