Creating new Plumbing vs. Replacing

[Joseph Nguyen]

I have a duplex where the entire cast iron plumbing is essentially running its course and has a few cracks in it in various places due to frequent foundation repairs/shifting and tree roots growing into the pipes. The issues are throughout the entire home (slow drainage in furthest toilet, water backing up in kitchen / when using Washer and Dryer, etc). I believe the cracks throughout are leading to more foundation issues since it's a slab foundation and the leaking under the property is disrupting the soil underneath.

I've gotten a few quotes on replacing the entire system under the home (most ranging 40-70k), but had another quote for creating a completely new PVC plumbing system AROUND the property instead of underneath and completely abandoning the current Cast Iron plumbing underneath the house. The latter option was significantly cheaper and makes sense to me (would also be less disruption to foundation since minimal tunneling under the foundation).

I was wondering if anybody else has done something like this and you experience? Thank you!

[Bob Ritner]

I have 2 duplexes that had the same issue. All of the plumbing was on one side of the buildings so we ran a new ABS lateral in the side yard and ran new abs branch lines from each fixture to the lateral in the side yard. We did this as a part of larger property renovations so we were not trying to save flooring, cabinets, etc. The actual plumbing, slab cut and patch was about 12k for each of the duplexes, but if you are not doing this as a part of a interior renovation, the related demolition and replacement of cabinets, finishes and fixtures it would add thousands more.