I am in the process of remodeling the main bath. I have cast iron mains and it appears to be galvanized steel for the 2 inch lines. In the past I have had slow drains in both the sink and tub and have resorted to both snaking and chemical cleaners. I have the opportunity to replace the galvanized lines with PVC or ABS, but I don't really want to spend the effort if not required. Perhaps you can help by responding to a few questions?

Background:
Home built in 1962 using Cast Iron for all 3 and 4 inch lines. All the vents and smaller lines appear to be galanized steel with perhaps a few cast iron fittings mixed within the system.

Total length from the bathroom to the main stack is about 20 feet of piping through two 90 degree elbows and a Y fitting (plus the vanity tub connections).

How long should a complete snaking of the system last to clear the lines? The last time I rented a snake was a couple of years ago and the lines were slowing again before the remodel (last 6 months).

Did I perhaps not snake the system far enough to clear all blockages ? Is this likely, seeing as they worked fine and the buildup reappeard so quickly. A few months ago I removed the draing from under the vanity to clean the section of line going into the wall which was 3/4 blocked.

Is it worth the expense and effort to replace with PVC/ABS at this time? The galvanized lines are not leaking and do not appear to have excessive rust buildup.

If replacing is recommended, is there any difference to be concerned of regarding ABS or PVC? I have used PVC in the past and the big box stores carry both ABS and PVC. I would leave the galvanized vents and case iron mains in place and simply replace the trunk lines if I have to.

Thanks in advance,

Rudy

BOY.. you have invited lots of opinions... *laugh*... Now you will have to sort out all the replies!!

OK... my opinion.. I would definetely replace all galvanized pipe under the floor... will only have future issues with anything to do with galvanized pipes under the floor. If you have any galvanized vents... well you do not necessarily have to replace or repipe those... they are not full of crud and basically only transport rain/snow/air so if an inspector will allow it I would not replace those (I would transition over to pvc pipe about 4 feet of the floor using mission type transition clamps.. at least should not have to go into attic with pvc).

AND you now know my opinion on pipe type--->>> I am a huge fan of pvc pipe and fittings... cuts easier by sawzall... not as brittle as abs... and pvc pipe cuts do not melt and have to be deburred nearly as much as abs pipe. Just my opinion, of course.

OK... can't say how long a snaking should last.. BUT I can say that this is the time to replace those crudded up pipes with pvc pipe... goes pretty darn quick once you get in there and start piping away.

So.. as a minimum, at least replace all galvanized waste lines to pvc (I would replace all.. but I am a plumber ;) )

Hope this helps. If so, please rate the answer by clicking on button below. Thank you!

The coeffificient of friction is going to get worse with galvanized pipe over time and that makes stuff stick and not slide easily. The galvanized is no compatible with some drain cleaners, but your not using them anyway? Right?

If the PVC is in reach, replace it. Vents. No, but you may have to add supports for the galvanized vents.

I have used the chemical cleaners available at the big box, but these all typically say safe for all pipes. I got in the habit of using drano once a month to try to keep the lines moving well, but that didn't help my vanity pipes too much, the chrome was starting to fail.

Just a follow-up to anyone else out there. I ended up removing all the galvanized pipe to the stack. The interior of the pipe was almost completely blocked throughout except for a pencil diameter thickness. I am going with all PVC and increasing the diameter from 1.5 inch to 2 inch pipe.

Just a follow-up to anyone else out there. I ended up removing all the galvanized pipe to the stack. The interior of the pipe was almost completely blocked throughout except for a pencil diameter thickness. I am going with all PVC and increasing the diameter from 1.5 inch to 2 inch pipe.
Great posts from Mark and KISS. You were smart to replace with PVC when you could and smarter yet to increase to 2". Good luck, Tom

Thanks for the update Rudy!!

Glad you replaced when you did... imagine if you hadn't!!

Thanks again... Mark