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New bathroom countertop drain leak driving me nuts!

rws762's picture

New bathroom countertop drain leak driving me nuts! (post #212049)

I just installed a new bathroom vanity countertop (St Paul by Home Depot) and installed a new Moen faucet. I used plumbers putty to install the drain and the drain leaked. I took it apart and used more putty than the first time and I still see a leak coming  through between the nut and the threads. I didn't try silicone yet because I know it's a bear to clean up. Should I go the silicone route? If I do how long should i let it dry before testing everything? Should I apply silicone to parts other than around the underside of the waste seat? BTW the parts are all plastic and upon disassembly appear to be in good shape, I'm not sure what the sink is made of but I know it's some sort of man-made material. Any help would be greatly appreciated, thanks.

HI RWS, So you are seeing (post #212049, reply #1 of 10)

HI RWS, So you are seeing water leaking on the outside of the tailpiece up high?  If so, then water is definitely getting through under the flange of the tailpiece.  I would recommend either switching to a chrome (any metal) tailpeice and stick with putty.  If that doesn't work then silicone may be the only way.  How does the flange sit in the drain cutout when all is dry?  It should be tight.  In other words, you shouldn't have to crank the nut under the sink to deform the flange to fit the sink, BUT sometimes with the Home Depot stuff that's what you have to do and the plastic parts don't do that as well as metal.  Good luck, I know that is a frustrating problem.  It is a problem that rarely occurs when you work with higher end products, but is very common with the less expensive materials. 

New bathroom sink drain leak driving me nuts, please help! (post #212049, reply #2 of 10)

Yes I am seeing a leak come out between the bottom of the nut and the threads. If I do switch to silicone how long do I let it dry before testing, 3 hours as listed on the label?

It seems odd to me that (post #212049, reply #3 of 10)

It seems odd to me that plumbers putty, if applied in sufficient amounts, would allow any leakage, at least right off.

You do understand that you shouldn't be stingy with the stuff, right?  At least half of it should ooze out as you tighten the fitting.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

New bathroom sink drain leak driving me nuts, please help! (post #212049, reply #4 of 10)

Yes I am being very generous, probably as big around as my little finger, and yes probably half if it is oozing out as I tighten it, I just gave it another shot and even used teflon tape on the threads of the pipe and it still leaked from the same place, between the bottom of the threads and the nut. Arrgh!

If I'm understanding what (post #212049, reply #6 of 10)

If I'm understanding what you're saying, the nut is a compression nut, used to pull the pieces of the drain assembly together.  It should not get Teflon.  (In fact, I can't think of any scenario where a nut should get Teflon.  Teflon is only used where male and female pipe fittings are screwed together, and the nut is not a pipe fitting in that sense.)

The fact that the leak is from under the nut suggests that either you've assembled things in the wrong order or there's a crack in the tailpiece.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Note that a common source of (post #212049, reply #7 of 10)

Note that a common source of leaks in bathroom sinks is the overflow "ductwork".  Some sort of pipe or hose runs down from the hole in the front of the bowl to a sort of collar around the drain tailpiece.  The tailpiece needs to seal both at the top, where the drain opeing is, and at the bottom, below the overflow collar.  Plumber's putty (or a suitable gasket) is needed in both places.

Also, the tailpiece needs to be appropriate for the sink.  There are slots in the tailpiece that let water in from the overflow collar, and these slots need to be the correct size for the specific sink.  I think this is usually "standard", but there may be variations that would lead to incompatibility.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

be sure to... (post #212049, reply #5 of 10)

Be sure to check that the tailpiece or drain assembly don't have any defects or cracks. I got a new marble top put in place, installed a brand new Restoration Hardware way-too-expensive faucet, followed all the standard recommended practices, and was stymied for three days with a leak. I put on all manner of new gaskets and seals and flanges and redid the whole thing probably 5 times. I finally found that there was a tiny hairline crack on the brass tailpiece and water would come out when I did a test with draining a full bowl of water. RH sent me a new drain assembly and that install went without a hitch. All the cussing and putty wouldn't fix that. And silicone, in my opinion, is preventing a symptom not fixing the cause.

Some of the man made (post #212049, reply #8 of 10)

Some of the man made countertops and sinks  can have problems with water getting into voids inside the material they are made of then leaking out around the  drain. The leak doesn't come from poor installation but  from the material itself. You'll probably have to replace the countertop/sink to solve the problem.

Florida Licensed Building Contractor, 45 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

Drain Leak (post #212049, reply #9 of 10)

Teflon tape around tail piece threads that screws into the sink flange?