# Cast Iron Sewer Replacement in San Diego, Slab to Street

> Replacing corroded cast iron sewer pipe in San Diego, under the slab and out to the street: scale, channeling, when lining is viable and when the pipe must go.

URL: https://sandiegoswiftsewerlinerepair.com/cast-iron-sewer-replacement/

Service

Replacing or rehabilitating corroded cast iron drain and sewer pipe, from the building drain under the slab to the lateral in the yard.

[(619) 377-9626](tel:+16193779626)

Last Updated: November 10, 2026

Your older house keeps clogging even after the line is cleaned, there’s a sewer smell indoors, or a scope shows a rough, rusty pipe with a trough worn in the bottom. Cast iron sewer pipe replacement in San Diego can cover two different pipes: the building drain under the house, which may run beneath a slab, and the lateral that carries waste from the foundation to the City main. Cast iron was a standard choice for both in older homes, and it fails in a characteristic way, from the inside out. [San Diego Swift Sewer Line Repair](https://sandiegoswiftsewerlinerepair.com/) replaces and rehabilitates cast iron drain and sewer lines across the City and nearby San Diego County.

The useful question is not whether your pipe is old but how much wall it has left. A camera run after descaling shows us that, and it decides whether a run can be lined, needs a section replaced, or has to come out end to end.

## Why does cast iron fail?

Cast iron is strong and quiet, which is why it was used inside houses, but it is iron, and it corrodes. The City’s lateral fact sheet lists cast iron with clay and concrete among the older lateral materials that may have deteriorated sections and need regular inspection or more frequent cleaning.

Corrosion works on the inside of the pipe in two places. Above the waterline, moist sewer gas attacks the upper wall and builds rust and scale. Along the bottom, constant flow and the grit it carries abrade the wall as it corrodes. Soil chemistry and moisture can attack the outside too, so a pipe can thin from both faces.

The result is a pipe that looks solid from outside and fails inside. Our guide to [what sewer pipe your house has](https://sandiegoswiftsewerlinerepair.com/guide/what-sewer-pipe-does-my-house-have/) shows how cast iron compares with clay, fiber and plastic on camera.

## What the camera finds inside cast iron

**Scale and tuberculation.** Rust builds up as hard, lumpy growths on the inner wall, called tubercles. They narrow the bore and give paper and grease something to catch on. A cast iron line that clogs again soon after cleaning is often a scaled line rather than a blocked one. A cable may punch a hole through the buildup without clearing it; our descaling tools grind it back to the wall.

**Channeling.** Along the invert, the bottom of the pipe where water always runs, corrosion and abrasion wear a groove. Early channeling is a rough trough. Advanced channeling becomes a slot open to the soil below, and on a building drain under a slab that means wastewater leaking under the house and soil washing into the pipe. The top half of the pipe may look nearly intact on camera while the bottom is gone.

**Cracks.** Thinned walls crack, often lengthwise along the pipe. A longitudinal crack in cast iron usually marks a badly weakened wall.

## Is the bad pipe under your slab?

In a house built on a concrete slab, the building drain runs beneath the floor, and in older slab homes that pipe can be cast iron. Problems there show up as backups in lower fixtures, sewer odor inside, damp flooring or a line that won’t stay clear. One painful version: a line jetted during escrow, a short close with no second scope, and backups soon after move-in that traced to eroded cast iron under newly installed cabinets. A [home-buyer sewer inspection](https://sandiegoswiftsewerlinerepair.com/home-buyer-sewer-inspection/) that looks back toward the house is the protection against that.

You have four ways to deal with failing pipe under a slab:

1. **Descale and line** from a cleanout, where the wall is intact enough to carry a liner.
2. **Replace through the floor**, cutting a trench in the slab along the run, laying new pipe at grade and patching the floor.
3. **Tunnel under the slab** from outside, leaving floors and finishes alone. Depth and soil decide whether this is sensible, and it is excavation work with real collapse risk.
4. **Reroute**, abandoning the old under-slab run and bringing new drains out by a different path.

