You’re in a *gracefully mature* slab home with cast iron drain lines. So far, you’ve had some drain line backups and maybe had to replace a failing portion of the drain pipe. You (or your plumber) suspect that the drain lines under your home are rusting and perhaps near the end of their life. What. To. Do?
At Anchor Foundation Repair, we’ve helped hundreds of Brazos Valley homeowners deal with replacing cast iron drain lines using under-slab tunneling. We understand what a hassle, headache, and expense this can be. I’ve even lived through it in my personal home!
This article will discuss the general symptoms you might see when drain lines are rusting out under your home, how to maximize their use, and your options when it’s time for their replacement. By the end of this article, you will feel more prepared for the process and cost associated with under-slab drain line repiping.
How Long Do Cast Iron Drain Lines Last?
It seems like cast iron would last forever, but alas, it does not. Especially in an underground setting, the moisture and soil contact, not to mention chemical exposures, eventually rust out drain lines and cause them to fail. Just how long can you expect cast iron drain lines to last then?
Industry and online data is somewhat scarce and inconclusive, but it looks to be near 50 to 75 years when cast iron begins to compromise and fail. So if you’ve got a home built in the 70s or earlier with cast iron lines, this situation might be coming down the *pipeline* soon if it’s not already upon you.
In the Brazos Valley community, I guesstimate that the number of cast iron re-piping jobs has increased by 15% or so in the last 10 years. I don’t have hard numbers, but I have solid observations that this is happening based on an increase in the work we do with under-slab tunneling and conversations with local plumbing professionals.
Can I Extend the Life of Rusting Cast Iron Lines?
I’m sure your first thought is, “How can I prevent this from happening or delay the need for a full replacement of cast iron lines?
Please understand, you likely cannot prevent rusted-out drain lines from happening altogether. It’s more like delaying the inevitable for as long as you can.
If your home is on the *younger side* of the timeframes we’re talking about or you haven’t had too many issues yet, there is one thing you can *try* to stave off cast iron drain line deterioration. It’s to stop using such harsh chemicals for cleaning plumbing fixtures.
When they put in cast iron lines, they really probably thought they would last forever. That was before they started inventing all these super-caustic-magic-cleaning-and-unclogging formulas for your home.
We found this fairly impartial article that gives product recommendations and suggestions: 5 Best Drain Cleaners for Cast Iron Pipes. Check it out for more in-depth info. Please note that we get *zero dollars* for suggesting the article. We just found one that seemed to have an unbiased approach.
What Symptoms Mean That Drain Lines Are Starting to Fail?
Here are the kinds of things to pay attention to that indicate your cast iron drain lines might be failing due to corrosion:
- Slow-draining fixtures,
- Repeated drain line backups requiring plumber visits,
- Portions of drain line have already been cut out and replaced,
- Gurgling fixtures,
- Strong smells that come and go, or
- Signs of foundation settlement near leaking plumbing fixtures.
These symptoms are not only for rusting cast iron drain lines but really apply to any type of compromised drain line. We’ve got a whole article with details on under-slab plumbing issues for you to peruse.
Options to Repair or Replace Cast Iron Drain Line Systems
You’ve got a few options for repairing and replacing cast iron drain lines ordered from least to most proactive:
- Reduce harsh chemical cleaners and cross your fingers,
- Wait until backups happen and replace piecemeal sections of the drain line system,
- Do as-needed repairs with access gained by breaking through the slab or tunneling,
- Sleeving and pipe-bursting methods can be used in some cases,
- Replace everything at once with under-slab tunneling.
Options 1, 2, and 3: Preventative and As Need Approaches
You might already be beyond the point where reducing harsh chemicals will work, but you can certainly *roll the dice* and try. Being less proactive costs less upfront and at one time, but it also means potentially prolonging the process. You will deal with more backups, more plumber visits, and more headaches at inopportune times.
If you’re doing smaller repairs as problems occur, you do have a choice of handling some issues via breaking through the slab or by under-slab tunneling. Either way, you end up with a patchwork drain line made from multiple materials with more connection (i.e. potential failure) points as opposed to continuous new piping.
It’s very important for under-slab plumbing to be repaired properly to prevent further problems from occurring.
Though more expensive, tunneling is the only option for certain under-slab problems. In other words, you can’t break through the slab and fix every type of issue. Tunneling also offers the bonus of being able to live in your home mostly undisturbed while repairs are underway.
Check out this article for a full comparison of breaking through the slab vs. tunneling for more thoughts on this matter.
Option 4: Sleeving and Pipe-Bursting (maybe)
Sleeving and pipe-bursting are specialized non-invasive methods meaning they prevent a lot of digging trenches and holes. These methods will work on straight runs and yard lines, but won’t allow for branches and smaller pipe connections under your home.
These methods might not be readily available or available for residential applications in your area. So these may or may not even be viable options depending on where you live.
Option 5: Full Replacement Using Tunneling
A full re-piping of the entire drain line system is a massive project, but you do get the whole thing done once and for all. All the cast iron will be gone and replaced with modern PVC. You have a fresh new system that shouldn’t have issues for a long time to come.
Using tunneling allows you to remain in the home and also keeps your slab intact.
Sometimes it’s better to *bite the bullet* and do these larger, more proactive projects just to get them over with and handled for good. That’s what I ultimately decided to do on my 1970 slab foundation home.
The Cost and Timeline To Replace Your Cast Iron Drain Lines
For a full cast iron drain line conversion to PVC using tunneling, it would take about 3 to 4 weeks to complete the process. The estimated cost of under-slab tunneling for about 62 linear feet of under-slab plumbing access is around 25K or more. Plus, the cost from the plumber for replacing the lines.
The upside to under-slab tunneling is that your plumbing bill should be lower because the tunnels make it easy for them to access all the repair locations. Also, as mentioned before, tunneling allows you to remain in your home undisturbed during much of the repair process.
Yes, this is a high-priced major project. The cost is comparable to any other major home systems repair like a new roof, new electrical system, or even a full kitchen remodel. But for someone who loves their home and doesn’t want to worry about their under-slab plumbing or deal with repeated drain line backups, it might be worth it.
Insurance May Help Cover Certain Costs
If you have leaking lines under your home that need to be reached by tunneling, homeowner’s insurance can sometimes cover the cost of tunneling if it’s part of your policy. Insurance is worth checking into for help in paying for this part of the repair. Though, the actual plumbing work is not likely to be covered.
Want To Know More About Under-Slab Tunneling?
Now that you know about some of your options in dealing with degrading cast iron drain lines, is tunneling starting to sound good to you or maybe you want to know more about it?
At Anchor Foundation Repair, we offer under-slab tunneling as one of our primary services for homeowners in Bryan, College Station, and surrounding Brazos Valley communities like Brenham and Navasota. We are the only contractor in our area that specializes in under-slab tunneling and finishes the job with mud-pumping for extra support of the backfill.
Check out, “How Does Under-Slab Tunneling Work? Basic 5 Step Process,” for more information on how this work is actually done on your home.