Pinpoint Leaks and Copper Pipe Corrosion

George Mastovich asks,

Can you tell the difference between the type of corrosion that will cause pinpoint leaks in copper pipes and the corrosion that might result from the pipe being in a damp location such as a basement? I have small spots of corrosion (blue-green).

Our Answer

Copper doesn't rust, so it can be in a damp location for decades and not corrode.

Pin holes in copper are usually caused by acidity in the water, and tiny amounts of water leak out and dry. The blue-green spots you're seeing are mineral deposits from that water. The mineral deposits stay behind and form a sort of scab on the pipe.