Do you perchance use well water? Or is it municipal? My parents had an issue with their copper pipes within 10 years of building their house. The sheet rock in my sisters' bathroom started to crumble. (yes, that's plural possessive on purpose.) Turns out that their water supply from the well outside was slightly acidic. Acidic enough to leech the copper from the inside of the pipes. This was most evident where threading was done to the ends of the pipes to attach the shower heads. They had to redo the ends only and added a massive filtration system to the entire house.

Another side effect that was noticed is that the greenish tint that was present in all the showers, sinks, and tubs went away. Obviously, our pipes were being deposited regularly in our sinks.