How To Fix Bathroom Sink Drain Leaks Underneath Gasket, Threads [SOLVED]

How To Fix Bathroom Sink Drain Leaks Underneath Gasket, Threads [SOLVED]

Is your bathroom sink leaking and you’t can’t figure out the source of the bathroom sink drain leaking? Today we show you how to fix a bathroom sink drain leaking underneath the sink where the black rubber drain gasket meets the bottom of the bathroom vanity sink basin, or drain pipe threads.

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This must be really frustrating for you when you install your new sink drain textbook perfect by the instructions yet still get the sink drain leaking underneath. You even installed the drain flange with silicone and still get the bathroom sink drain leaking from the drain gasket.

Don’t call the plumber, don’t pay for a needless and costly plumbing repair, you can fix the bathroom sink drain yourself, putting that drain leak behind you forever.

In this video we show you how to fix the bathroom sink drain that is leaking, so you can do it yourself. We show you three possible scenarios that can cause your bathroom vanity sink drain to be leaking underneath the sink basin at the threads or the bathroom sink drain could be leaking at the rubber drain gasket where it mates up to the bottom of the sink basin. You can also get leaks where the drain pipe meets the sink trap, or where the sink trap meets the street drain line. Lots of moving parts!

We also cover in detail whether your leaking drain repair should use or not use plumber’s putty to avoid staining the bathroom vanity sink. We’ll also cover Teflon tape (plumber’s tape), pipe dope sealant, and silicone to fix the bathroom sink drain.

Note about wrapping Teflon plumber’s tape for this repair:

The lower Teflon tape for the black drain gasket should be wrapped counter clockwise, to match the direction of the drain gasket screwing upward from underneath the leaking sink basin, and the upper Teflon tape should be wrapped clockwise around the threads of the leaking drain pipe to match the direction of the drain flange inside the sink, which will be screwing downward onto the pipe threads in a clockwise motion.

We also show you how to root cause this difficult plumbing repair and how to apply the Teflon tape onto the threaded drain tail pipe in your quest to finally fix the bathroom sink drain, and put an end to that drain leak once and for all. bathroom sink drain

After you fix your leaking sink drain pipe threads, you have to perform thorough water leak tests to make sure water is not dripping inside your vanity via a sink leaking water down the drain pipe. Don’t just turn on the water for a few seconds and think that you have fixed the bathroom sink drain.

Now you have to test for a leaking vanity drain.

You still have to fill up the sink basin with water until the water starts to drain out through the overflow hole, and then you also need to let the water suddenly all drain out. You have been moving a lot of parts underneath your bathroom vanity sink, so make sure to test for the sink trap leaking as well. Sometimes if the sink trap is leaking, we add pipe thread sealant to the leaking trap connection.

Causes of your bathroom sink drain leaking underneath

One common drain installation mistake is when DIY folks fail to make sure the drain flange is screwed all the way down onto the drain pipe threads, and end up with a leaking vanity drain. Water then seeps through the crack between the flange and the pipe and leaks down onto the drain pipe threads or over the rubber gasket.

Another failure mode causing a bathroom sink drain leak and plumbing repair if the drain hole underneath the sink basin has imperfections that prevent the gasket from mating up to the sink and making a perfect seal.

So now you have a bathroom sink leaking from underneath the drain because the rubber drain gasket underneath the basin cannot fill all the imperfections along the rim of the sink’s flawed drain hole opening.

How to solve bathroom sink drain leaking from threads

We have also seen people seem to have issues with installing new Moen faucet systems with the Moen drains and they have a leak. The same can happen with Glacier Bay as well, because the leaking vanity drain is allowing water to leak down the threads of the drain pipe underneath the vanity sink. So that is another root cause of your bathroom sink leaking from the drain gasket.

The drain repair solution for this vanity sink leaking issue is simply to wrap plumber’s tape around the top of the pipe threads where the drain flange will screw on, and on the pipe threads where the rubber drain gasket will screw on to mate up to the bottom of the basin underneath inside the vanity.

We’ve come to the end of our bathroom sink repair

That completes this drain repair, and hopefully you’ll use the tips from this video to put a stop to your bathroom sink drain leaking water everywhere into your vanity below.



Scott Pace says:

Thanks for your video, it rocks. I struggled for a while until I found your video and started wrapping tape around the threads. Problem solved

John Scheuplein says:

I'm going to tell the manufacturer to recomend your video! What a nightmare I've been going through! I have the unit you used for this video and the instructions are lacking in detail for this supposedly easy install. I will post my results! Thanks again!

Flash Gordon says:

Jeff, perfect way to explain our situation! I just subscribed.

eureka K says:

Great 👍 video ,Thank you!

Jim Weishaupt says:

You put the Teflon on in the wrong direction. It goes clockwise if your are holding the threaded fitting on the left.

Ekklesia Blacksburg says:

So, I take it that the black plastic of the drain is not the black plastic that is warned against on the bottle of the plumbers putty?

matt125xp says:

Really appreciate it. You fixed my leak. Thanks Man!

David Croft says:

Excellant tutorial. Learned a great deal by watching you. Thank you.

Travis k says:

Shouldn't you have put the teflon tape up top on the same direction that you tighten the fitting? You did the exact opposite of what you said to do on the upper section.

jeffostroff says:

What plumbers tricks have you used to solve your leaking bathroom sink drain? Let us know in the comments below, and also post your questions you might have as you repair your leaking drain.

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