Black copper cold water lines

[sparksnmore]

I'm sure there are many other things that can cause copper pipes to discolor but one I know about is simply moisture.

A toilet constantly running causes the cold water pipe to be much colder than normal therefore cause it to sweat, especially if a basement window or such is open.
Naturally only the cold side pipes would turn black in that particular case though.

Who knows what chemicals have been previously stored in people's basements or storage areas.

I carry lengths of new copper pipe inside of 4" PVC pipes on top of my service van and after a while pretty much all of them are black from being wet.
If it wasn't so cold out and I wasn't so lazy, I could go out right now and shoot a picture of new copper pipe that is black from carrying it around.

[rwand1]

Doug

Perchance do you have a dirt floor in the basement?

[Jack L. Gilleland]

What type of softener is in the room? Salts of any kind react with copper to speed up the discoloration (whether it is natural or chemically modified). Whether it is Electrolysis or chemical (such as sulfides) the environment is the key to the color.

Copper naturally reacts to its environment and goes through a weathering progression, the rate of which is related to its degree of exposure to moisture, salt and atmospheric pollutants such as sulfur. In some arid climates, it will mature to a nut-brown or ebony-like patina. In coastal or moist areas, the patina will progress to variations of a grayish-bluish-green. Usually, within 10 years to 30 years, copper will reach a weathering equilibrium where the oxide film stabilizes and no longer changes color; however, it continues to protect copper from aggressive corrosion attack.
(From Professional Roofing Magazine)

[rbrady]

When I read about galvanized steel to copper contact, the experts always seem to say that the galvanized steel is the one that will corrode. However that has not been what I have seen. What I see many times is that the copper pipe turns green where it makes a ground connection.

One of my most important rules is - Alway try the easiest things first. (because you will feel like a fool if you tried the hard stuff first and it turns out to be the easiest thing)

Maybe the cold water pipes were colored black to distinguish them from the hot water pipes.

[Vince Santos]

Old post here but I inspected a home yesterday with black copper supply lines throughout the basement. There was a water softener in the basement.

[rmaday]

Originally Posted by vsantos

Old post here.

But, interesting (and informative) post.

Surprised that the chemical theory wasn't dismissed because the OP only had one set of pipes that turned.

Hmmmm...

[James H. Bushart]

To preclude theft, I have seen many homeowners paint the copper black.

[Vince Santos]

Originally Posted by jbushart

To preclude theft, I have seen many homeowners paint the copper black.

haha, now there's something I never thought of. However I have the feeling the typical copper thief would know better than to pass up the apparent gas lines. Last night I inspected a vacant home with copper drain lines. All I could think about was how a scrap thief would be drooling at the sight of it.

[Bob Elliott]

I had this question once.
Noticed when going thru art fairs that certain coppers would turn black ,while others did not.
Never got a total straight ,one fits all,but it may be the metal itself,as I have seen it effect sections,while others kept color.

Personally ,I never comment on it in a report.

[jkogel]

The cold water pipes collect condensation more than the warm pipes.
The water softener might add to the humidity, i don't know.
The other ingredient is dust, which sticks to the wet and forms a black crud layer.
I wouldn't give it much thought beyond that.

John Kogel
www.allsafehome.ca

[rmaday]

Originally Posted by vsantos

Last night I inspected a vacant home with copper drain lines. All I could think about was how a scrap thief would be drooling at the sight of it.

LOL, Had a client a few weeks ago who was very excited to know he had some copper drain lines. He planned on taking out the copper drain lines to pay for some repairs.

[Emmanuel J. Scanlan]

Here is another thread about sulfur off gassing on Chinese made sheetrock that is causing extensive copper damage. One of the symptoms is copper turning black.

http://www.nachi.org/forum/f18/chine...ur-home-35729/

[Jeremy D. Johnson]

I just inspected a condo built in the early 1900's and the home was repiped in with copper lines, all of which have turned black. The crawl space was infested with cat and cat poop. The copper line was bonded with a galvanized clamp and the pipes were sprayed with ammonia. By the way, cat poop is hard on the knees when its a hundred years old.

[Kenneth W. Forrester]

Is the black on the outside of the lines? If so, sounds like an airborne cemical reaction. Perhaps a high concentration of off gasing hydrogen sulfide gases from "chinese" drywall of the earth. From the earth it could be from excessive organic mater under the soil, ie a bog.

[Andrew Shick]

Let me add to the confusion.

I did a house yesterday that was built it 2004 (pre-chinese drywall). It had a recently finished basement, but I could see the back side of a lot of the drywall and it was manufactured in the US.

The water line from where it entered the house at the slab to where it changed over to PEX was almost black. The cold water line going into the WH was dark, but not as dark as the service entrance pipe. The hot water line coming out of the WH looked normal.

Some of the copper bands on the PEX and some of the copper fittings joining the PEX had turned color, but some hadn't.
It can't be electrolysis because the pipe on the WH wasn't in contact with any other metallic pipe or wire or hanger.

It can't be a gas leak, or some other kind of fume or vapor because some of the copper close to the discolored copper looked normal.

The bus bars were discolored with a bit of a patina, just enough to take the shine off of them, but the wiring inside the panel wasn't.

No signs of any moisture in the basement. No odor in the house. No signs of any deterioration of the pipe.

I have no explanation.
I'm gonna write it up as being unusual and let it go at that I guess.
It kinda bugs me though.

Edited to add - Maybe it's a simple explanation, like the plumber had some copper left over from another job that he had been carrying around on his truck (which began to change color), and since they needed so little for this property, he just used what he had.

These pics aren't the greatest, but I think they show it well enough.