# Sewer line problems in Houston: cast iron, tree roots and what a camera inspection tells you

Source: https://thehoustonhomeowner.com/guides/sewer-line-problems-houston
Publisher: The Houston Homeowner (https://thehoustonhomeowner.com)
Published: 2026-10-05

> Houston sewer lines fail for three main reasons: cast iron drains in houses built before about 1975 that rust from the inside, bellies where the clay soil has let the pipe sag under the slab, and tree roots that find any joint. Repeated backups, gurgling, slow drains in more than one fixture or a sewage smell are reasons for a camera inspection, and no one should quote a repair under the slab without one.

## Why Houston sewer lines fail

**Cast iron.** Houses built before about 1975 usually have cast iron drain lines under the slab. Cast iron rusts from the inside. The bottom of the pipe goes first, leaving a channel that catches debris and then opens into the soil. A 50-year-old cast iron line in Houston is at or past the end of its life.

**Bellies.** The clay under the slab swells and shrinks, and a drain line laid at a slight slope can sag into a low spot. Water and solids collect in the belly, and the line backs up over and over no matter how many times it is cleaned.

**Tree roots.** Live oaks, pecans and anything else large send roots toward water. Any joint in a clay or cast iron line is an entry point. Roots fill the pipe and break the joint open.

**Foundation movement.** A lift, or just years of seasonal movement, separates joints and breaks pipe at the point where the line leaves the slab.

**Grease and wipes** are the fastest way to clog a line that was already compromised.

## The signs

- Backups in the lowest fixture in the house, usually a tub or shower, when another fixture is used.
- Slow drains in several rooms at once. One slow sink is a sink problem. Three is a line problem.
- Gurgling from toilets or drains.
- Sewage smell inside, under the house, or in the yard.
- A patch of lawn that is greener, wetter or sunken.
- Repeated clogs that come back a few weeks after cleaning.
- Foundation movement with no drainage explanation, which can be a leaking drain line softening the soil.

## What a camera inspection tells you

A plumber runs a camera through a cleanout and records the inside of the line. A locator on the camera head lets them mark the depth and position of each problem from above. You should receive the recording and a written summary of:

- Pipe material and condition, section by section
- Location and depth of any break, offset joint, belly or root intrusion
- Whether the line can be cleared and lined, or has to be replaced
- Where the line connects to the city system

Watch the video. A belly looks like standing water the camera submerges into. A break looks like soil or a gap. Roots look like roots. A plumber who cannot show you the video has not done the inspection.

## Repair options

| Option | What it means | When it fits |
|---|---|---|
| Clean and clear | Cable or hydro jet to remove the blockage | A clog, roots in a sound pipe, or buying time |
| Spot repair | Dig or tunnel to the one bad section and replace it | One break or offset, with the rest of the line in good condition |
| Tunnel under the slab | Dig from outside, tunnel under the foundation, replace the pipe from below, backfill | Lines under the slab where you do not want to break the floors |
| Pipe lining | A resin liner cured inside the existing pipe | Cracked or rooted pipe that still holds its shape. It does not fix a belly or a collapse. |
| Full replacement | New PVC line from the house to the connection | Old cast iron throughout, multiple failures, or a line that has been repaired before |

Tunnel work in Houston is usually done by crews who do only that, often as a subcontractor to the plumber. Ask who is doing the digging, whether the tunnel will be backfilled and compacted, and whether the plumber's warranty covers the sub's work.

## Permits, 811 and the city line

The City of Houston requires a plumbing permit for sewer line replacement, and a licensed plumbing company pulls it in its own name. Work in the public right-of-way needs additional permission. Any digging requires a Texas 811 locate request before the shovel goes in.

You own the private line from the house to the point where it connects with the city system. The city maintains the main. If your neighbors are backing up at the same time, call 311 before you pay for a camera. The city will check the main, and if the problem is there, the repair is theirs. Confirm the exact boundary of your responsibility with Houston Public Works, since it depends on where the tap is.

## Before you buy

A Texas home inspection does not include a sewer camera. On any house built before about 1980, any house with large trees near the line, or any house where the seller mentions past drain cleaning, order a sewer scope during the option period. It costs a few hundred dollars and it finds the one problem that can cost more than a roof.

## Getting a fair bid

Nobody should quote a sewer repair under the slab without a camera inspection. The bid should name the method, the footage, the pipe material, what gets opened and who restores it, the permit, the 811 locate, and the warranty on both the plumbing and the tunnel. Two bids with the same scope should land close. A bid far below the others has left something out.

## Frequently asked

**How do I know if my sewer line is broken?**

The usual signs are backups in the lowest fixtures, often a tub or shower, drains that are slow in several rooms at once, gurgling toilets, sewage smell inside or in the yard, unusually green or soggy patches of lawn, and foundation movement with no other cause. Any of these is a reason for a camera inspection.

**What is a sewer camera inspection?**

A plumber runs a camera on a cable through a cleanout and records the inside of the line, using a locator to mark the depth and position of any problem from above. It takes an hour or so, costs a few hundred dollars in Houston, and is the only way to know what the repair actually is.

**Who is responsible for the sewer line, me or the City of Houston?**

You own and maintain the private line from the house to the connection with the city system, and the city maintains the main. If several neighbors have problems at the same time, call 311 and ask the city to check the main before you pay for a private repair. Confirm the exact boundary for your property with Houston Public Works.

**Should I get a sewer scope before buying a house in Houston?**

Yes, on any house built before about 1980, and on any house with large trees near the line. A standard Texas home inspection does not include a camera. The scope is a separate service and it is the only inspection that can find a sewer problem that costs more than the roof.

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