why pinhole leaks in copper?

Old 04-04-03, 01:44 PM
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why pinhole leaks in copper?

I've been getting a number of pin hole leaks in my copper pipes,
only in the vertical supply feeds to the second floor, nowhere else.
I checked the copper and they are the blue labeled ones (L?)

I would think that if I had acidic water I would have leaks throughout my house.

someone suggested that I might have a ground wire attached to my copper pipes, so I installed a 10' ground rod attached w/8gauge wire to the supply line from the street inside my basement. Only to get another leak in 6mths.

what could be causing these pinholes?
Old 04-04-03, 02:24 PM
Mike Swearingen's Avatar
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Acidic water and electrolysis are two very good reasons that copper pipes develop pin holes.
Type L is medium copper pipe, if that is what you have. Type M is lightweight.
If it is allowed by code there, you might try replacing the bad lines with CPVC plastic. Acidic water and electrolysis will not affect CPVC like copper.
Good Luck!

Last edited by Mike Swearingen; 04-05-03 at 06:09 AM.
Old 04-05-03, 06:50 AM
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Copper will develop pinholes over time due to the reaction with the water as OldGuy said, but as for why it happened first on the vertical lines, it is hard to say, but you can bet that if it is happening there now, it will happen everywhere before too long... One reason is probably due to the way the copper is soldered... Horizontal runs are easier to solder without running the flux down the pipe... Vertical runs usually end up with a good deal more flux residue on the outside of the pipe... If the flux is not wiped off, it does the same thing to the outside that the water does to the inside and would effectively give the vertical runs a head start on wearing out... Do the CPVC thing as you are able if you don't want to deal with this problem again...

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