I came across some corrosion on a copper hot water line in our house:

enter image description here

Is this a potential early warning sign of impending pipe failure?

I did some research online and came across multiple contradicting hear-say-comments ranging from "this is caused by left-over solder flux, it doesn't matter" all the way to "there likely is already a leak and it'll probably get worse quick!".

If this is an issue that warrants pipe replacement, do I need to cut off all of the corrosion (might be a bit difficult in the front pipe as it disappears through a beam) or is it enough to clean it off with some steel wool?

  • I am no expert on plumbing, have just done work around my own house. But were I you would go ahead and replace it now. The pipe in the foreground of the picture has pretty extensive corrosion a fair distance from where solder/flux could have caused it and is on the bottom which is where I have seen pipes corrode/fail most.
    – James
    Commented Jul 29, 2014 at 18:11

1 Answer 1


Clean it off with some wire wool. As far as I can tell, it looks like marking where flux has run and is unlikely to be any serious corrosion that warrants pipe replacement, but the best way to tell will be to clean it off and see the state of the pipe for yourself close up.

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