My waste pipe in my kitchen is at 21 inches. I am installing a dishwasher and have not found any fittings that will work in this application.I can redo the drain to come into the floor of the cabinet. Is this OK to do or is there a dishwaser hook up that will work that I haven't found?

Putting a trap at the cabinet floor level is fine, gives you a good air gap. Use a trap, a trap insert with a threaded fitting and a barb connector, do it all the time.

Dishwasher discharge goes into Garbage Disposer side inlet. If you don't have Garbage Disposer installed than use Branch "T" piece that is designed for this application. Back to you. Milo

I am talking about rerouting the whole waste drain. It now enters through the wall at back of cabinet but I can access it from basement to come up through bottom of cabinet instead. I have no garbage disposal and the tailpiece from sink is only 1inch before crossover tee then direct to trap.

You can reroute the entire drain, but the VENT must still come off above the trap, so you'll also need to plan on running the vent out the top and reconnecting to the vent in the wall as high up as possible, OK?

Otherwise, you could also build a deeper PTRAP using PVC 90s/street 90s... say 4" deeper as long as there won't be standing water in the sink... may allow you to install the branch tailpiece Milo posted a picture of.

More questions just let us know...

Mark

You can reroute the entire drain, but the VENT must still come off above the trap, so you'll also need to plan on running the vent out the top and reconnecting to the vent in the wall as high up as possible, OK?

Otherwise, you could also build a deeper PTRAP using PVC 90s/street 90s...say 4" deeper as long as there won't be standing water in the sink...may allow you to install the branch tailpiece Milo posted a picture of.

More questions just let us know...

Mark

Thank you Mark that is what I wanted to know. Basically I can make a loop by coming through the floor and the rehooking into existing for the vent. Correct?

Correct...

Is this a single compartment sink or a double? If double, you should be able to install the dishwasher drain wye in the horizontal section between the two compartments. You could also "turn" your trap around to gain enough space for the wye. Or, instead of bringing the drain up through the bottom of the cabinet, simpy open the wall and lower the drain stub out (gonna have to open the wall anyway to access the vent if you come up through the floor, so just lower the drain then.) Ive posted some pics (not the best pics, mind you (surprisingly hard to find pics of good plumbing on the web). Good luck and please let us know how things turn out.
Lee.

There is always room to insert Branch "T" under the sink to accommodated DW drain installation... Rerouting entire line is much (much) more work to do

Btw: In the post #8, Pic #2, that trap is installed backwards

I know the trap is installed backwards in pic #2, Milo. That was the point of the pic, to show another way of making this work without doing a complete re-do of the drain/vent. I know it is a hack way of doing things, but it does work when other options just don't add up. You can't honestly tell me you have never installed a trap backwards, can you?

Lee

Is this a single compartment sink or a double? If double, you should be able to install the dishwasher drain wye in the horizontal section between the two compartments. You could also "turn" your trap around to gain enough space for the wye. Or, instead of bringing the drain up through the bottom of the cabinet, simpy open the wall and lower the drain stub out (gonna have to open the wall anyway to access the vent if you come up through the floor, so just lower the drain then.) Ive posted some pics (not the best pics, mind you (surprisingly hard to find pics of good plumbing on the web). Good luck and please let us know how things turn out.
Lee.

This is a double sink and I just found out that it can be installed on the horizontal conector. Thanks for all your help everyone.

Re pic #2: If I ran into this situation than I would remove that deep Frankel sink strainer and used regular Spin-Grin type which would give me the needed space to insert Branch T.

Imc, Glad to hear it. Sure beats rerouting the complete drain.
Lee.

Milo, but in pic #1, it is a standard strainer and still not enough room. In pic #2, deep strainer with plenty of room when the trap is backwards. It looks to me like it is the same sink, cabinet, rough in, only they, for some reason, changed out the strainer and reversed the trap in the second pic. Go figure, a backwards trap sometimes saves the day, not to mention homeowners pocket book. Wouldn't you agree, Milo?
Lee.