Why are all my drains slow at once?
Updated August 2026
When every drain in the house slows down at the same time, the blockage is not under one sink; it is in the main sewer line, most often from tree roots that have grown in through a pipe joint. Grease buildup and a bellied or collapsed section are the other common causes. A single fixture backing up is a local clog, but toilets, tubs, and sinks all draining slowly together, especially with gurgling, means the one pipe they share is choked and needs clearing now.
Safety first: a main-line clog is a health issue, not just an inconvenience. Once the line is fully blocked, the next flush backs raw sewage up into the lowest drain in the house, usually a basement floor drain or a first-floor tub. Stop using water the moment you see backup or hear gurgling, keep kids and pets away from any standing wastewater, and wear gloves and ventilate when you clean it. Sewage carries bacteria, so anything porous it soaks should be discarded.
Causes, most likely first
| Cause | How likely | The fix | Typical cost |
|---|---|---|---|
| Tree-root intrusion at a pipe joint | Most common | A pro runs a cutting auger, then usually a camera to see the damage. Roots regrow, so this repeats. | $150–500 to snake |
| Grease and sludge buildup | Common | Hydro-jetting scours the pipe walls clean, where a snake only punches a hole through the grease. | $350–600 to jet |
| Flushed wipes or foreign objects | Common | So-called flushable wipes and paper towels mat together and jam the line. An auger clears them. | $150–400 |
| Bellied (sagged) section of pipe | Occasional | A low spot collects waste and clogs repeatedly. A camera locates it; excavation or lining repairs it. | $1,500–6,000+ |
| Collapsed or broken pipe | Occasional | Old clay or cast iron cracks and caves in. Full replacement or trenchless lining is the fix. | $4,000–15,000+ |
Check these first
- Confirm it is everything, not one fixture. Flush a toilet and watch whether a nearby tub or shower drain bubbles or rises: that cross-talk is the classic main-line sign.
- Start with the lowest fixtures. A basement or first-floor drain is where a main clog shows first and where backup appears.
- Stop adding water. Every flush and every load of laundry pushes more waste against the blockage and closer to a backup.
- Find and check the cleanout. A capped pipe in the basement, crawlspace, or yard lets you or a pro reach the main directly.
- Think about the yard. Large trees near the sewer path, or a line over 40 years old, make roots and collapse far more likely.
Prevent it next time
A main-line clog is the kind of failure worth getting ahead of, because the cleanup is measured in thousands. Have the line snaked or jetted every 18–24 months if you have mature trees or a history of clogs, and get a camera inspection every 3–5 years to catch roots and bellies before they block. Never pour grease down the drain and never flush wipes. A clay or cast-iron sewer lasts 50–60 years, so an older home is on borrowed time and belongs on a schedule.
When to call a pro
This is a call-a-pro symptom from the start. A rented drum auger rarely reaches a root mass 30 to 60 feet out, and a full blockage with active backup is not a DIY afternoon. Expect $150–500 to snake the main, $350–600 to hydro-jet it, and $250–500 for a camera inspection that names the cause. If the camera finds a collapse or a belly, budget $4,000–15,000 or more for excavation or trenchless lining, and get more than one quote before committing.
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Stop chasing symptoms, free for 30 daysFrequently asked questions
Can I clear a main sewer line clog myself?
Usually not, and it is easy to make things worse. A partial clog you can sometimes free through the cleanout with a rented drum auger, but a full blockage, a root mass, or anything past 25 feet needs a professional machine and often a camera to confirm the cause. Chemical drain cleaners do almost nothing to roots or grease in a large pipe and just leave caustic water sitting on the clog. If every drain is slow and a fixture is backing up, call a drain service.
How do I know if it is tree roots or grease?
The pattern and the fix differ. Roots usually cause a gradual slowdown over months and return on a seasonal cycle, and a cutting auger pulls out visible root hair. Grease builds up in kitchen-heavy homes, coats the pipe in a slick layer, and responds far better to hydro-jetting than to a snake. The only way to know for sure is a camera inspection, which is why plumbers run one after clearing the line: it shows roots, grease, or a broken section directly.
How much does it cost to replace a collapsed sewer line?
It is the expensive end of plumbing. A straightforward dig-and-replace of a residential sewer typically runs $4,000 to $10,000, and a long run under a driveway, mature landscaping, or a city sidewalk can push past $15,000 to $25,000. Trenchless methods like pipe lining or bursting sometimes cost a bit more per foot but spare the yard. A camera inspection first, around $250–500, tells you whether you face a spot repair or a full replacement.