I see this type of corrosion on water pipes a lot. I usually write it up as possible pinhole leak and investigate/repair as necessary by a plumber. I touched the area and felt no water. Should I just let this stuff go or write it up every time? Thanks.
I’d write it up every time myself…
From the picture it appears an amateur surely did the soldering. Excessive flux will cause discoloration as well as a leak.
I concur with Dale.
Green build-up… The Plumber failed to wipe off the flux when soldering the pipes together.
If it were a pinhole leak, it’ll be a white crusty salty substance built-up around the leak.
This is just sloppy work. Sadly, I’ve seen this kind of work from seasoned professional also.
I agree with David, who concurred with Dale, and I don’t write it up.
I would like to think that a guy* trying* to be a plumber would have left it like that and not a plumber.