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Common Causes of Sewer Line Blockage in North Carolina Homes

A main sewer line blockage is one of the most frustrating plumbing problems a homeowner can face. When your sewer system isn’t working properly, you could end up with slow drains, sewage backups, or even major damage to your home. The good news? Many sewer line blockages are preventable with proper care and maintenance.

At Three Way Plumbing, we make sure to get to the root of the problem—literally! We have drain cameras on every truck, so we can quickly diagnose the cause of your sewer line clog and clear it out before it turns into a bigger issue.

1. Tree Roots Invading Your Sewer Pipes

The #1 cause of main sewer line blockages is tree roots growing into the mainline. In North Carolina, where tree growth is abundant, roots naturally seek out moisture, and your sewer pipes provide the perfect environment. Over time, they can grow into the mainline, causing cracks, leaks, and severe line blockages.

Warning Signs:

• Gurgling sounds when you flush the toilet
• Slow drainage in multiple drains
• Sewage smells coming from your plumbing system

If left untreated, tree roots can completely clog your sewer line, leading to expensive repairs. Regular inspections with our drain cameras help detect root problems early.

2. Bellied Sewer Line Due to Ground Settling

A belly in the sewer line occurs when part of the mainline sinks due to ground settling over time. This creates a low point in the pipe where wastewater and debris can collect instead of flowing smoothly to the sewer system or septic tank. Over time, this stagnant water causes buildup, leading to sewer line blockages.

Signs of a Bellied Sewer Line:

• Frequent backups in multiple drains
• Slow-draining sinks, tubs, or toilets
• Standing water in areas of your yard

Our team can use drain cameras to inspect your sewer pipes and determine if a belly in the line is the cause of your sewer line clog.

3. Sewer Line Separation & Dirt Intrusion

Another major cause of mainline sewer blockage is when sewer pipes separate underground, creating gaps where dirt and debris can enter. Over time, dirt builds up in the pipe, restricting flow and causing backups.

These separations are often caused by:

• Shifting soil due to heavy rains or foundation movement
• Improper installation of sewer joints
• Aging connections that crack and pull apart

Warning Signs of a Separated Sewer Line:

• Frequent clogged drains throughout the home
• Sewage backing up into lower-level plumbing fixtures
• Foul odors coming from drainpipes or your yard

If dirt is getting into the sewer line, no amount of drain cleaning will fully resolve the issue. A professional plumber will need to inspect and repair the damage.

Note: How Blockages in the Home Can Lead to Mainline Issues

While issues like grease buildup, flushing the wrong items, and garbage disposals can cause drainage issues inside the home, they typically affect smaller drainpipes rather than the main sewer line. However, these smaller blockages can contribute to bigger issues by slowing the flow of waste as it moves toward the mainline.

The mainline is usually 4 inches in diameter, allowing it to handle all waste and wastewater from your home. Because of this size, simple blockages like grease, wipes, feminine products or paper towels are unlikely to stop up the mainline unless another issue—like tree roots, a belly, or a separation—is already present. When these materials get stuck in the mainline, they are usually catching on an underlying problem rather than causing the blockage on their own.

4. Older Pipes and Structural Damage

If you live in an older home, your sewer pipes may be more vulnerable to sewer line blockages due to age and material breakdown. Clay or cast-iron pipes are common in older homes and can develop:

• Cracks or leaks that allow roots to grow inside
• Weak joints that shift or separate over time
• Corrosion that narrows the interior of the pipes

Signs of Aging Sewer Pipes:

• Frequent clogged drains
• Sewage odors in your yard or basement
• Standing water near drain openings

If your home has older pipes, a professional plumber can assess their condition using drain cameras and recommend the best solution for long-term reliability.

5. Multiple Drains Clogging at Once

If multiple drains in your home are backing up at the same time, the issue is likely in the main sewer line, not just an individual drain. Since all waste and wastewater flow through the mainline, any blockage in the sewer line will affect all connected drains.

If plunging and household drain cleaners don’t work, call a professional immediately. Our team at Three Way Plumbing uses advanced drain cleaning techniques to clear your sewer line clog and restore proper flow.

Call a Professional Plumber for Sewer Line Blockages

Ignoring a blockage in the sewer line can lead to serious damage and costly repairs. That’s why at Three Way Plumbing, we equip every truck with a drain camera—so we can locate and fix the problem fast.

Whether it’s tree root intrusion, a belly in the line, or a sewer pipe separation, our plumbing services ensure your sewer system stays in top shape.

If you’re experiencing slow drains, strange odors, or repeated clogged drains, don’t wait for the problem to get worse. Call Three Way Plumbing today for expert sewer line inspections and repairs!

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