We choose by what sits on top: a tiled kitchen with new cabinets argues for lining or tunneling; an unfinished garage floor makes cutting the slab simple.

## Can your cast iron be lined?

Lining is attractive for cast iron because it avoids cutting floors. The process matters more than the product. We descale the pipe back to the wall, film the line again, and only then decide. A liner forms against the host pipe and relies on it for shape. It can bridge small pits and minor channeling in many systems, but where the bottom has rotted through to soil, pieces are missing, or the pipe has cracked along its length, we open and replace those sections before the rest can be lined. Lining also keeps the pipe’s existing slope, so any sag stays.

Our [sewer pipe lining](https://sandiegoswiftsewerlinerepair.com/sewer-pipe-lining/) page explains the method, and [trenchless sewer repair](https://sandiegoswiftsewerlinerepair.com/trenchless-sewer-repair/) explains where it fits among the other no-dig options. A line that is too far gone for a liner is a replacement job, covered on our [sewer line replacement](https://sandiegoswiftsewerlinerepair.com/sewer-line-replacement/) page.

## Replacing cast iron in the yard and under the street

Outside the foundation, we replace a cast iron lateral much like any other: by trench, by [pipe bursting](https://sandiegoswiftsewerlinerepair.com/pipe-bursting/) where the path is usable, or by lining where the pipe allows. New pipe is usually PVC, joined to any remaining cast iron with listed transition couplings. In the City, you are responsible for the lateral to its connection at the main, so a cast iron section under the sidewalk or street is yours to fix, with a right-of-way permit. City projects have replaced cast iron and clay mains in neighborhoods such as La Jolla, but those are public mains, not private laterals.

## Permits, apartment buildings and cost

For single-family and duplex homes, the City’s Simple No-Plan plumbing permit covers repair or replacement of drains and sewer piping on non-historic properties. Older apartment buildings with cast iron stacks and building drains are larger jobs with their own scheduling for residents; our [commercial sewer line repair](https://sandiegoswiftsewerlinerepair.com/commercial-sewer-line-repair/) page covers that work.

Cost follows access more than material. Our typical ranges are $80 to $250 a foot for lining, $60 to $200 a foot for pipe bursting and $50 to $250 a foot for trench replacement, before permits and restoration; under-slab work adds floor cutting and patching. Your final price comes from a written quote after we see the job, and our [replacement cost guide](https://sandiegoswiftsewerlinerepair.com/guide/sewer-line-replacement-cost/) explains the ranges by method. When you have footage or an address, get an estimate.

## What the work includes

- A camera inspection of the building drain and lateral, both directions where possible
- A locate of under-slab and yard runs, with depth
- A scope separating pipe inside the footprint from the lateral outside it
- Descaling ahead of any lining, with a camera check after
- Replacement in PVC or ABS, or lining where the host pipe allows
- Listed transition couplings at every change of material
- The City plumbing permit and the inspections it requires
- A final camera run through the finished line

## Ways to deal with failing cast iron

| Option | Descale and line | Replace through the slab | Tunnel under the slab | Reroute outside |
| --- | --- | --- | --- | --- |
| Fits when | Walls are intact enough to hold a liner | Pipe is cracked, holed or channeled through | Floors and finishes must stay untouched | The old path is poor and a new route is available |
| Disturbance inside | Little, access at cleanouts | Floor cut along the run | Access pit outside, little inside | New connections at the fixtures |
| Watch for | Holes and missing bottom the liner can't bridge | Finished flooring and cabinets over the line | Depth and soil conditions under the house | Slope over the longer run |

