Why Your Toilet Gurgles When the Washing Machine

Gurgling noises from a toilet when the washing machine runs are more than an annoyance—they signal a plumbing system that’s under strain. The most common culprits are venting problems, clogged drains, or a shared drainage line that’s not handling simultaneous water activity well.

When the washing machine drains, it releases a large volume of water and air into the sewer line. If the vent stack is blocked or undersized, air has nowhere to escape, creating negative pressure that pulls air through the toilet trap, producing a gurgling sound. A similar effect can occur if the main drain is partially clogged, causing slow drainage and air pockets to form in the toilet and other connected fixtures.