Pinhole leak in Copper pipe
I was in my basement today, and noticed a small puddle on the floor. I noticed a small leak in the half inch copper supply pipe to the second floor bathroom. This pipe is not in an area subject to abuse.
So, my questions: What would cause a pinhole size leak in a 15 year old pipe?
Should I be concerned about other pipes behind sheetrock? Note: I have well water, and the water is "hard". Would this cause corrosion?
Should I replace as much of this with Type K? (I'm assuming the builder used Type L)