Allied Foundation

Sewer Line Replacement

Greater Houston Area

Replace aging cast iron sewer lines that leak under your foundation slab.

Signs to Look For

  • Recurring drain backups
  • Slow drains throughout the home
  • Unexplained moisture under the slab
  • Sewer odor inside or outside the home
  • Home built before 1980 with original cast iron lines
  • Grass staying wet when it has not rained
  • Foundation appearing to sink toward the interior

Project Photos

Under-Slab Sewer Replacement in Progress

Allied worker in a yellow helmet cutting old cast iron pipe with a reciprocating saw
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About This Service

Sewer line replacement in Houston is often tied to aging cast iron pipes under slab foundations. Thousands of homes more than about 45 years old still have original cast iron lines. As those pipes corrode, crack, and leak, water can soften and erode soil under the center of the home, contributing to interior settlement and foundation damage.

Allied Foundation specializes in under-slab sewer line replacement for Greater Houston homes. We use camera inspection to locate leaks and damage, then tunnel under the foundation to replace deteriorated cast iron with modern PVC sized and pitched for positive drainage to the main.

Fixing the sewer problem is dirty, specialized work, and it is often the missing piece when foundation movement keeps returning after other repairs. A free estimate starts with understanding what your drains and slab are telling you.

How Leaking Sewer Lines Damage Foundations

When cast iron fails under a slab, leakage is not just a plumbing inconvenience. Water under the structure can wash out support, create wet spots in the yard when it is not raining, cause backups and odors, and pull the house toward the interior as soil support is lost.

Cosmetic foundation repairs alone will not solve an active under-slab leak. Diagnosing the pipe condition first helps you invest in the right sequence of work.

Camera Inspection and Replacement Process

A free video inspection sends a self-leveling camera through drain lines so technicians can see cracks, offsets, and deterioration in real time. That non-invasive look guides the scope of replacement so work focuses where the pipes actually fail.

We tunnel under the existing foundation, disconnect damaged cast iron, and install new PVC anchored to the slab with proper pitch to the main drain. Extensive sewer replacement work is commonly completed in a focused multi-day window depending on access and scope.

How the Process Works

  1. Step 1

    Video inspection

    Camera diagnostics identify leaks, cracks, and the condition of under-slab lines.

  2. Step 2

    Scope and estimate

    You receive a clear replacement plan based on what the camera found, not guesswork.

  3. Step 3

    Tunnel and replace

    Crews access lines under the slab and replace failed cast iron with properly pitched PVC.

  4. Step 4

    Restore and verify

    Connections are completed, flow is verified, and the work area is cleaned up.

Customer feedback

What customers say

Recent notes from homeowners who worked with Allied on sewer line replacement.

Read more reviews →
Google
Our 60 year old cast iron pipes buried under our house finally gave out and our plumbers told us they needed to tunnel under our house to replace them. But like many plumbers, ours needed to hire a separate company to do the painstaking and expensive hand tunneling work. The bid came in extremely high. We then found Allied Foundation. Their core business is foundation, and they are extremely knowledgeable and reasonable with repiping. And because they have an in-house team of master plumbers, all of the work was bid without any second markup. Most importantly, their estimator took a different approach and rather than tunneling hundreds of feet under the house, they suggested smaller, less intrusive tunnels connecting to new plumbing in less invasive trenches outside the footprint of the structure. Their proposal had three benefits: lower cost, the project could finish in one-fourth the time, and the new pipes now have more places for clean outs which will make any future work easier. We gave Allied Foundation the job. The on-site foreman was hard-working, smart, attentive to our questions, very communicative, and always present. Their entire team were equally hard-working and a pleasure to have in and around our home. The clean up was great. They even quickly followed up on a few items needing tweaking. We would highly recommend Allied Foundation for any complex tunneling/repiping project.

Leanne Coben

Sep 2026

Google
We had Allied Foundation replace our main sewer line, and the whole experience was great. They replaced everything from the slab all the way out to the city tap, around 100 feet, and tied in the laundry line from our garage while they were at it. Part of the run had some tough access under our deck, and they worked through it without issue. Everything was permitted and passed city inspection the very next day.The crew cleaned up well and backfilled the trench, and they're coming back to make sure it all settles level and to tidy up the new cleanouts that were added. Luis was responsive the whole time and easy to reach with any questions. Their pricing was very competitive, and out of the several bids we got, they offered the best scope for the price, with a 3-year warranty on top. Would absolutely recommend them and use them again in the future! Thank you!

Earl Lacey

Aug 2026

Serving Greater Houston

Allied Foundation Repair serves homeowners across Harris, Fort Bend, Galveston, Montgomery, Brazoria, Chambers, and Liberty Counties. Explore local pages for soil notes and neighborhoods we know well, or request a free evaluation for your address.

Frequently Asked Questions

Common signs include cracks in walls or brick, doors and windows that stick, gaps around window frames, uneven floors, and drainage issues near the foundation. Not every crack means major damage. An evaluation helps determine whether movement is active.

What's Happening With Your Foundation?

Request a free evaluation from a family-owned Houston team with over 75,000 homes repaired. No pressure, just clear answers.

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