Cracked or broken sewer pipe: how serious it is, and how it's fixed
Updated
The short answer
A cracked sewer pipe ranges from a hairline crack that can be monitored to a broken section leaking sewage into the soil. Signs include several slow drains, sewage smell, and wet ground or lush grass over the line. A camera confirms it; cracks in pipe that still holds its shape can often be lined, while broken or collapsed sections are dug out.
How urgent · It depends
A hairline crack in sound pipe can usually be monitored. An open, growing or leaking crack should be repaired soon, before it lets roots in or washes out the soil around it. Sewage in the yard, under the floor or backing up inside means act now.
Health & safety
A broken sewer pipe leaks sewage into the soil and, under a house, can feed mould and moisture in floors and walls. Avoid contact with wet ground over the line, keep children and pets away from it, and ventilate any area with a persistent sewage smell until the source is found.
What cracks a sewer pipe
Several different problems produce the same symptom and need completely different fixes. Work down the list — each one names the check that rules it in or out.
- 1
Tree roots
Roots enter through tiny gaps and joints, then thicken and pry the pipe open. A hairline crack can become a split within a few growing seasons.
How to tell
Roots on the drain cable, and trees between the house and the street. - 2
Ground movement and settlement
Expansive clay, settling fill, freeze-thaw cycles and nearby excavation all move the soil a pipe rests in. Rigid materials like clay and cast iron crack rather than flex.
How to tell
Cracks at several points, often with offsets or a belly nearby, and problems that started after construction or a wet season. - 3
Age and corrosion
Cast iron corrodes and thins until it splits along its floor; clay becomes brittle; Orangeburg softens and blisters. Past a certain age, cracks appear along the line rather than at one spot.
How to tell
A house built before the mid-1970s, and a camera showing deterioration at many joints or along the pipe floor. - 4
Heavy loads and impact
A shallow line under a driveway, heavy equipment during construction, or a vehicle crossing a lawn can crush or crack the pipe beneath.
How to tell
Damage directly under a driveway, a new patio or a construction access route. - 5
Poor installation
Pipe laid without proper bedding, or joined badly, carries stress points that crack under the normal weight of soil above.
How to tell
A relatively new line that already shows cracks or offsets at joints.
Signs of a cracked or broken sewer pipe
The signs overlap heavily with a collapse, because a crack is often the stage before one. What a crack adds is leakage: water and sewage escaping into the soil, and soil and roots getting in.
| Inside the house | Outside, over the line |
|---|---|
| Several slow or gurgling drains | Soggy ground even in dry weather |
| Clogs that return after cleaning | A strip of unusually lush, green grass |
| Sewage smell in a basement, crawl space or lower bathroom | Sewage smell near the cleanout or over the line |
| Mould or damp along baseboards that keeps coming back | A depression or sinkhole forming |
| Rodents or insects appearing at floor drains | New cracks in a nearby slab or foundation |
How serious is a cracked sewer pipe?
Crack is a broad word on an inspection report. What matters is the type, whether it's leaking, and whether the pipe around it still holds its shape.
| What the camera shows | How serious | Usual response |
|---|---|---|
| Hairline crack, pipe round, no leak or roots | Low | Monitor; re-inspect in a year or two |
| Circumferential crack at or near a joint | Moderate | Spot repair or line if roots or leakage appear |
| Longitudinal crack along the pipe | Moderate to serious | Line the section if the pipe holds its shape; otherwise replace |
| Open crack with roots or visible soil | Serious | Repair soon — spot repair or lining |
| Broken section, missing pieces, deformation | Serious | Excavate or burst the section |
| Cracks along much of the line | Serious | Line or replace the run |
A broken sewer pipe under the house
In slab-on-grade homes, the main drain runs under the concrete floor before it becomes the lateral outside. A crack there hides for longer and shows itself differently: spongy or lifting flooring, tiles that crack or loosen, baseboards separating, a sewage smell with no obvious source, mould that returns along walls, and sometimes growing cracks in the slab.
