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Marc, Plumber
Category: Plumbing
Satisfied Customers: 1594
Experience:  Plumbing heating & home maintenance contractor
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Moldy odor coming from drain in bathroom sink. Ive put vinegar

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Moldy odor coming from drain in bathroom sink. I've put vinegar down overnight and in the AM with two cauldrons of boiling water -- no difference. I've plugged up the main drain, put in 1/2 gallon of bleach and then SLOWLY put the faucet on hot-drip, to intentionally make it overflow with the bleach mixture and drain out the overflow. Odor still persists. I've used very narrow brushes to clean out (nothing there anyway) the overflow line as well as the regular drain line. There is nothing "stuck" in the line, the water is draining perfectly. Any ideas?

Marc the plumber : Hello and thank you for using I will assist you today with your question to the best of my ability.
Marc the plumber : Most smells coming from bathroom sinks originate from the overflow in the sink. The fix is removing the sink and disconnecting the drain assembly from the bottom of the sink to clean the complete overflow from the top hole to the drain hole. Most of the time the smell is from the area where the drain connects to the sink as bacteria builds in the area where the plumber used plumbers putty.

I'm understandning what you're suggesting...but wouldn't those aeras in question be accessible to the flow of water passing them by? I'm tryign to do this on my own and cannot remove a sink and disconnect driains, etc. Think hard on there ANY other little likely thing that I can do that might work without dismantling the entire set up.

Marc the plumber : If you are able to plug the drain from below and allow the solution of bleach to sit into the lower drain area and overflow of the sink then you can eliminate the odor.
Marc the plumber : This can be done by removing the trap and using a rubber cap to plug the bottom of the tailpiece then filling the sink to include filling the overflow and allowing the solution to sit for a few hours.

Let me take another look at this, Anatomy 101 under the sink/drainage apparatus. Am I dismantling the "U" shaped pipe under my bathroom sink?

Marc the plumber : Yes from the drain of the sink tailpiece

Marc --


I don't have the tools or know-how to remove the workings under the sink. But before I venture into that wild world -- what about if I were to take a shop vac, but it on exhaust (block the small overflow in the sink basin) and let the hose rip. Wouldn't at least in theory blow anything in the line away? If now the shop vac, then how about a power washer. That's certainly powerful. Just askin'



Marc the plumber : Prepare to get the entire bathroom soaked with a power washer! A shop vac will not work. The only option is to remove the drain assembly from the sink and clean out the overflow tubes and holes.

Got it...more later.



Marc the plumber : Ok

I've removed everything and understand what I'm doing and why I'm doing it...but I don't have the proper tools. More later. No one's around -- they were all planning on the Belmont Triple Crown today.

Marc the plumber : Lol. Okay well I sincerely XXXXX XXXXX are as successful as you are!!

Wait -- there's more. You know I just NEVER give up easy. So in a blinding last effort I poured Oxy-Clean (peroxide) down the drain and added a huge pot of boiling water. Let's see. It drained beautifully -- the problem is not about drainage. It's about that odor.


Continuing, so I took a champagne cork and jammed it into the sink drainage hole. It if perfectly. I then took a mini cork and jammed that into the overflow drain -- so now there is NO odor, because there are no open drains. Seeing that I'm alone here anyway, when I have occasional to use that sink I'll just pop out the cork. Maybe by next weekend I can borrow the tools to do this job. Any OTHER ideas? Let me know. But remember -- there are not four teenage boys shaving over this sink. It's only me. I always have the little mesh add on strainer in the drain.



Marc the plumber : Haha. You are inventive for sure!! If you could figure out a way to plug the drain tailpiece (before it enters the trap) you could simply fill the sink and overflow and let it soak.

There is no last effort truth be told. I went to Home Depot. Bought a new Drano in a gel formulation. Pour in 1/2 bottle, wait 1/2 hour follow it up with a huge pot of nearly boiling water, heave-ho. Good. But this is not about drainage. I'm hoping that this will grab the offending plaque build-up and whisk it away. There's a real-life correlation with arterial build up. They should invent stents for plumbing lines. Anyway I just did this about 20 minutes ago. I'm closing the door and will await the diagnosis in the AM. I'm still looking at the shop vac. Why wouldn't that work? With the hose tightly affixed to the drain then power it up, vacuum out the already gummy material. I've used this same shop vac to remove wasp nests, etc. Worked great. Just another application.



Marc the plumber : The vacuum will not remove the debris and such that needs to get cleaned. It may get some but not all.
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