enter image description here

My sister-in-law sent us a picture of this. It is in a closet in her finished basement and she isn't sure what it is or what it's connected to, but it is dripping. As a layperson, my only guesses are that it has something to do either with either a condensate line and/or plumping waste water up to the sewer line which I assume is above their basement level. Any help identifying it would be appreciated.

  • A wider shot might help. Other than being really crufty (is that a fungus growing off the top right?) and held together with zip ties, it's hard to make out what this might be. First guess was filter housing, but it did not hold up to a closer look.
    – Ecnerwal
    Jan 13, 2022 at 15:26
  • I think what looks like fungus is actually damage to the wood behind it. This is the only picture that I have of it unfortunately.
    – Trevor
    Jan 13, 2022 at 15:50
  • 6
    Whatever it is, it's messed up! ;)
    – Matthew
    Jan 13, 2022 at 16:02
  • Perhaps an inline condensate trap? Assuming the source is from furnace or humidifier and perhaps they are putting through a trap to the drain? Can't tell for sure as we don't see where the source comes from or the drain goes
    – Chris
    Jan 13, 2022 at 16:31

1 Answer 1


It appears to be a Plastic Water Softener Air Gap...what ever that is!

enter image description here


  • 7
    Wow... nice find.
    – FreeMan
    Jan 13, 2022 at 16:37
  • 4
    <3 "whatever that is". It's like an itsy bitsy laundry sink. Lets your water softener, dehumidifier, etc drain into a P trap without subjecting it to sewage backups.
    – jay613
    Jan 13, 2022 at 18:19
  • 8
    And the “air gap” functionality is to prevent the device that is draining from being able to siphon waste water back out.
    – Tim B
    Jan 13, 2022 at 21:08
  • 3
    This thing shouldn't be dripping. It seems to me there's a clog somewhere and it is backing up. Might need to look into it more closely.
    – Nelson
    Jan 14, 2022 at 2:35
  • 20
    How did you find that picture not knowing what it is? Jan 14, 2022 at 19:38

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