Plumbing – How to hook up the dishwasher drain properly

dishwasherdrainplumbing

The problem

I am installing a new Bosch dishwasher and have run into a conundrum hooking up the drain. The parameters are the following:

  • The dishwasher drain hose has a rubber bit on the end marked 1/2" and 3/4". It steps directly from 3/4" to 1/2" without an intermediate 5/8" level. The dishwasher is otherwise completely installed, so I would prefer not to pull it out to put on an entirely new hose.
  • The air gap has a 5/8" inlet and 7/8" outlet.
  • I want to drain into a garbage disposal with a 1" inlet.

This leads to two problems:

  • The drain hose appears not to fit the air gap inlet. I suspect I could jam it onto the air gap inlet with enough force, but I'm worried about longevity.

    I do not mind replacing the air gap, but I've been unable to find one that had a 1/2" or 3/4" inlet and 1" outlet. Everything I've found, both locally and on the Internet, has 5/8" inlet and 7/8" outlet.

  • I need some way to connect the air gap outlet to the differently sized inlet on the disposal or (less preferred) some other part of the drain under the sink. I only need a couple of feet of hose.

The previous dishwasher had no air gap at all; it connected directly to the disposal (which led to at least one adventure I'd rather not repeat).

Right now I've taped the hose to drain into the sink, so do I have some time to do it right.

I'm puzzled because this seems like a common situation, so I wonder what I'm missing.

Sketch

Here is the situation. The red arrows are the two connections I am trying to make.

sketch

Photos

End of dishwasher hose:

hose

Air gap:

air gap

Disposal inlet (the rag is simply to prevent leakage so we can use it while I solve this hookup problem):

disposal

Best Answer

I have had my Bosch dishwasher for about a year using the same setup you contemplate, so I'm familiar with the exact drain connector you have on the dishwasher hose. On mine, there was something of a taper between the 1/2 and 3/4 section and being rather flexible rubber, and I had no difficulty stretching the 1/2 section of the fitting to fit on the 5/8 gap fitting. I then tightened down the hose clamp with a hex bit on my cordless driver. The clamp was tight enough to somewhat compress a groove into the rubber, and I tugged on the thing as hard as I could. It isn't coming off IMHO. I'm at work, but can send a picture later if you need.

I understand you are worried somewhat about the quality of the connection. You could get a 1/2 to 5/8 adapter like this:

enter image description here

But that would entail 3 hose clamps and a section of 5/8 ID hose to connect between the adapter and air gap. That seems like more points of failure. At any rate, I think you already have what you need to get this working.

Related Topic