Fill both sinks with a few inches of water, then pull both plugs. If water drains slowly from both, the clog is deep in the common trap or main line. If only one side drains poorly, the blockage may be near that sink’s individual strainer.

A double kitchen sink is a convenient setup—until water starts backing up into both basins. Because the two sinks share a common drainpipe, a clog often reveals itself when you run the disposal or wash dishes on one side, and dirty water rises through the other. Before you reach for harsh chemicals, try these proven steps.

A double sink requires sealing the opposite drain to create proper suction. Use a wet rag or a second plunger pressed firmly over the unused drain. Then plunge the clogged side vigorously for 20–30 seconds. The trapped air forces pressure through the shared pipe.