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Copper Pipe Crisis

Recently, copper pipe, which is widely used in plumbing systems, has been the target of many complaints regarding unexpected and premature deterioration, often leading to leaks.

There are those who point to some changes in water quality regulations in the early 1990s as the cause. One theory suggests that the higher-quality water no longer encourages the development of a thin, protective film (patina) on the inside of the pipe and that without that film, the pipe is more vulnerable to corrosion. That seems to be a simple explanation, perhaps too simple. To check that theory, we consulted with experienced people in the public water industry. This is what we found out.

First, as suspected, that theory oversimplifies what is a very complex subject, and one that is not fully understood. The premature deterioration appears to have many causes that are site-specific, often related to installation conditions, chemistry and bacteriology.

It is true that many water utilities have improved their water by adding chemicals to reduce lead and copper corrosion. That has demonstrably lowered levels of both contaminants in public water supplies. It is not clear, however, whether those changes have had any direct effect on the deterioration of copper piping.

Everyone seems to agree that corrosion in copper piping appears to be escalating. From all available evidence, the causes are diverse. High levels of chlorine and stagnant water are two causes of copper corrosion that can work together to accelerate deterioration. Stagnant water with low oxygen and high bacterial content is known to cause copper corrosion. And inactive plumbing systems are vulnerable.

Also, for complete disinfection, it has become much more common to super chlorinate new water mains and new copper service pipes at the time of installation. However, if the high levels of chlorine stay stagnant in copper plumbing because they are not immediately flushed and put into service, then the chlorine sets up an ongoing corrosive reaction that is very difficult to eliminate.

Similarly, stagnant water in plumbing in new and old buildings can develop corrosion cells due to bacterial action. This has been noted especially in copper lines feeding water coolers and icemakers on refrigerators that may get very little use during certain seasons. Blue or black water in ice cubes is a symptom of this problem.

Another cause for copper pipe deterioration is electrolysis, which typically affects pipes buried underground. Depending on soil conditions and proximity to electrical power lines, very small electrical current can flow through the pipes. As it does, the current gradually carries the copper in the pipe away and pinhole leaks develop. As the leaks saturate the ground around the pipe, the electrolysis accelerates, as does the loss of copper in the pipe.

Some copper erosion is caused by galvanic action (which occurs when dissimilar metals, copper and steel, for example, are joined directly).

Further, during installation, over-fluxing (using a chemical that loosens the oxides from the metal) the joints prior to soldering or using the wrong flux can initiate a corrosion cell near the joint. Because of the acidic nature of flux, it must be promptly flushed away by putting the pipe into service.

So clearly, there are many reasons for copper deterioration. Much technical writing and ongoing research in the United States and the United Kingdom are devoted to understanding the many causes of copper corrosion. In time, these issues will surely be resolved.

In the meantime, what is the solution? Determining the cause comes first. That process should include contacting your local water utility; they may already have some diagnostics and recommended corrective actions.

Once the cause is determined, the solution may be localized and simple. For a widespread problem, replacing the pipe may be necessary. However, that can be quite costly and disruptive. Lining the pipe is an alternative. There are companies that have developed the technology to line pipes as small as

1/2 inch in diameter with epoxy. One such company is Ace Duraflow. For more information, visit their Web site at You should, of course, thoroughly investigate the problem and get more than one opinion before deciding on corrective action, especially if some of the recommendations are from companies that would benefit from your decision. In new construction, choosing nonmetallic pipe for your plumbing system may be wise.

Criterium Engineers, Copyright ©2006