There are many causes of pinhole leaks in copper tubing. Some of the most common are: improper reaming when cutting the tubng, excessive flux, agressive water such as water with high DO, CO2, chlorides and sulfate content, acidic low pH water, chlorine, bacteria, and then improper electric ground and/or grounding to copper water lines, dissimilar metals corrosion and hot water recirculation systems etc. and I'm probably forgetting a few.
Call in a water treatment dealer that knows and understands the causes and to do or have a lab do a water analysis to establish causes based on water quality.
Call an electrician in to check the building's ground system and redo any telephone, cable tv etc. grounds.
Gary
Quality Water Associates