## Related resources

- Learn [What Sewer Pipe Does My House Have?](https://sandiegoswiftsewerlinerepair.com/guide/what-sewer-pipe-does-my-house-have/)Six materials turn up in San Diego laterals. Each one has a look on camera, a typical way of failing and a short list of repairs that suit it. House age narrows the guess; the camera settles it.
- Learn [How Long Does a Sewer Line Last?](https://sandiegoswiftsewerlinerepair.com/guide/how-long-does-a-sewer-line-last/)Age is a clue, not a verdict. What wears out each kind of lateral pipe, what San Diego's ground and trees add, and what keeps a line working longer.
- Cost Guide [How Much Does Sewer Line Replacement Cost in San Diego?](https://sandiegoswiftsewerlinerepair.com/guide/sewer-line-replacement-cost/)Ranges by method, the City's own fees for the street, and what moves a San Diego lateral job from the low end to the high end.
- Learn [How Long Does Sewer Line Replacement Take?](https://sandiegoswiftsewerlinerepair.com/guide/how-long-does-sewer-line-replacement-take/)The digging is rarely what decides the calendar. Permits, inspections, the street and the ground water under it do, and each one is a step you can ask about up front.
- Decision Guide [Does Homeowners Insurance Cover Sewer Line Repair?](https://sandiegoswiftsewerlinerepair.com/guide/does-homeowners-insurance-cover-sewer-line-repair/)The pipe, the damage inside and the City's main are three separate questions. Here is how each one is usually handled, and what to look for in your own policy.

## How we run a job, house to main

1. At the houseFirst call We ask what is happening, where the cleanout is, whether the house still drains and whether anyone has scoped the line before.
2. CleanoutCamera and locate We run the camera from the cleanout, measure every defect and mark the line's path and depth on the surface.
3. YardMethod and permit You get a written scope that names the method, the permits the job needs and a price that lists any street work separately.
4. Property line to streetThe repair Lining, bursting or excavation, and where the permit requires it, the trench is inspected before we backfill.
5. At the mainFinal footage We run the camera through the finished line and restore the yard, sidewalk or street to the standard the permit sets.

## What this work looks like

Cut end of an old cast iron sewer pipe showing heavy rust scale narrowing the inside, lying on a tarp

Cut end of an old 4 inch cast iron sewer pipe held in a gloved hand, thick rust scale narrowing the opening

Section of old cast iron pipe with a no-hub stainless steel band coupling joining it to new black ABS pipe, seen in a crawlspace lit by a work light

Rusted cast iron sewer pipe running under a raised floor in a crawlspace beside the foundation, lit cleanly by a work light

## Cast iron sewer replacement questions

### Can old cast iron sewer pipe be lined instead of replaced?

Sometimes. After descaling, a liner can rehabilitate cast iron whose wall is still continuous enough to hold the liner's shape. Sections where the bottom has rotted through, the pipe has cracked lengthwise or pieces are missing have to be opened and replaced first. We decide from the camera run after descaling.

### What is channeling in a cast iron sewer pipe?

It is erosion along the bottom of the pipe, where wastewater runs constantly. Over decades, corrosion and abrasion wear a trough into the lowest part of the wall while the top can still look sound. Advanced channeling leaves a slot open to the soil, which catches debris and lets water out.

### Is pipe under the slab part of my sewer lateral?

Not technically. Pipe under the house is the building drain; the lateral, or building sewer, begins outside the foundation. In the City of San Diego the owner is responsible for both, and both are private plumbing under the City's plumbing permit, but the methods, access and costs for each part differ.

### Why does my cast iron line keep clogging even after it was cleaned?

Scale and tuberculation narrow the pipe and roughen its wall, so paper and grease catch again soon after cleaning. A cable may punch a hole through the buildup without removing it. We descale the line and run the camera after, which shows how much pipe wall is left under the scale.

## Related services

### Sewer line replacement

A new lateral from the house to the City main, by open trench or pipe bursting, with the permits, inspections and street work that come with it.

### Sewer pipe lining

A cured-in-place liner that forms a new pipe wall inside a cracked or root-prone lateral, for pipes that are still continuous and round.

### Sewer camera inspection

A recorded video of the lateral from the cleanout to the main, with each defect measured by distance and the line's path and depth marked on the ground.