Hello, My home was built in the early 70's and the sewer drains are 4" cast iron pipe. We have never had a backup of any type with our sewer system. At this time I am having a bathroom installed in the basement (shower, toilet, vanity) using PVC pipe. I was lucky enough that all that was needed to attach new system to old was to undo a no hub connector and add new PVC system. Upon separating old system I noticed that the inside of cast iron pipe was somewhat reduced in size (rust and gunk). A plumber friend told me that this is normal and I shouldn't worry about it. Just want a second opinion about this and if there was anything that can or should be done to insure a problem free system. Thanks for any input. metalmark

While it's true that cast iron will rust in time It will probably outlast you. Short of replacing the cast iron with plastic,( with the exception of relining a sewer pipe to the street) there isn't much you're going to do to "renew" cast iron drainage. Regards, Tom

Cast iron will rot. The gunk you saw in there is rotting your pipe. It is a buildup and cast iron is a porous. This is why you 'grease' a cast iron frying pan. Look for 'rust spots' on the bottom of the pipe. This is where the pipe has rotted and become very thin and the rust spot is actually where the liquid has penetrated the pipe. It may have moisture on the rust spot. In many cases you can actually push you finger through the pipe by simply squeezing it. Also, in many cases when the pipe is in this condition, running a cable through it will break the bottom out. Makes an awful mess.