I am thinking of doing something like this, too. Here is a pic of something I found awhile back:

{{!gwi}}

I think the plumbing should be black pipe, though!

I believe we are under the UPC here in the Seattle area (actually Sammamish, just East of Seattle). I recall a post by lazypup some time ago that said an arrangement as pictured was not legal under the UPC but was under the IPC.

I want to do something similar, but use two separate fixture arms (drain lines) at different heights that will merge into one common vertical drain further downstream in the wall.

Hmm. I wonder why it wouldn't meet UPC - - anyone hazard a guess?

We are having problems, too, with our outflow from the garbage disposal. Is this the type of problem you are anticipating? Here is our set-up and why I am very interested in the answers to your questions, too.

{{!gwi}}

What you currently have is an amateur attempt to make a very simple task complicated. While it would pass code under the IRC it is without question, unsightly, unprofessional and way too complicated.

The reason that it does not pass under UPC is simple:

UPC-1001.1 only one rap permitted on a trap arm.

Under the UPC you could install a second trap arm in the manner you propose, however if you do so you must compute the load at 3dfu for each trap. Given that the UPC limits a 2" branch line to 6dfu's you may not have any other fixture attached to that line.

The simple solution is to begin by removing and discarding the factory supplied 1/4 bend on the disposal. You then get a "Disposal Type End Waste Kit" which will have a straight cross tube with a flanged end. The flanged end is attached directly to the disposal body where the factory supplied 1/4 bend is now. This will give you a horizontal cross tube at the same elevation as the disposal discharge port, approximately 4" higher than the current cross tube.

Attach the code required "Baffled Tee" to the end of the cross tube and the tailpiece from the second sink. The P-trap is then attached to the discharge end of the Baffled Tee. (See Attached Illustration.

Previously it was mentioned that the pipe should be black. That is not correct. The IRC & UPC both approve schedule 40 PVC (White Pipe) or ABS pipe (black pipe).

The slip joint type fittings I.E. End waste kit & P-trap are generally made of polyethylene or polypropelene and either type are fine.

Wonderful! Thank you lazypup, on behalf of all those in GardenWebworld who needed this! Simple, clean, and looks like it will improve the situation, at least for my problem! Thanks for also explaining that white and black piping are both OK.

Watch out for plastic baffled Ts.

The plastic is so thick that it creates a real clog point, especially on the output of a GD.

More than have the pipe bore is obstructed.

Metal baffle Ts have less blockage in the line.

Lazypup's Fig 2 is exactly like ours is currently connected, and the baffled plastic tee is EXACTLY our problem. It's very prone to clogging with certain types of food waste. Maybe some of that is the old disposal not doing its job completely and maybe the new heavy duty one will solve the problem... but I really would like to get rid of the baffled tee altogether.

I'd run the sink and disposal into a double wye and then into a p-trap, but that's not legal because there isn't any separation between the two where they meet. That's why I was thinking of separate fixture arms.

Each trap must be served by its own vent. You cannot use two traps on a single vent according to the UPC.

Tridogdude,

That statement is totally incorrect. You could in fact vent the entire bathroom group with one vent.