electrolysis or not on the supply line?

I am not sure which plumber to believe. One says to not be concerned about the green stuff and the other say’s it is a leak waiting to happen. what say you?

It is moisture from somewhere. Could just be condensation. Any signs of water staining on the cabinet below?

Yes, there was some staining on the cabinet floor. So not electrolysis?

Probably just everyday, ordinary, nothing fancy, MOISTURE! The question is… condensation or an active leak?

Write what you see and know. Period.

PS… the plumber that said “It is a leak *waiting *to happen”… well… it is already happening… where does he think the moisture is coming from? (Other than condensation).

Chemical/cleaning supply storage.

Assuming both supply lines are of the same material and age, this is not likely, as they both would have been affected equally.

Not necessarily. Look at the right side, more room over there, therefore more concentration on that side. I’ve seen situations like this before.

That is the right side of the supply which is the cold water line most likely condensation from cold water in a warm house. I have seen small leaks on lines like that and over time they scab closed but turn the copper green. Nothing to turn back flips over IMO

Charlie is correct. Copper cold water lines will turn dark over time if moisture condenses on them on a regular basis.