Dishwasher needs it's own drain.....

[Mark Rios]

n my current kitchen remodel job I"m moving the location of the dishwsher. I want to put in a separate drain for the dishwasher and not hook it up to the sink drain.

I have perfectly easy access to a 2" drain line directly under the floor (lots of room under the floor as well) and easy access to the wall behind the dishwasher. No encumbrances whatsoever. I've done lots of remodel plumbing but I've never done a separate dishwasher drain.

Does anyone have any info on installation and requirements of a separate drain for a dishwasher?

Thanks very much for any advice.

[Jamie Buxton]

Have you ever seen a standpipe? They're not uncommon for a washing machine. You can do the same for a dishwasher.

Here's a link to the installation instructions for a Fisher Paykel dishwasher. Look at page 4, option 1. http://usa.fisherpaykel.com/admin/pdfs/pdf_installations/526607O_DD_Install_USw.pdf

Note that you must include the P-trap, to keep sewer gases from coming out into the room.

[ken brueggestrass]

didn't look too closely at the pervious attached, but pay particular attention to page 4. Using the 'sink drain' as you describe benefits from the P trap that keeps gases at bay. Failure to replicate this in some manner will really stink up the joint.

[Mark Rios]

That looks great thanks.

So there seem to be no tricks really, just a straightforward drain (which would of course include p-trap). I'd probably tie a vent in as well. I just need to keep an air gap somehow right?

Thanks very much again.

[Jamie Buxton]

That looks great thanks.

So there seem to be no tricks really, just a straightforward drain (which would of course include p-trap). I'd probably tie a vent in as well. I just need to keep an air gap somehow right?

Thanks very much again.

The top of the standpipe is open, and the hose from the dishwasher just drops into it. Often there's a J-shaped rigid tube on the end of the dishwasher hose to prevent the rubber hose from closing off as it tries to turn a sharp corner. (On the FisherPaykel installation page I cited, you can see a plastic thingy which helps the hose make the turn, but not collapse.) Air can enter the standpipe past the dishwasher hose, and that helps prevent the P-trap from siphoning empty. On the sewer side of the trap, the usual venting rules apply: you're supposed to have a vent pipe right where the drain goes inside the wall.

[Chip Olson]

I built a temporary cabinet for my dishwasher out of a couple slabs of MCP and a piece of postform countertop. Drain is via a standpipe, as described, into the drain stack that's going to be for the sink and dishwasher when I get these cabinets finished. Works just fine.