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picture of sink drain

I'm trying to stop this setup from leaking and improve the drainage. The sink is a bit low, and the basket strainer drops a few inches. Below that, I have a tailpiece with a dishwasher connection, and a horizontal waste line followed by an elbow into what is called a NY Trap.

The issues are that:
a) the horizontal piece seems to leak -- possibly fro the right side compression fitting, and from the tailpiece-horizontal connection. b) the horizontal piece actually has a negative slope. This causes it to be something like a second p trap , and when full, the water seems to back up a bit into the sink until the air bubble gets out. This seems like it would increase the chances of having leaks.

I haven't been able to find a good way to plumb this -- only tailpieces with dishwasher attachements are too long to make the next pipe go horizontal. Also can't seem to get a good seal between the tailpiece and the horizontal piece.

What should I do to stop the leaks? (Note: water in tub was there from before -- previous horizontal piece corroded so badly that it actually started leaking at the turn.)

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If you reconfigure so that the trap connects directly to the tailpiece you'll have all the height you need. In fact, you'll need a tailpiece extension (or new, longer tailpiece).

Clean up all the compression fittings and snug them up. If they're aligned as nature intended and haven't been damaged too much by being cockeyed, they'll hold water.

You could consider swapping everything for equivalent plastic parts. They, along with their nylon washers, may be easier to get to seal.

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  • 1
    I like this (my first thought was a shorter tail piece and a longer horizontal piece to get a non cockeyed connection) perhaps you could address that moving the trap will mean that they will need to deal with the angle, or a turn, to get from the trap to the SanTee at the wall. Sometime the red rubber washers seal better then the nylon ones in finicky situations.
    – Alaska Man
    Oct 8 '20 at 18:42
  • The fact that the trap can swivel 360 degrees usually makes it pretty easy to hit the right angles, so all that's necessary is length adjustments for the horizontal run(s). What did you have in mind?
    – isherwood
    Oct 8 '20 at 19:04
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    "The fact that the trap can swivel 360 degrees usually makes it pretty easy to hit the right angles" Usually yes; That is true if the santee is not farther away from the drain basket horizontally then the width of the trap. In this case it appears that if the trap on the tailpiece was at a complete 90 degree's it would still not have a straight shot from the output of the trap to the santee. That leaves some an angle to deal with. A 22.5 or a 45 (plus adapter) on the santee perhaps.
    – Alaska Man
    Oct 8 '20 at 21:27
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try setting it up like this. you will have to trim the dishwasher feed tail pipe a bit (be sure to bring it up high like @DMoores pictures to keep the sink from draining into the dishwasher. enter image description here

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  • That 'old trap' is only around 8-10 years old, and is a so-called 'NY Trap' I haven't figured out why they are required by code, but I saw a box of them at the big orange store the other day.
    – gbronner
    Oct 8 '20 at 22:19
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    @Alaska Man, an upside-down tailpiece will mate to the 1 1/2" threaded trap inlet, same as a basket strainer outlet. I've done it. I use an old-school flat reinforced-rubber tailpiece washer (as opposed to a "tophat" plastic one) when I do that though. Oct 9 '20 at 0:10
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    Anyway. Nice edit.
    – Strawberry
    Oct 9 '20 at 15:36
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Honestly if you want to do this right you need to completely change your start and finish. The start I would highly suggest with installing a garbage disposal. Dishwasher into garbage disposal, go straight out pvc and into p trap (pvc), out to wall pvc, and then the appropriate connector into wall (example connector). There are also disposals made for sinks with less height - I don't think yours really meets that criteria though so you probably don't need to pay more.

With a decent garbage disposal you are looking at about $125ish and it is done right - whatever metal you have in the wall has very little chance of having long-term issues (given you have a disposal and use it properly).

enter image description here

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