Corian Vanity Overflow Replacement

My bathroom has a model 816 Corian sink whose overflow has been smelly since the day I moved into this house. This model of sink, instead of having the overflow hose molded into the body like most ceramic sinks, instead uses an external hose to do the job. A plastic donut surrounds the popup’s overflow hole with a 20mm ID hose heading up to an hose elbow which is lightly glued into place.

This design always leaves some water in the donut and hose which over time stagnates and gets stinky. I replaced the stock silicone hose which got rid of the smell for a little while but it then of course came back. In the below photos you can see the clear vinyl hose I used.

My solution to this problem was to put a 1-1/4″ disposal wye tailpiece (LASCO 03-2841) into the sink’s outflow and to connect that its wye to the sink overflow. This is a smooth, simple design that leaves no standing water.

In addition to the disposal wye I needed to get a new popup drain, one without an overflow hole.

I couldn’t find a wye tailpiece with a flanged top that would attach directly to the popup drain so I used attached it the tailpiece included in the drain kit. I needed to cut both the disposal wye and tailpiece in order to get them to line up with the horizontal drain pipe.

So in summary here is the stack of parts:
* Popup drain (no overflow)
* Tailpiece (included with popup drain kit). This threads onto the popup with a nut.
* Disposal wye. This attaches to the tailpiece with a slip joint.
* P-Trap. This attaches to the disposal wye with a slip joint.


The hardest part about this project was adapting the hose sizes. The sink’s overflow adapter needs a 20mm ID hose while the disposal wye has a 5/8″ pipe. The local hardware store doesn’t carry that size hose barb adapter, unfortunately.

My solution, and it’s not a great one, was to use a 5/8″ hose x 1/2″ MIP (male pipe threads) plastic adapter for this job. The 5/8″ end connects a length of 5/8″ ID vinyl hose to the disposal wye while the 1/2″ pipe thread end just happens to nicely fit inside the 20mm hose for the sink. I gooped up the threads with silicone caulk and used a hose clamp so it should be watertight. Do note that this is not a pressurized system, just one that needs to contain the occasional splash of water.

I would have been better off using the Dearborn 817TB-1 which has a 7/8″ wye. That’s about 22mm which would have worked fine with the 20mm ID hose. The only negative about this product is that it does not include the slip nut and washer, but those are an inexpensive local purchase.

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