Why a Toilet Gurgles When the Shower Is Running

If your toilet gurgles every time someone turns on the shower, it typically means the plumbing system is struggling to move wastewater and sewer gases efficiently. In many cases, this points to an issue with water flow, a clogged pipe, or the home’s venting.

Under normal conditions, wastewater from sinks, tubs, toilets, and showers flows downhill into your main drain. Vents—often running through the roof—allow air to enter the plumbing so water can drain smoothly. When air can’t move correctly, drains may “pull” air from another fixture, creating gurgling sounds.