Symptoms
- Gurgling sound during or after flushing
- Gurgling when a nearby sink or shower drains
- Bubbles rise in the bowl water
- Slow draining along with the sound
Likely causes
- CommonPartially clogged drain ventA blocked vent stack on the roof forces air to find another path, bubbling through the toilet trap.
- CommonPartial clog in the toilet or branch drainA blockage downstream changes airflow and causes gurgling as water tries to pass.
- PossibleMain sewer line partial blockageA backup further down the system affects multiple fixtures, with the toilet gurgling first since it has the most direct path to the sewer.
What to do
- Notice whether gurgling happens only with the toilet or also when other fixtures drain, which points toward a shared vent or main line issue.
- Run a toilet auger through the trap to rule out a clog right at the toilet.
- Check if any roof vent pipes have visible debris, leaves, or nests blocking them, if safely accessible.
- Avoid running multiple fixtures at once (like a washing machine and toilet) until the issue is diagnosed, since that can worsen backups.
- Watch for gurgling or slow drains at the lowest fixture in the house, like a basement floor drain, which is a sign of a main line problem needing prompt attention.
Tools and parts
- Toilet auger
When to call a pro
Call a plumber for a camera inspection of the vent stack and main line if gurgling happens across multiple fixtures or doesn't clear with a simple auger pass.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.