The photo below is something seen a lot when inspecting older homes. This is an old galvanized system of drain pipe that is now beyond its useful life. You can see the moisture around the threads and there was water on the vapor barrier -- a conducive condition. Whenever such pipes are seen, one has to look closely for leaks because any such pipes are old systems and that, alone, means they are suspect. Galvanized drains pipes, especially the horizontal runs, will often leak. Sometimes it is not even apparent at a glance at the pipe. At my own home, years back, I removed such a pipe from the kitchen sink, about a 15 foot run, and when I got it outside in the sunlight it was full of tiny pin holes and rust, lots and lots of rust. This is common with these old pipes. Cast iron pipe is in use in many older sewer systems and stacks as well. So far, it is my experience that the locations where cast iron is used seem to be holding up better than the galvanized runs.
Steven L. Smith
Bellingham WA. home inspector
