The plumber will tell you that the CPVC is as durable as copper and will aalst as long, but in my area, CPVC is used for domestic fire sprinkler lines while copper is used for the domestic water. The fire sprinkler lines have a history of breaking which is not true of the copper ones. In addition, the CPVC has the same outside diameter as the copper, but because the pipe itself is thicker, the opening in the pipe is much smaller for any given pipe size. For this reason, the CPVC should be installed with all lines one size larger than the corresponding copper size. It is my opinion that there has not been a good piece of plastic made yet.: I live int the wash dc area and am getting ready : to have a plumber do a re-plumb job. should i choose : copper or cpvc? why?