Drain vent obstruction

Sound timing across fixtures changed the investigation from a local clog to system airflow.

Several traps moved when another fixture discharged because the drainage system could not admit air correctly.

Flow restriction and pressure imbalance overlap but affect fixtures differently.

Shared drainage changes pressure across traps. The triggering fixture often matters more than the fixture making the sound.

The pipe network that carries wastewater while balancing pressure and blocking sewer gases.

Drain odor appears mainly under strong wind or pressure changes.

Shared drainage changes pressure across traps. The triggering fixture often matters more than the fixture making the sound.