We live on the second floor of an 11-floor condo building built in 1960. Six times in the last five months dirty water from the building comes up through our sink and overflows to the floor if we are not at home bailing water. Is there a device strong enough to place over the sink drain to prevent water from coming into the sink? Or is there another way to keep the water away while the building works on a permanent solution?

Only thing I can think of at this time is a check valve... see pic.

Although not ideal... installation of a check valve will stop backflow while not at home.. ;) and still allow your sink to drain when you need it. I would install this after the ptrap outlet. Easy install...if have PVC pipes.. if not.. what kind of pipe is present..

Let me know if any questions... Mark

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