My drains gurgle. What does that mean?
Gurgling is an early warning. It costs much less to look at now than after it turns into a backup.
The sound is air being dragged through a trap. A drain needs air behind the water to flow smoothly. When the drain line is partly blocked, or the vent that feeds it air is, the water pulls air from the closest trap instead, and you hear it.
Where it gurgles tells you a lot. One drain gurgling on its own usually means a problem in that drain. A toilet that gurgles when the bath empties, or when the washing machine pumps out, points at the main line shared by both.
Bad smells along with the gurgle suggest a trap is being siphoned dry, which lets sewer gas into the room.
Want it looked at?
Note which drain gurgles and what else is running at the time, the washer, a shower, a flush. That narrows it fast.