are these green dots pinhole leaks waiting to happen?

Question

Recently I had a pinhole leak in my copper 3/4" hot water line. A plumber replaced that section of pipe but today I decided to examine the whole length of the line. I found some corroded copper pipe hangers at various points on the line, but also in some places I found some isolated greenish dots.

Here are pics that show two of them. My question is, are these spots places that will eventually turn into pinhole leaks? My original pinhole leak was at a spot where there was no green dot.

P.S. This is city water, not well water, so I don't think that acid water is eating the pipes.

Answer 1

That looks like a developing pinhole leak. We once had 20 or so in a vertical run of the hot water output line of a gas water heater. These had progressed and water droplets were rolling down the tubing probably for years. Presumably pinholes start on the inside and progress to the outside.

I still have the copper line that was cut out. There were projecting encrustations on the inside of the tubing.

Before cutting out any pipe you could use emery cloth or other abrasive on that area. This should reveal a pinhole if there is one and be conpletely harmless if there is not one.

If it is a pinhole, this could cause an increased leak rate so perhaps you should have some repair supplies on hand when you do this or do this when the plumbing supplies are open.

Answer 2

The spots do indicate oxidation is occurring.

It looks as if something had splashed and the dots are where the substance landed on the pipe. There is a good chance it will evolve into a leak.

I would replace the entire pipe and try to examine as much of the pipe as I can.