There are many times when metal is better than plastic.  Unfortunately, if you have cast iron drains, this is not one of those times.  While it is true, pvc has made it impossible for us younger plumbers to ever be as manly as the plumbers of the past, it has also made the life expectancy of today’s drain systems much longer.  I guess in a way, the much lighter pvc has also made the life expectancy of the plumber a little longer as well, or at the very least saved our backs a little.  Above are some photos of a job we were on today.  The image on the far left is the reason we were called out.  The cast iron completely rotted away and had a nice size crack running up it as well.  The picture in the middle is the cobbled mess of materials we took out and replaced with pvc.  This house had cast iron, stainless steel running off the top for the vent, pvc for the bathtub that was recently renovated and copper for the sink drain. The picture below is what it now looks like.  If you have cast iron in your house, it WILL eventually go bad and rot/rust away.  Depending on the setup of your house, this could be a relatively easy job or it could be a very involved venture.  Ranch style homes with the drains exclusively in the basement are generally pretty easy to replace.  Two story homes with a bathroom on the second floor and cast iron going up a wall will test the plumbers patience, and the homeowners wallet every time.  Deteriorating cast iron drains present a two-fold problem.  The first and most obvious problem will be the leak, and we aren’t talking spring water!  The other problem is the sewer gas that will be consistently making it’s way into your home like an uninvited guest.  Sewer gas can be anywhere from unnoticeable, to annoying, to deadly.   Don’t live with leaking sewage or smelly gas, it’s only going to get worse.  By replacing the cast iron, you will avoid recurring costs for drain cleaning, and you will avoid a pretty nasty mess down the road.  Remember, it’s not IF it is going to leak, it’s WHEN.  This is one of those times when a little preventative maintenance is a good thing.  An ounce of prevention is worth a pound of cure.