Gurgling occurs when air and water are not moving normally through the drain system. If it happens at only one fixture, a nearby restriction may be involved; if several sinks, a shower, or a toilet react to one another, plumbing venting or a deeper main-drain restriction becomes more likely.
Find out whether one drain or several are affected
Run one fixture at a time and listen to the others. A gurgle isolated to one sink after it drains points closer to that trap or branch, while several interacting fixtures broaden the problem.
Slow drainage plus gurgling suggests a restriction
Hair, grease, soap, or other buildup can allow some water through while forcing air to bubble. Clean traps or accessible components appropriate to the fixture before using harsh drain chemicals.
Multiple fixtures gurgling can point to venting or the main line
If a toilet bubbles when the washer drains or a sink gurgles when the shower runs, the system may be pulling air through another trap. A blocked vent or restricted main line needs broader diagnosis.
Sewage backup or several slow drains needs prompt action
Stop using water if wastewater begins rising through showers or floor drains. Avoid opening cleanouts that may be pressurized or contacting sewage; a main-line blockage can require professional equipment.
Sources
- U.S. Environmental Protection Agency WaterSense — Home Maintenance — Household maintenance related to water, leaks, toilets, pressure, and efficient use.