Plumbing Question

[rp2813]

My buddy has a double sink with disposer on one side.  The disposer sink backed up but curiously (to me, anyway) the other sink still drained fine, and that is the side that has the P-trap and connects to the sanitary line in the wall, everything being PVC.  It was easy to conclude that the clog was located in the horizontal section between the disposer and the vertical section from the regular sink, and it was easy to loosen the connections at both ends for inspection.  This is when I discovered an odd fitting I never knew existed, but certainly explained why the side without the disposer would still drain.

 

I've attached a couple of pictures.  The fitting that ties the horizontal section into the vertical above the P-trap is divided in half inside, which means both sides have their flow restricted when passing through this fitting just above the P-trap.  This may be OK for the side that just has a strainer, but it's problematic for free-flowing content that the disposer has processed.  This half-and-half fitting is where the clog was located. 

 

While I understand the logic of one sink that drains is better than two that don't, I'm wondering if this is proper when a disposer is involved.  The clog amounted about a tablespoon of muck.  With a full-width drain, it would have been dispersed. 

 

Since it's in an apartment, nothing can be done other than running a lot more water after using the disposer, but I'm curious about whether the pictured fitting is supposed to be used when a disposer is involved.

 

The photos have been turned on their side by the attaching mechanism here, and these are views of the vertical section.  You can see the flat piece that runs through the center of the fitting, forcing a hard 90 degree turn for waste from the disposer.

 

[eronie]

The divider is so the disposal doesn't come the other sink.

 

[mattl]

When I plumb in a disposer I always separate the 2nd bowl as much as possible from the disposer, but I've never seen a split fitting such as that.

 

 

Edit:  In thinking about it, that divided fitting looks like a clog point waiting to happen. I'd re-plumb to avoid that..

[this post was last edited: 7/19/2023-19:23]

 

[rp2813]

Total Clog Point!

Thanks Matt. That has been my experience too. I highly doubt that building codes would allow for using a divided pipe in a wall with back-to-back toilets on it, and doing so under a double sink with a disposer seems questionable.

 

I just took this picture of the junction under my own double sink. The lateral section coming from the right connects to the disposer. Notice the curved area where it dumps into the vertical pipe above the P-trap. I think this indicates that the flow from the disposer is unrestricted by the fitting.

 

I’m going to continue my online search for information on correct uses for divided fittings. I think they are not supposed to be used if a disposer is involved.

 

[rp2813]

OK, so far I've found the name for this fitting.  It's a "baffle tee" and I'm providing a link to a discussion about this very issue.  I couldn't believe that using a baffle tee for a disposer connection was being defended by plumbers' associations or whatever -- until I read the final post that said reducing a 1-1/2" pipe down to 3/4" for a disposal outlet is just asking for trouble, but it also offers easy money for plumbers who can clear the tiny clog in like five minutes.

 

I'll have to investigate what the local codes are for this arrangement.  It sounds like the plumbers unions have gotten as bad as the trial lawyers with regard to self-serving regulations.  I suppose I shouldn't be surprised.

https://www.plbg.com/forum/read.php?1,498863

 

[bradfordwhite]

Those have been around for decades. When I was a teen I installed one on our double sink/disposal situation and I too did think the baffle restricted things too much.

I took an unmounted hack saw blade and cut out as much of the baffle as I could. The first time I turned on the garbage disposal I found out why the baffle is needed. The force of the disposal shot water up out of the other sink drain several inches. Along with the water came all the gunk that was in the disposer. It was not pretty.

Separate traps for each sink, plus a trap for the dishwasher and any other appliances needing a drain like an R.O. filter, preferably going into a 2" drain line would be the best choice.

 

[combo52]

Double Kitchen Drain Connections

Hi Ralph, that T fitting is NOT supposed to be used with a disposer, there was a discussion about this on AW a few times and that was the consensus.

 

It should be replaced with an open T fitting or better yet a Y fitting like your kitchen sink has.

 

John 

 

[rp2813]

Thanks John.  I have a feeling it's a code violation since the 4-plex was built in 1961 and a few years ago the shady guy next door installed the current double sink and likely all of the PVC fittings under it. 

 

I called the building department to inquire about it, but I was transferred to public works (not the right place), then hit an unidentified voicemail box, so I hung up. 

 

The disposer developed a couple of leaks while the sink was backed up.   As many here might expect, it's an ISE Badger that has rusted out.  So, when the plumbers come to replace that, I'll be the one to let them inside to do the work.  I think it's likely that they'll want to remove the horizontal tube that feeds into the baffled fitting and will see the problem, but in case they don't, I'll advise them take a look.  The landlord just pays them for whatever the job requires without questioning it, so maybe I can seize this opportunity to facilitate correction of the problem.