My kitchen sink does not have an overflow, but the basket has an overflow connection which is capped off with a screw on cap which encloses a shallow cup shaped rubber diaphragm, which appears to exist to allow air to escape. It is now rather old, and starting to fail, resulting in flooding under the sink. Two questions: 1. what is the rubber valve called? 2. is there a more reliable system that I can use? See photos below:

the overflow cap with diaphragm

the basket with overflow pipe

  • Would get a complete screw on cap as the same size as that screw on ring and rubber cap.
    – crip659
    Jul 25, 2022 at 14:48
  • 1
    I guess the leak was from the rubber end piece, and I would get a blank cap to seal off the overflow pipe as it is normally unnecessary.
    – r13
    Jul 25, 2022 at 16:15
  • Are you sure that was not a type of air admittance valve? That doesn’t look like the AAV’s I have worked with but it’s location up high it makes it a possibility.
    – Ed Beal
    Jul 25, 2022 at 19:14
  • It looks like it is meant to allow air to escape rather then allow air in (the valve is placed in the ring such that it’s externally concave. It is a double sink, by the way, so the other sink has one too, so I figure that if I seal off this one, then air can still escape fro the other.
    – darasd
    Jul 25, 2022 at 20:11


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