Green deposit on inside half of half inch cold water copper pipe

[Perry]

We had a water leak and the plumber cut out a 3 ft. length of half inch copper pipe (cold water). We cut it longitudinally to see what caused a small tear in the pipe. There were greenish deposits only in one half of the pipe. The other half section where the tear had occurred showed no such colouring. A similar green deposit was also seen on another sample pipe taken from another location. Here again, there were greenish deposits only in one half of the pipe. The other half section where the tear had occurred (marked in the attached photo) showed no such colouring. My questions:

1. Why is the deposit always on one half of the pipe and slways on the half where there is no tear.
2. What are the green deposits (Chemical) and how do they occur?

[Perry]

We had a water leak and the plumber cut out a 3 ft. length of half inch copper pipe (cold water). We cut it longitudinally to see what caused a small tear in the pipe. There were greenish deposits only in one half of the pipe. The other half section where the tear had occurred showed no such colouring. A similar green deposit was also seen on another sample pipe taken from another location. Here again, there were greenish deposits only in one half of the pipe. The other half section where the tear had occurred (marked in the attached photo) showed no such colouring. My questions:

1. Why is the deposit always on one half of the pipe and slways on the half where there is no tear.
2. What are the green deposits (Chemical) and how do they occur?

[Mike_Duffy]

I don't know for sure, but I'd like to ask:

1) Is the tear near a place used as an electrical ground? 2) Were the pipes in physical contact with a different metal (i.e. a bracing strap) close to the break? 3) Were the deposits on the 'up' or 'down' side? 4) Were the deposits near a heat source? (i.e. radiator or heavy current wires, not the water heater itself.) 5) For how long was the interior of the pipe exposed to air before you got around to splitting the pipe to take the picture? Did it have time to dry?

It's difficult to tell how well the colours were reproduced from your camera to my screen, but the colour looks more like algae than cupric ions. On the face of it, this seems very unlikely because blue-green algae should NOT grow in the dark.

Try putting a few drops of powerful acid onto the deposit. (USE SAFETY GLASSES). If it fizzes, it's probably copper carbonate. If it turns black, it's probably organic. Anything else and I would be even more stumped. Is your water very 'hard'? Do you live in Flint, Michigan?

[.]

SHUT THE FUCK UP !!!!!!

[trader_4]

That would be very probative, assuming the pipe is run horizontal.