Rusting copper supply pipe

Anyone have an idea why this copper supply pipe would be rusting in this isolated spot? Any ideas? Thanks


It looks like copper hangars holding the pipe but I bet there are steel nails making contact under the pipe, holding the 2x4 to the floor joist.

Or those really arent copper but are galvanized from the electrical section. Can’t really tell.

Looks like the corrosion is happening where the pipe is in contact with the 2x4. There may be a chemical leaching from the wood that reacts with the copper.

Jim King

I’ll go with the nails.

Unless the hangars in this spot are not copper?

There seems to be a pin hole leak at circled point. Then water (in its effort to find lowest point) ran down the pipe. What ever caused it (might be electrolysis) don’t know for sure (nail sounds good). This needs to be sanded and soldered at least.
The moisture escaping is small now, but just wait.:wink:
Copper Leak close.JPG

Copper Leak close.JPG

Corrosion appears to be galvanic corrosion. This condition may result in eventual leaking and these connections should be corrected or monitored for future leakage.

[FONT=Verdana]Galvanic corrosion seems to be more active on the hot side of potable water lines. Any metal material will eventually degrade. One can not put a time line on when it will start or if it even will. Just because there is a connection with two dissimilar metals, it does not always mean one or the other will be degraded. Just copper itself, depending on the water, may develop problems[/FONT]

I have found that if there is galvanized steel to copper anywhere on the system, the copper pipe will corrode at the area where the copper pipe is grounded. Between the contact with the 2x4 and the copper straps, it might constitute a (poor) ground connection.