Hello,

Live in a 35 year old house outside of Boston.

Had a leak in a Copper water pipe that the plumber finally found.

Unfortunately, I forgot to ask him if it was in a hot or cold line, as this
might, perhaps, be meaningful ?

Anyway, what surprised me was that it was pinhole leak in the middle of a
run.
Not at a joint or fitting, etc. Right in the middle of a line.

Apparently they used the thinnest Copper they could find when they built the
place.
I used a caliper on it, and found it to be 0.028, which I guess is a grade M
(outside diameter of 5/8 inch)

But, it still should take the household pressure without any problem, I
would think.
True ?

The plumber replaced it with heavier wall stuff of approx. 0.038, which is
probably
Type L

Questions:

a. What might make a pinhole leake in the middle of a clear run ?
I guess the pinhole can be considered as a corrosion type of breakthrough.

b. How common is something like this is the thinwall Type M tubing ?
What causes ?

c. 35 years ago, was this (Type M) a common Copper gage they used for
household
hot and cold water lines ?

d. Is it still allowed, or the Code prohibits it now all over ?

Any thoughts on this would be most appreciated.

Thanks,
Bob.