I'm renovating my bathroom. I ripped out the floor and I noticed that there is a green deposit on the outside of the copper tubing. Is this a problem? Do I need to have a plumber check it out? The pipes are 50 yrs. old.enter image description here

2 Answers 2


The green deposit forms as the copper of the tubing chemically combines with other elements on the nearby environment. The presence of wetness or water can accelerate the formation of the greenish copper compound.

I have seen multiple instances where the acidity of the water sitting and flowing inside the pipe can eat the pipe walls thin from the inside over many years. This can lead to pin hole leaks in the pipe that lets small droplets of water come out and produce corrosion of the pipe like seen here. It would be well worth checking out this area of the copper pipe to see if there is a pending disaster waiting to happen.

  • I'm definitely concerned about pinhole leaks. I have acidic water. It would be really sucky to re-do the bathroom and then have a pinhole leak.
    – Laxmidi
    Dec 19, 2015 at 22:35
  • I had a set of pinhole leaks like this in piping above my water heater.
    – Michael Karas
    Dec 19, 2015 at 22:55
  • I decided not to risk it and will replace the pipes.
    – Laxmidi
    Dec 30, 2015 at 17:28

That normally means there was a water leak at some point. If you look at the pipe on the left in your picture, you can see a small trail coming down from up above. Is there any sign of water above the floor/cabinet? A small amount of green on copper usually isn't anything to worry about. You just want to make sure that whatever is leaking has stopped.

If there is still a leak, clearly you'll need to fix that.

  • That's an interesting observation. I hadn't noticed the trail. There was a small amount of deteriorated drywall near the sink. It looks like the previous owner had a leak at some point. I don't see any leaks now.
    – Laxmidi
    Dec 19, 2015 at 22:33
  • I have seen the green copper many times with no problems. I have seen a few where there was moisture, possibly a over flow made the Sheetrock wet and some corrosion has started. If no leaks clean the pipes and spray with a lacquer clear spray paint. If it stays clean , no problem,,, more green says there is a leak or small pinhole , cannot jump to what it is with just 1 check
    – Ed Beal
    Dec 19, 2015 at 23:02
  • Ed, I hadn't heard of the lacquer trick before, but that's neat. I'll have to remember that.
    – thatguy
    Dec 19, 2015 at 23:20

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