Plumbers confirm under-slab drain leaks in three ways. A camera inspection shows the crack and its position. A hydrostatic test plugs the drain at the foundation with an inflatable test ball, fills the under-slab piping with water, and watches the level for 15 to 30 minutes — if it drops, there's a leak, and isolation testing narrows down which section. Test prices commonly run about $250 to $500. A smoke test pushes harmless smoke through the system and shows where it escapes.
Repairs under a slab are where method choice matters most. Breaking out the floor to replace pipe is the most disruptive. Lining the drain from inside avoids demolition if the pipe holds its shape. Some contractors tunnel under the foundation instead of breaking the floor, and some reroute the drain entirely. Ask for prices on at least two approaches.
How cracked and broken sewer pipes are repaired
| Repair | When it fits | Planning range |
|---|---|---|
| Monitor | Hairline crack, no leak, sound pipe | Camera inspection every year or two, about $150–$500 |
| Spot repair | One or two damaged sections, rest of the line sound | $1,400 – $5,500 under lawn |
| Pipe lining (CIPP) | Cracks along a run of pipe that still holds its shape | $4,750 – $13,800 for 50 ft |
| Pipe bursting | Brittle, broken or deformed pipe along the run | $4,450 – $12,600 for 50 ft |
| Dig and replace | Broken sections plus a belly or grade problem | $5,550 – $14,700 for 50 ft under lawn |
Planning ranges including permit and camera inspection, from the same engine as the cost calculator. Not quotes; restoration under concrete and the street section add more.
Is a cracked sewer pipe covered by insurance?
The crack itself usually isn't under a standard homeowners policy, because cracks from age, roots, corrosion and settling are excluded. Some policies do cover sudden resulting damage to floors and walls, often with limits on the cost of tearing out a floor to reach the pipe. A service line coverage endorsement commonly covers repairing an outdoor lateral up to its limit if the problem wasn't known before the policy began.
Who is responsible depends on where the crack is: the owner for the pipe on their property, and often for the section under the sidewalk and street too, depending on the city.
Frequently asked questions
- How serious is a cracked sewer pipe?
- It depends on the crack. A hairline crack in pipe that still holds its shape can often be monitored. An open or leaking crack, roots growing through it, or a crack along the pipe's length should be repaired soon, and a broken or deformed section needs replacing.
- How do you tell if you have a cracked sewer pipe?
- Several slow drains, recurring clogs, a sewage smell low in the house, and wet ground or unusually green grass over the line are the common signs. A camera inspection confirms it and shows the crack's position and type.
- Can a cracked sewer pipe be repaired without digging?
- Often, yes. If the pipe still holds its shape and a camera can pass, a cured-in-place liner seals cracks without excavation. Broken, deformed or collapsed sections still need a pit or excavation.
- How much does it cost to fix a cracked sewer pipe?
- A spot repair of one section typically runs about $1,400 – $5,500 under a lawn. Lining 50 feet runs about $4,750 – $13,800, and replacing 50 feet under lawn about $5,550 – $14,700.
- How much does it cost to fix a broken pipe under the house?
- It depends heavily on the method. Diagnosis with a hydrostatic test commonly costs $250 to $500. Lining a drain under a slab avoids breaking the floor; trenching through the slab adds roughly $300 to $350 per foot before the pipe work itself.
- Is a cracked sewer line covered by homeowners insurance?
- Usually not the crack itself, which is treated as wear, corrosion or settling. Some policies cover sudden resulting damage inside, and a service line endorsement can cover repairing the outdoor line up to its limit.
- Can you get sick from a broken sewer line?
- Sewage carries bacteria and viruses, so contact with contaminated soil or backed-up water can cause illness, and leaks under a house can feed mould. Avoid contact, keep children and pets away, and get the leak repaired.