Mad Mike
Well-known member
It's likely wrong. The second capped pipe is almost certainly a vent. After you clear the clog, fill the sink as high as possible, remove the drain plug and time how long it takes to empty - if you hear gurgling (like when you pour a gas can without opening the vent), the line isn't properly vented. Fill the sink again, this time remove the cap on the pipe to the left. If it drains a lot faster and doesn't guggle -- that second line is your vent.@Hardwrkr13 I am with many others here that it does not look correct but that doesn't mean it is entirely wrong depending on what is under the floor. Being an island, maybe there is a trap hidden in the floor with venting??? That second capped drain pipe is also an oddity.
An inspection camera may be your nest friend here, a look down beside the drain pipe(s) via the existing holes in the bottom of the cabinets and/or down the drain pipes. They can come pretty cheap these days, specially the USB ones that use your phone, depending on where you are someone here may also be able to help you out with theirs. I don't use mine often but when I do it is very handy to have.
To check for a Ptrap, use a 4" hole saw and punch thru behind the existing pipes. That's enough access to feel around for a PTRAP. use the cutout to repair the inspection hole.
No PTRAP found? Do this:

You will need: (
1 x Ptrap Adapter, 1-1/2" (this connects the drain to the filter basket tail piece)
1-1/2 - 1/2" ABS dishwasher tee (not shown in pic, install under Ptrap adapter over the PTRAP )
1 x union type Ptrap, 1-1/2" (the ones that unscrew in the middle) .
2' of 1-1/2" ABS (2' or so)
1 x 1-1/2" TY ABS fitting (this is where the Ptrap dumps into the drain and the vent connects vertically.)
1 x 1-1/2" 45 ABS fitting (female-female)
1 x 1-1/2" 45 ABS street fitting (female-male, fits into the bottom of TY fitting
1 x AAV (air attmittace valve -- be sure it's CSA approved, the $10 units don't always meet code- they risk flooding.
You'll need a small can of ABS glue and a bit of Teflon tape for the AAV threads.
You can cut ABS with a chopsaw if you don't have an ABS cutter and reamer, jusr be sure to debur the cut edges of the pipe using a knife or 80 grit sandpaper.
Dryfit everything before gluing.
Hope this heps.
