Sorry I should have said. Not directly, but tap into it. It will already have the trap and sink pipes attached.

What exactly are you trying to accomplish with such a hookup?

Ditto.

chillilover, do you know what a slip joint is?

If your requirement is for a drain hose from a dishwasher, then say so and people will comment on that more specifically than what your questions asked.

There is already a dishwasher connected there. It's for a small condensation pump.

Cut and glue a wye in. Glue in a 1-1/2 x 1/2 FIP red bushing in side tap. Screw in a 3/8 barb by 1/2 mip adapter

Probably should not be connected direct to the drain line. An air gap of some sort would be required to prevent back flow syphoning of drain water.

Pump has check valve. Would that prevent the backflow then?

chillilover, do what zl700 said.
Or connect it however it makes sense, to the drain pipe under the sink, but above the P trap.

chillilover, you can disregard what joed said.

I'll explain why. An indirect drain is by definition already in existence when you connect something (like a dishwasher) to the pipe under the sink, above the P trap. Search on this term : "Dishwasher Wye" or "Dishwasher Tee" and you'll see how millions of dishwashers are plumbed to sink drain pipes without even going thru the garbage disposer. There is air, open to the room, and this is the definition of an indirect drain. You hear gurglng coming up thru the sink strainer. Go see your washing machine standpipe and you'll see another indirect drain. It has air, open to the room, so that when drain water comes in, air can leave the volume occupied by the water coming in. You hear it gurgle when it drains. That is it. Nothing more. So, yes, it is correct to say, " should not be connected direct to the drain line..." but this correct information was not given to you in a way that made sense. The only way to "connect direct to the drain line..." is if you had a separate (dedicated) P trap for it --- which you don't have!

Then, when joed said "An air gap of some sort would be required ..." he is again 100% correct, but it's information given in a way that creates confusion not clarity. An air gap already exists when an indirect drain exists. An air gap is a space that lets air come out when water comes in, so it is not a product to buy but a space to maintain. Again go look at your washing machine standpipe and you'll see that nobody taped shut the air gap (spacing) that lets all the gurgling noise (air) come out when the washing machine drains itself. So, yes it is correct to say "air gap required" but it is doesn't help understanding. EEspecially true, since you already got the answer you needed in the preceding post, so it appears more as a contradiction than as a confirmation. Duh.

Since you asked about "check valve" it proves that joed's post appears to you more as a contradiction than as a confirmation that zl700 was right.

Don't overthink this: just go connect it.

hope this helps.

There is already a wye with the dishwasher hooked up so theres no room avove the p trap for another wye.

use the same Wye for both.

Sorry, I don't know much about plumbing but how would I do that?

"An indirect drain is by definition already in existence when you connect something (like a dishwasher) to the pipe under the sink, above the P trap."

A tap into a drain line below the flood level of the fixture served does not meet the requirments for an indirect wast.