Updated January 18, 2024
A common job that professional plumbers perform is leak detection. Pipes inside a house can start to lose water through corrosion damage, and once the homeowner has realized there’s a problem (usually because of a rise in water bills) it takes skilled plumbers to locate where the leak is occurring.
You might expect old pipes made from outdated materials such as iron and galvanized steel to eventually develop rust and other types of corrosion. But copper, the most common metal used for modern plumbing, is supposed to be corrosion-resistant. Why would a copper pipe start to leak?
Corrosion‑resistant is not corrosion‑proof
Watches that are advertised as “water-resistant” won’t suffer damage if they get some water on them, such as rain. But that isn’t the same thing as a “waterproof” watch, which a person could wear when they go swimming. The same “-resistant” and “-proof” difference applies to copper. It resists most forms of corrosion, but not all. Copper is more likely to last than iron or steel, but corrosion can still affect them.
Formicary corrosion, the enemy of copper pipes
The specific type of corrosion that can create leaks in copper pipes is called formicary corrosion, from the Latin word for “ant,” Formica, and sometimes called “ant’s nest corrosion.” This corrosion appears as a grayish patch on copper piping where the metal has weakened. It will soon lead to pinhole leaks, which are difficult to detect at first but will become major problems in plumbing.
The causes of formicary corrosion are not yet fully understood, but it appears that its connection to organic acids in the water supply or the home’s air that are difficult to eliminate. Corrosion is more likely to appear in humid climates when there is a greater amount of water in the air to react with the other components.
Regardless of how this corrosion starts, you need to leak repaired (which usually involves replacing the pipe) as soon as possible. Call professional plumbers to handle this.
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