Copper Pipe Corrosion Pinholes

When we moved into this house, I noticed a hose clamp around the half-inch copper pipe carrying hard water to the toilets and kitchen sink:

Hose clamp patch on copper pipe

Hose clamp patch on copper pipe

That’s obviously a whole bunch easier than removing and replacing a section of copper pipe, so I’d say it was entirely justified. The fact that it hasn’t leaked for at least the last quarter century counts for something.

However, Mary recently discovered a small wet spot on the basement floor. Looking directly upward, we saw:

Copper pipe corrosion pinhole - 1

Copper pipe corrosion pinhole – 1

That was in open air; I added the marks around the corrosion to highlight it.

I’d applied some foam insulation on the supply end of the pipe and, just to check, peeled it back:

Copper pipe corrosion pinhole - 2

Copper pipe corrosion pinhole – 2

Huh. Although that leak was slow enough to not leak out of the insulation (the slit was upward), disturbing the corrosion produced a regular drip. Again, those marks are new.

OK, two active pinhole leaks and a small dry green spot further downstream says it’s finally time to replace that pipe. The lengths of pipe with the pinholes add up to about eight feet, which suggests the plumber installed a bad piece of pipe back in 1955.

Yes, I applied two more hose clamps for the holiday season, but that can’t last.

Having a good stock of tees, elbows, and unions on hand, all I need is 21 feet (not 20, alas) of shiny new copper pipe to replace the entire run containing all the pinholes; I’m not going to fiddle around replacing just a few sections.


  1. #1 by RL on 2015-12-26 - 10:43

    The causes of pin hole leaks are not well understood, and not necessarily due to defects in the copper pipe. A new section of pipe may develop leaks, too. PEX is your friend!

    • #2 by Ed on 2015-12-26 - 11:05

      A new section of pipe may develop leaks, too.

      A combination of aluminum, chlorine, and high pH might have something to do with it: the well didn’t have much chlorine, but we switched to town water some years ago. Maybe that one section of pipe had a few tiny defects and the “new” water ate right through them?

      Although it may seem short-sighted, I’m hoping to pass the problem to the next administration: I am not splurging on PEX tooling!

      • #3 by RL on 2015-12-26 - 11:52

        I am not splurging on PEX tooling!

        As I said in my other post, Shark Bite fittings need no special tools. They simply slide on the end of the pipe, and the same fitting works with copper or PEX. No solder. No crimping. No glue. My grandmother could do plumbing with these!

  2. #4 by Red County Pete on 2015-12-26 - 10:49

    If you use Home Desperate for the supplier, you might be in luck. Our local store carries copper pipe in two wall-thickness grades in 10′ lengths, but also shorter (2′ I think) lengths. Not sure of the grade, though.

    We’re contemplating a new well (the current one is shared among 3 families) and cross-linked PEX feed line is the new standard, but just catching on here. (Non-trivial investment in specialized tools is slowing adoption.) If I ever did a major replumbing job (not in this lifetime, I swear), I’d consider it for house piping.

    • #5 by RL on 2015-12-26 - 11:08

      For almost tool-free plumbing, take a look at Shark Bite fittings. It takes some getting used to the idea that a slide-on fitting will be reliable and won’t leak. But they work! The downside is that at some point, the higher cost of the fittings makes up for the cost of tools. But damn, they’re easy to work with. Time saved has to be worth something.