Kitchen sink drain and trap

shawnkey · Sep 11, 2007

I recently rennovated my kitchen, including the plumbing service and sink. I've now reinstalled the sink, garbage disposal, and the P-trap.

My question pertains to the level of the drains from the sink and disposal relative to the P-trap. I'll try to describe the setup:

From the wall, the 2" drain curves downward to connect to the standard P-trap. The P-trap, of course, curves upward and sits ready to accept the tee that joins the sink and disposal.

As a result of the new sink, which is lower than the original and has off-center drains, the tee is 1" to 2" LOWER than the mouth of the P-trap.

I assume that since gravity is the force that makes this setup work effectively, I must LOWER the P-trap to meet the tee. Is this correct?

Geniescience · Sep 11, 2007

yes, gravity will only work if water can flow downwards (along an almost flat line) to the P trap.

The Tee you mention is before the P trap, connecting two things both leading into the P trap. Your statement about the pipe coming out of the P trap and going into the wall is not well written, or else it shows there is a big problem.

shawnkey said:
... 2" drain curves downward to connect to the standard P-trap. ...

From the wall to the P trap, or from the P trap to wall, which way is up or down, and by how much? Gravity works there too, and water needs to drain out of the P trap.

david

Sponsor · 2022-01-29T12:20:58-0800

shawnkey · Sep 11, 2007

Diagram of setup

I have attached a picture that approximately represents the setup.

In the diagram where you see slip nut (just below the wrench), there's a 90 degree elbow that connects to the tee.

Is this setup problematic?

Jadnashua · Sep 11, 2007

As long as the leg going into the wall doesn't have to have a fitting in it that makes it try to go uphill, it is fine. If you'll notice, the inlet to the P-trap is higher than the outlet. You can't have the outlet trying to go up any further than that final bend to make it horizontal.

Patrick88 · Sep 11, 2007

you need to make the tee shorter in one way or another.

I assume you have a tail piece coming off the basket strainer, and the 90 fitting off the disposer. if you cut these to make them shorter will that give you the room you need.

hj · Sep 12, 2007

drain

We would have to see a picture of the tee. Many disposers are connected in a less than optimum manner which places the tee lower than necessary. If this is not the case, in your situation, then the only solution is to lower the pipe.

GrumpyPlumber · Sep 12, 2007

I agree with the above statement, without pics we're grabbing at straws.
The drain coming out of the wall is supposed to be between 12" & 15" high for a garbage disposal to work.
Also, the terminology Shawn uses is a bit confusing, "curve" implies there's a radial/circular shape to the pipe, what I think he means is "pitch", unsure of what direction the "pitch" is going when he says:
"From the wall, the 2" drain curves downward to connect to the standard P-trap."
The drains pitch should go up from the wall, down from the P-trap.

shawnkey · Sep 14, 2007

I have attached a pic of the drain setup. Notice that the drain in the wall IS higher than the inlet to the trap.

The drains in the sink are closer to the rear than the original sink, and the basins are different sizes (the one on the left is deeper and therefore lower). All this has created the somewhat jumbled setup that I have rigged in order to have water service.

I'm certain that you can guess what my story of woe is at this point. While I've fixed all the leaks, there is not enough gravity to pull the water out of the drain. Water stands just below the drain fitting in the basin on the left.

WHAT SHOULD I DO!?

Geniescience · Sep 14, 2007

funny! weird! no good.

right you are, this is a bad way for drain pipes to be.

david

Patrick88 · Sep 14, 2007

Your kitchen sink was never plumbed for a disposer let alone one of those new deep sinks, and new sink w/disposer way off. Wow

The only way to fix that is to open the wall and re pipe the drain.

There is nothing right about it. Looks like you have water sitting in the bottom of the disposer all the time. Thats not good probably rot it real fast.

Markts30 · Sep 14, 2007

Cut open the wall and drop the waste inlet tee a foot...
That should give you enough room to pipe the wink properly...

GrumpyPlumber · Sep 14, 2007

ahhhh, now I understand the reference to "curve".
That corrugated drainage is a no-no...all the above responses are correct...you're gonna have to open the wall and drop the tee-wye inside.
The way the drain is set up, you have a trap all the way up to the wall, in other words there's constant water inside that piping & partly in the diosposal as well.
I bet money the bottom of the inside of the cabinet is a wreck from water damage.

Cwhyu2 · Sep 14, 2007

Couldnt he put an extention from the trap crown and make the trap seal
4" instead 2"?

Patrick88 · Sep 14, 2007

cwhyu2 said:
Couldnt he put an extention from the trap crown and make the trap seal
4" instead 2"?

that would not be in code. it would also keep water in the disposer rotting it. plus would cause the drain to clog probably often.

Cwhyu2 · Sep 14, 2007

Your right pat what was I thinking

hj · Sep 14, 2007

drain

Not only is the water just below the drain on the left side, but the disposer must be full of water all the time, which must make a horrendous vibration when the disposer is run. There is no way to correct that kludge except to lower the pipe in the wall.

GrumpyPlumber · Sep 14, 2007

Other note,
Kitchen stubs are universally set at 12"-15" height off the finish floor for THIS reason.
Fire the plumber that roughed that.

shawnkey · Sep 15, 2007

Thanks for all your help!

So today is d-day, as in demolition. Given your advice, I'm going to tear out the wall and cut off the drain by about 12"--or a length that will put the outlet lower than the inlet. What kills me is my ignorance: just a few months ago, I had the perfect opportunity to lower the pipe and appropriately prep the plumbing before I rebuilt everything in the kitchen. I did not have the foresight I needed to keep me from traveling down this road.

To answer a few of your comments:

This setup was original to the house when I bought it a few years ago. My recent addition of the much deeper sink may have pushed the inlet a LITTLE lower, but the difference is only nominal. The curious thing is that I have had NO problems with ANYTHING up to this point. There's no water damage, the drains have drained, and the disposal disposed with no vibrations or apparent problems.

As I begin to contemplate how to reconstruct the remodel, I have a few questions:

When I cut the drain pipe in the wall, what should I use to connect the elbow that becomes the outlet port? I assume that a rubber collar will work?

Can I use schedule 40 to plumb everything? It seems that this more rigid route would keep me from chasing leaks.

hj · Sep 15, 2007

drain

1. The plumber who did this is probably already being "fired" or at least shoveling coal in the Nether regions.
2. If the connection in the wall is an elbow then you have a bigger problem because you have to go all the way to where the tee is and lower the tee.
3. If you do not know how to make the connection, call a plumber or you might end up with something just as bad as what you have now.

shawnkey · Sep 16, 2007

Success!

After much grumbling (from the prescription that I had to tear out the newly finished drywall), I grabbed the reciprocating saw and bit the bullet. I followed everyone's advice, from contacting a local plumber to lowering the outlet.

ÃVIOLA! The water drains with cyclinic force now, and I sleep well at night, reassured that everything is not rotting away due to sitting water.

Thanks again for everyone's time and advice.

shawn

Kitchen sink drain and trap

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