: I just installed a new counter and sink. I have a leak where the drain meets the galvanized? drain coming out of the wall. A metal coupling connected the galvanized to the plastic drain/trap. How can I seal the coupling over the galvanized so it won't leak?
The galvanized drain going into the wall has a slight downslope to it, to provide drainage. The tailpiece that you cut to install the plastic drain and trap is either too long or too short. It causes the plastic drianpipe that runs into the galvanized to be on an angle that can't be compensated for by the compression washer inside the metal coupling. You have to really concentrate to get the tailpiece length correct to stop this leak. The kit that you used should have contained a fat and a thin O ring bushing that can slide over the plastic drain and fit into the compression washer metal coupling. The threads are fine, and often are bent by aggressive home repair persons trying to overtighten to stop this very leak. If the threads are stripped, it will forever leak. If the threads are good, either shorten or lenghthen the tail piece to get the straight angle as the plastic enters the galvanized.