I have a problem where if the basin is full and water is running there are drippings of water all along the bottom of the basin through a seam that meets the flat part of the base where the tailpiece connects. There is no water going into the overflow... so it's a mystery as to how the water is going somewhere other than inside the tailpiece. Covering this leak with plumber's putty wouldn't seem like the best fix... the water seems to be misplaced..

It sounds like the drain seal got ruptured. Remove the upper lip of the drain and clean off the old seal. Now take plumbers putty and make a small rope. Put it under the drain lip and tighten it until the excess putty squeezes out and the connection is tight. Now fill the bowl. Leak all gone? Let me know, Tom

When you say that the leak is "through a seam that meets the flat part of the base where the tailpiece connects" are you meaning "where the drain pipe meets the bottom of the basin"?

If so, then fill up the bowl and then turn the water off.

If you see the same leak, then the problem is with the connection between the drain and the bottom of the basin.

Do that test and let us know how it goes.

Thank you. You know... the more I thought about 'misplaced water'... I realized that the water must not be going directly down the drain... so yes, where the drain connects to the basin at the top, water must be going under that piece and into the inner liner between the basin and the exterior wall. I've never removed a tailpiece from a basin. Will it come apart easily? Any advice?

Let's nail it down.
If it leaks when the stopper's closed and there's water in the bowel you have a ruptured seal.
If it holds water and leaks when you drain it then the problem is in the connections under the sdink.
So which is it? Back to you, Tom

The stopper doesn't have to be closed in order for the basin to fill up when the water is on full force because of the tight clearance between the stopper and the lip with these fixture designs today. But, yes, that is when it leaks, when the bowl is full. I believe you are correct about the seal under that lip that is flush with the bowl. The leak is no where near the connections... they're all dry. So, when I remove the drain from the basin, is there any care or special tool I need in order to remove that decorative lip from the basin without marring the visible side of the bowl? Thanks for your help!

Is there any care or special tool I need in order to remove that decorative lip from the basin without marring the visible side of the bowl? Just a pair of large pliers. Loosen the nut directly under the bowl,(seem image) until you can lift the drain and get under the lip to clean out the old putty seal. Make a rope of putty and tighten the nut back down. Remove excess putty and test. Better now? Good luck, Tom

Thank you, speedball, for helping here. I see now that I was answering while you were.

Eric, listen to speedball: He is our chief plumbing expert and is 2nd to none.

OK, I've replaced the putty around the flange or drain lip. I now know that any water that goes through the overflow is going down the inside of the basin and leaking through a seam around the exterior base of basin. There are three other sinks in my home designed like this one and this is the only problem one. It is part of a double sink vanity. I see evidence of mold around the seam. It appears that there is a translucent caulk on the others covering this seam. My question is: if I use caulk over this seam will that fix the problem or redirect the water to another undesired area under the bowl. Is it possible to submit pictures to this site?

I would clean the mold off with bleach and caulk the seam with Silicon Jel.



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How do I add pictures and other file types to my post?
A. "Attach" files (including pictures) from your computer. This method puts the attached file below the text of the post.
Click on an Ask or Answer button to ask or answer a question
Compose your question or answer in the window.
Under the window where you composed your question or answer is a section called Additional Options.
Click on the Manage Attachments button: a pop-up dialog will open. NOTE: The Manage Attachments dialog lists the maximum sizes of the various types of files that may be attached.
Click the Browse button to navigate to the image on your computer and double click the file on your computer: this will return you to the dialog window.
Click the Upload button.
Click the link to close the dialog window OR repeat numbers 5 & 6 to attach another image.
B. "Embed" image(s) from the internet. This method inserts an image wherever you wish within the text of your post.
Click the Insert Image icon above the posting window: A pop-up asking for the URL will open.
Enter the URL of the image in the field then click the OK button.
Good luck, Tom