I was renovating my house and have to open up the ceiling. Once the ceiling was opened up I see that our copper water piping has some green residue only on the joints. I was doing some research online and seem that the conclusion is mixed, some say not to concern while other think that it needs to be fixed.

There is one or two drops of water on the joint where there is green. Do I need to worry and replace the pipe with PEX and copper fittings? If I were to do something now is the time as the ceiling is open up. I have attached a picture for reference.

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  • Are your pipes on the living side of your ceiling or in the attic itself? Do they extend into the attic?
    – Machavity
    Dec 22, 2016 at 22:26

5 Answers 5


The connection is leaking. What more do you need?

There is water on the outside of the pipe. It has been leaking for possibly decades and evaporating as quickly as it leaks. The moisture, along with the solder and possibly flux, has corroded the outside of the pipe, leaving the characteristic green-blue color of dissolved copper.

More importantly, the leakage flow is verrry gradually eroding the sides of the small opening. The opening is growing, the flow is growing, and eventually, it will start dripping and then pouring on everything below...

I've seen this in a pinhole leak in a copper 90 degree elbow. The elbow had been installed for at least 30 years in the ceiling over the entrance hall. The first visible symptom was water dripping from the ceiling light fixture. When we opened the ceiling, there was an extremely fine mist coming from the pinhole. All the nails and screws in the joist space were rusted out...


Somewhere in the past there was a lazy or ignorant plumber - they presumably used an acid flux when soldering, and they failed to remove/clean the excess from the pipes after the joints were soldered. It's been quietly corroding ever since.

If it's reached the point of leaking, you definitely have a problem, though droplets of water on pipes CAN be caused by things other than a leak, such as condensation if the water in the pipe is cold and the air around it is humid. but in that case the droplets would normally be all along the pipe.


Not only should you replace this because it’s leaking, you should replace it because it’s an absolute Frankenstein of a connection and is bound to fail at some point or another.

The photo isn’t clear, but it looks like at the metal strap there isn’t a 45° fitting but the “plumber” soldered a piece of soft copper tubing inside a copper pipe without any sort of coupling.

If this is the case, even if it was soldered perfectly, the flow of the water is hitting the edge of the piping and becoming turbulent (assuming the water is flowing right to left), increasing the wear on the soft copper pipe, which may be what’s causing the corrosion further along the pipe.

Even if that’s not the case, the fact there is a leak at the metal strap is further hastening the corrosion due to the fact that those straps are usually only copper plated steel and the copper plating adjacent to the corrosion is long gone by now. With dissimilar metals adjacent to each other and a little drop of “electrolyte” (particularly if you have hard water or a water softener) you’re getting ion exchange and it’s only a matter of time before they both corrode away.

By the way that blue color is a mix of all the copper salts from reacting with what’s in the water, copper chloride, hydroxide, fluoride (if the city adds fluoride to the water) and oxides. All of them are removing copper, ion by ion from your pipe and making it weaker!

Don’t wait, fix it while you have the wall open!


Drops of water on copper plumbing are not acceptable. At the very least there are pinhole leaks developing and the sections with that must be replaced.

We had 10 to 20 pinhole leaks in the middle of a vertical run of 1/2" copper from the hot water heater. The water ran down and soaked the carpet in the back of a walk-in closet. This resulted in the loss of some valuable items. The cause of these pinhole leaks is in dispute and the phenomenon may have multiple causes.

In your case it is not clear whether these are leaks from failing sweated joints or are the failure of the copper itself. If I were you I would replace the green sections with copper, but when using rigid copper tubing be sure to avoid the thinnest wall (Type M) and use the thicker wall Type L (maybe use thick wall type K if that is used for water pipes). Soft copper tubing may all be thick wall or there may be different wall thicknesses available. All of the different types in a given nominal size have the same OD so they all fit into the same sweat fittings.


Lighting traveling through the ground and exiting through the roof can create pinholes, especially in concrete foundations. As you've likely learned in school lighting travels from the earth to the sky, or from one cloud to another. These pinholes are Too expensive to find and repair. New plumbing should be installed through the ceiling. Happens quite often in Florida in older homes.

  • Hello, and welcome to Home Improvement. It's surprising that lightning could cause pinhole leaks; what's your basis for this? Apr 18, 2019 at 22:01

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