Broken Sewer Line: What the Signs Look Like in a Florida Home

Most guidance on broken sewer lines was written for houses with basements, and it describes symptoms a Florida homeowner will never see. Here the drainage runs under a concrete slab in sandy fill with a high water table, and a break announces itself differently.

The Florida signature

A sinking or soft spot in the yard. When a line breaks below grade, water leaves the pipe and soil enters it. Sandy fill washes into the break and is carried away, leaving a void that eventually settles at the surface. A depression that follows the line’s route from the house toward the street is one of the clearest signs there is. A homeowner given advice on exactly this said the practical version: “Get a plumber to run a camera through your line and see if it’s broken or sinking.”

Drain flies. Small dark flies that appear indoors and keep coming back breed in the saturated, nutrient-rich soil around a break. They are not a hygiene problem in the kitchen; they are an indicator of wet ground under the house.

A smell that has no source. Gas from a break under the slab rises through expansion joints and hairline cracks, so it fills a hallway rather than a bathroom and cannot be traced to a fixture. It typically worsens after heavy rain as the water table pushes upward.

Repeat backups. A line cleared once and quiet for years was blocked. A line that blocks again within a year has a defect that keeps catching material.

A patch of lawn that is greener or wetter than the rest, fed by what is leaking out.

A floor that sounds hollow or feels soft, where fill beneath the slab has washed into the pipe.

What is happening in the pipe

Defect	How it starts	What it produces
Crack or fracture	Corrosion, ground movement, settlement	Leakage, root entry, soil washing in
Channelling	Sulfuric acid corroding cast iron from the crown down	A trough instead of a bore; constant catching
Offset joint	Sections shifting apart as fill settles	A step that catches solids
Belly or sag	Settlement under the pipe	Standing water; solids drop out
Root intrusion	Roots entering an existing opening	Blockage, and the opening widening
Collapse	Advanced corrosion or crushing load	Total or near-total blockage

Roots deserve a note of their own because of what they prove. As a widely upvoted comment put it: “Definitely roots. They can only get inside from a break in the pipe.” Finding roots is finding an opening.

Why the material and the year built matter so much here

The Cast Iron Soil Pipe Institute puts cast iron drain pipe at 50 to 75 years of service life; in South Florida’s permanently damp sandy fill, practice runs nearer 40 to 50. PVC became standard in Florida residential construction in the late 1970s, and roughly 35% of the living units in South Florida built in the 1960s and 1970s went in with cast iron.

That gives a threshold worth knowing: a Florida house built before about 1975 very likely has original cast iron underneath, now at or beyond its service life. Broward is full of exactly that stock — Hollywood’s median year built is 1969, Fort Lauderdale’s 1972, Lighthouse Point’s 1968, according to U.S. Census ACS 2024 five-year data, table B25034.

Confirming it

There is one method, and it is inexpensive relative to what it settles. A camera on a push rod enters through a cleanout, travels the line, and a surface locator marks the position and depth of any defect. The output should be recorded footage that names the defect and the distance — “offset at 34 feet, five feet deep” rather than “the line is bad.”

Insist on a copy. Recorded video can go to a second contractor for an independent read, which is the most effective answer to the reasonable worry that a diagnosis is a sales pitch.

What it costs to fix

• Spot repair, shallow yard line — $1,500 to $4,000
• Spot repair, deep or under hardscape — $4,000 to $9,000
• Under-slab repair inside the house — $6,000 to $18,000
• Full lateral replacement — $10,000 to $30,000, more if the run enters public right-of-way

Anything crossing the property line brings Broward County into scope: a Road Cut and Restoration Permit covering the paved area including signage and striping, and certified as-builts signed and sealed by a Professional Land Surveyor registered in Florida. Those requirements are why a street-side job costs a multiple of an in-yard one.

“A sinking line in sand is a clock. The break is not getting smaller and the void under the slab is not filling itself back in.”

If your yard is settling along the line or the smell keeps coming back, request a free quote.