Sewer Line Leak Under the Slab: Warning Signs for Arlington Homes

The drain pipes under your slab carry water and waste out to the sewer. They are not under pressure, so a crack or bad joint leaks only when you use water. Your water meter may not show anything. Instead, the signs are odors, slow drains and damp spots. Many Arlington homes from the 1950s to the 1970s still have cast iron drains under the slab, and Arlington's clay soil moves with wet and dry seasons. If you suspect a drain leak, call (817) 285-5426 for sewer leak detection.

What causes a sewer leak under the slab?

Common causes are cast iron pipe that rusts and cracks with age, soil movement that pulls joints apart or bellies the pipe, tree roots that find a small gap, and heavy grease or wipes that put strain on a weak spot. Foundation repair can also shift drain lines under the slab.

Clay soil in North Texas swells when wet and shrinks in drought. That movement stresses every pipe under the house. Our guide to drought and slab leaks explains why. If you just had foundation work done, see plumbing tests after foundation repair.

What are the signs of a sewer leak under the slab?

Watch for a sewer smell inside the house that has no clear cause, slow drains in more than one fixture, gurgling toilets, damp or stained flooring that gets worse after laundry or showers, new cracks in walls or floors, and insects such as drain flies or roaches coming up from below.

• Sewer odor near a floor, cabinet or wall, not just at one drain
• Drains that back up or gurgle, even after clearing
• Damp spots that grow after heavy water use
• Mold or a musty smell along a bathroom or kitchen wall
• New cracks in tile or drywall
• Pests near floor drains or tub access panels

How is a sewer leak different from a water line slab leak?

A water line leak is on a pressurized supply pipe. It runs all the time and makes the water meter move with every tap off. A sewer leak is on a drain pipe. It only leaks when water goes down the drain, so the meter stays still. The fixes and the tools to find them are different, so it helps to know which one you have.

Do the meter test in our high water bill guide. If the meter moves, read our guide to slab leak signs. If it does not, a drain leak is more likely.

How is a sewer leak under the slab found?

A technician runs a waterproof camera through a cleanout to see inside the pipe. The camera shows cracks, separated joints, roots and low spots, and a locator marks its position on the floor. A drain line test, where the line is plugged and filled, can confirm a leak when the camera alone is not enough.

Read more in our guide to sewer camera inspections in Arlington.

How is a sewer leak under the slab fixed?

A small crack can often be fixed with a spot repair, where a section of floor is opened and the pipe is replaced. Longer damaged runs may be lined from the inside with a trenchless liner, or rerouted. The best choice depends on the pipe material, the length of damage and the floor above.

Compare options on our slab leak repair page.

How much does a sewer camera inspection cost in Arlington?

A sewer camera inspection in Arlington usually costs $150 to $400. Basic leak detection runs about $150 to $400, and slab leak detection about $250 to $600. You get the price before work starts.

General estimates for Arlington, TX in 2026. Your exact price is confirmed before any work begins.