Our kitchen sink has an extra faucet hole, where I'd like to install a small tap for filtered water. But there is a stub of some old fixture in the hole. (I don't know what this thing is so I am just calling it 'the junk item')

Junk in unused hole

When I look underneath, I see that the grey drain hose from the dishwasher is attached to this junk, as is the black hose that leads to the garbage disposal.

Front view:

Front view

Upward view: Upward view

I understand having a big loop in the drain prevents backflow and odors, and I guess attaching the hose-joint under the countertop keeps it well elevated. But could I move the joint all the way inside the cabinet instead, to free up that hole for a new faucet?

For example could I attach it to the back wall, just beneath the countertop? This looks really simple but I have zero plumbing experience; what are the potential pitfalls here?

Not sure if I'm using the right vocabulary here, but hopefully the annotated pictures make it clear if the words aren't. Thanks!

  • Pretty sure that's a vent for the dishwasher. I wouldn't mess with it..somebody in the past musta determined it was needed.
    – Kyle B
    Sep 26, 2021 at 2:00
  • 2
    That's a fully functional air gap, not "a junk item" nor a "stub of an old fixture."
    – Ecnerwal
    Sep 26, 2021 at 2:54
  • If you have a soap dispenser on the other side, there are combination air gap/soap dispensers out there. That said, the few I’ve seen are pretty blocky. Sep 26, 2021 at 15:41

1 Answer 1


This is an air gap. There are two ways to prevent backflow of sewage from a dishwasher - a "high loop" and an air gap.

Generally speaking, older installations have traditional air gaps and newer ones use a high loop. But as I understand it, some jurisdictions may require a traditional air gap. If yours allows a high loop, then you should be able to:

  • Remove the black hose.
  • Connect the dishwasher hose directly to the disposal - you may need an adapter which normally comes with the disposal and/or dishwasher.
  • Mount the hose so that the loop goes as high as possible, but at a minimum above the bottom of the sink.

Once you do that, you can use the hole for other purposes.

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