I have recently had a Corian bath counter top with integrated sink installed. The sink has an exterior overflow manufactured by Dupont. The overflow device looks like a plastic donut with a plactic tube that extends to the overflow opening in the sink. According to the instructions, the overflow assembly is designed for use with Corian lavatories. The 'donut' is 3 inches in diameter and approx 1.5 inches high. Based on the drawing that came with the overflow (no written instructions included) it appears the 'donut' portion of the overflow device attaches directly to the underneath of the sink bowl. The 'donut' has a thin black gasket on one side which I presume is the side that attaches to the sink. My problem: After following the drain instruction very carefully and using a generous amount of silicone caulk, there is a leak that is evident on the threads of the drain extension near the knuckle. The gasket that came with the sink (Moen- Banbury Model #: CA84913) was installed with tapered end in the 'donut.' I have asked local plumbers and they are not familiar with this device. Any recommendations on how to install without leaks? I have a drawing of the assembly instructions that I would be glad to fax. Thanks.

Photo would be great help...

Have to respond to this because I had a similar difficulty and worked it out. Forgive the long response but this was frustrating. First, after paying $1300+ for a custom corian countertop with integral sink I was not really pleased with they left a bag of overflow hardware with no information. Don't get me wrong, the countertop is beautiful and looks great. But the installers left the bag and said 'the plumber will know what to do'.

I'm very handy but I am not a professional plumber that is for sure. So I called the distributor (I Live in the greater Chicago land area so hopefully I would like to think they are professional here since the product is from Dupont, which no small organization!). I asked for an assembly diagram or any sort of literature that illustrated how the overflow assembly goes together. The lady said no such document existed and I was persistent stating I could not believe that such a nice product did not have any sort of document pertaining to this! Finally I got a hold of the manager and after a couple of conversations he called back and said 'there is a document!'. He faxed it and here is what I learned since. (I looked at the Dupont website and could find nothing so he did some legwork).

See the attached document they sent I put it in Word 97 format, that is what the distributor sent. The plastic overflow pipe that was included was RIGID and had 90 degree bend; does not resemble the diagram at all, does it? Furthermore, the compression gasket included in the overflow compression nut was installed backwards from the factory.

One of the tricky parts is that the straight linear part of the pipe that fits into the compression fitting on the drain assembly winds up being EXTREMELY short (not a good application for a compression fitting, by definition is it?). Therefore the cuts need to be very accurate, but how can you cut down the overflow pipe before the Dupont provided donut and gasket are installed on the bottom of the sink? And by the time that is installed you have silicon setting up in the drain so that’s pretty difficult. ALSO the overflow drain inlet at the top of the sink is OFFSET from the drain center. This makes aligning a SHORT compression fitting at the drain assembly VERY DIFFICULT. Now this short piece of rigid pipe requires the overflow threaded tap to be at a different angle than the pop-up drain tap for the faucet! So beware that your pop-up drain fitting could be a different angle than the overflow fitting. At this point I am wondering if the countertop installer provided the correct overflow kit.

But after several attempts I got it assembled with no leaks. I find it very disappointing that the most difficult part of my master bath remodel project was this overflow on an expensive custom Corian Dupont integral sink overflow assembly.

So please see the attached pictures to understand what the final installation could look like with a corian overflow and drain with pop-up. Take your time if you do it yourself.

This PC won't let me manager attachments let me try another to upload docs and pics.

KEYWORDS OVERFLOW ASSEMBLY - CORIAN LAVATORIES leak installation issues