Plumbing · Common problems · Updated November 2026
Drains Keep Backing Up: Causes and When to Call a Plumber
A single drain that clogs now and then is usually a local problem. Drains that back up again and again, or several fixtures backing up at once, often point to a problem in the main sewer line.
If sewage is backing up into the house, stop running water and flushing toilets, keep children and pets away, and avoid touching the water. Call a plumber right away.
What the pattern tells you
| What happens | Likely location |
|---|---|
| One sink or tub is slow | Clog in that fixture's drain or trap |
| Toilet gurgles when the sink drains | Partial clog or venting problem |
| Water comes up in the tub or floor drain when you flush or run the washer | Main sewer line blockage |
| Several fixtures slow at once, especially on the lowest floor | Main line |
Common causes of repeat clogs
- Grease, food scraps and coffee grounds in kitchen drains.
- Hair and soap in bathroom drains.
- "Flushable" wipes and paper products.
- Tree roots growing into an older sewer line.
- A sagging or broken sewer pipe.
What you can safely try
- Use a plunger or a hand drain snake on a single slow drain.
- Clean sink and tub strainers and pop-up stoppers.
- Avoid repeated chemical drain cleaners; they can damage pipes and are dangerous if a plumber then has to open the line.
When to call a pro
Call a plumber for any backup into a tub or floor drain, several slow fixtures at once, or clogs that keep returning. Ask about a sewer camera inspection ($100–$500), which shows roots, breaks or sags. Drain cleaning runs $95–$500; sewer line repair or replacement runs $50–$250 per foot, according to our plumbing cost guide.
Cost figures are national ranges from the sources listed in our plumbing cost guide, not a quote from FixFinch or any contractor. This article is general information to help you decide on next steps. It is not an inspection or professional advice; a qualified pro who sees the problem in person can tell you what is actually going on. Calls connect you with an independent service provider in our network. FixFinch is not a contractor and does not perform the work.