Note to readers: This post was updated on July 30, 2026 to add clearer diagnostic signs, current cause breakdown, and links to our related sewer line guides. We refreshed the details below so the advice reflects how we approach this work today.
Your main sewer line is one of the most important pipes in your home – when it clogs, you’re usually looking at a professional main sewer line cleanout. This guide covers the warning signs of a main line clog, what typically causes it, and what to expect from a cleanout.
Signs you need a main sewer line cleanout
A clogged main line can cause a range of problems throughout your home, including:
- Multiple backed-up drains at once. When more than one fixture backs up simultaneously, they’re usually competing for space in the same clogged main line.
- An overflowing cleanout access pipe. If yours is in the yard, you may see wastewater surfacing around it.
- Water rising through drains or around the toilet when you flush. This usually means the clog is severe enough that wastewater is backing up toward the house.
- Sewage odor from your drains. Not a subtle sign – and not one to ignore.
- Pooling water near the cleanout. A sign that wastewater is backing up rather than draining forward.
- Sewage surfacing from a floor drain. Floor drains connect directly to the main line, so this is a clear signal.
- Water backing up into the shower when someone flushes. Inconvenient at any time, worse before work in the morning.
For a deeper look at diagnosing these symptoms, see our guide on hidden signs of a clogged main sewer line.
What causes main sewer line clogs?
- Old, cracked pipe. Aging sewer pipe lets wastewater seep out and debris build up at the crack.
- Tree roots. Common throughout Arcadia and the San Gabriel Valley, where mature trees are everywhere – it’s part of why we’re named Western Rooter & Plumbing.
- Foreign objects lodged in the line. Anything dropped down a drain or toilet over the years can eventually settle and block flow.
- Poor prior installation. Work done by unlicensed plumbers is a common root cause of recurring problems.
Fixing it yourself vs. calling a plumber
If the clog isn’t severe, some homeowners can handle it themselves – we cover the process step by step in how to fix a clogged sewer line. That said, we always recommend starting with a sewer video camera inspection so you know exactly what you’re dealing with before you start – tree roots, a crack, and a simple clog can all look the same from the surface.
What a professional cleanout involves
We’ve performed thousands of main sewer line cleanouts over more than 40 years in business. Every cleanout we do starts with a video inspection to confirm the size and location of the problem before we recommend a fix – whether that’s a standard cleanout, hydro jetting, or in more serious cases a trenchless repair.
How Western Rooter & Plumbing can help
We offer a complimentary sewer video camera inspection with every main sewer line cleanout to confirm the size and scope of the problem before any work begins. Call us at (626) 448-6455 before you do anything else – it could save you thousands.
