I replaced some plumbing about a month ago and it has already pitted where it goes through the floor. The previous pipes were here for years without pitting.
IT maybe that you didnt wipe the flux off the pipe? what type of floor? if it is cement then it is the lyme that corrodes copper. also after using flux and solder the quicker you can run water thru it the better the job flux is an acid and will eat the copper from the inside out
