Sucking air in: If there is a clog, the flow of the water from the shower to the sewer drain can create a vacuum. This vacuum effect can be strong enough to actually suck air down through the toilet p-trap, causing a gurgling noise.

Why does my toilet bubble when I run my sink faucet?

When a toilet gurgles, it indicates that negative air pressure (suction) is building up in the drain line, creating an airlock of sorts. In a well-functioning drain system, air flows freely through the lines, preventing negative air pressure, so waste runs smoothly down and out.

When my bathroom sink is running Why is my toilet gurgling?

What Causes a Toilet to Gurgle? The cause of your toilet gurgling is a blocked line somewhere. A clog is creating negative air pressure, Instead of air flowing through the lines,the air pushes back and causes the gurgling sound. Sometimes, you’ll also see the toilet water bubble.

How do you tell if your sewer vent pipe is clogged?





How to Tell if Your Plumbing Vent is Clogged

  1. A Primer on Plumbing Vents. …
  2. Water Takes A Long Time to Drain. …
  3. Dry and Empty Toilet Tanks. …
  4. Foul Smells. …
  5. Gurgling or “Glugging” Sounds as Water Goes Down the Drain. …
  6. Get Those Clogs Out of Your Plumbing Vent ASAP.