On Feb 25, 6:27*pm, Bob wrote:
Hello,

Have had a pinhole leak this year, and also a few years back, so started
looking at my Copper house water plumbing a bit.

Noticed several areas with that bluish-green coating on it.

a. Is this indicative of a pinhole leak developing ?

b. what actually is this bluish-green "stuff" ?

c. *Is it a reaction of the Copper with the outside air, and thus
developing on the pipe's outside, or it coming from the inside ?

d. *Interesting in that I see it in the middle of a run, here and there,
so it's unlikely that it is caused by any soldering flux residual.

I do also see it at joints, and am wondering if it is caused, here, by a
soldering flux residual ?

Any thoughts on the bluish-green stuff, and pinhole leaks would be most
appreciated.

BTW: *how common are pinhole leaks in older (around 35 yr old) homes ?

Thanks,
Bob

The bluish green stuff is predominately copper carbonate and copper
hydroxide. Formed when oxygen , carbon dioxide and copper react.

http://en.wikipedia.org/wiki/Copper_carbonate
http://en.wikipedia.org/wiki/Copper(II)_hydroxide

A lot of the problems arise with copper pipe due to bad manufacturing
techniques. Traces of die metals and lubricants initiate the
corrosion process which is then self sustaining. Also if there is
galvanised iron elsewhere in your system (zinc) you get electrolytic
effects going on.
If the pipe is very thin, holes soon appear.

Some fluxes used in the soldering process have a similar effect.