A. Dooley...thank you for insulting the chemistry discipline. As it can be best that assumptions is all we have at this point. Chemistry is quite complex and there are many variable that we can ascertain from. It is not my intention to provide any misleading information.
I can just merely speculate as to the chemistry involved, redox reaction, improper grounding and yes, there are plenty of homes with copper lines that do not have this issue. Yet, not all homes have copper water lines...I have seen plastic lines being used in new home construction. So I can can BS in your statement that "every house in America has copper pipes." Given the limited information, my guess would be acidic conditions, perhaps a redox reaction due to improper grounding or the city water really messed up.
Chlorine or other chemical causing this? An excess of chlorine will be quite noticable with a strong smell, unlikely there will be a color change. As for other chemicals, I am wondering if you really understand water chemistry?
