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Thread: Mildew smell coming from overflow holes

  1. #1

    Default Mildew smell coming from overflow holes

    I have a Kohler pedestal sink in my bathroom and it has 3 overflow holes in the back. I have had the sink for 4 years and all of a sudden (last few months) my husband and I have noticed a very strong mold/mildew odor coming from sink when the water is running. We took it off the wall and cleaned out the pipes and replaced the gasket but a week after we installed it, the odor is back. Now I squirt bleach into the overflow holes which eliminates the odor for about a week, but then it comes back. Any ideas on how to eliminate this odor once a for all? The odor isn't coming from the drain it is coming from the 3 overflow holes. Thanks

  2. #2


    Your overflow may be somewhat blocked, which is causing water to pool up and create mildew. That is why squirting bleach only temporarily cures the problem. If the blockage is organic, for example, soap scum, hair, etc., you should be able to break it up and flush it out with a huge amount of bleach or a small amount of liquid plumber. If the problem is due to a buildup of mineral deposits, you can try squirting a lot of vinegar down there. I'm not sure what to do if the blockage is caused by a toothpaste cap, etc...
    Last edited by Verdeboy; 10-11-2006 at 09:29 PM.

  3. #3
    Plumber Cass's Avatar
    Join Date
    Nov 2005


    To clean it right the pop up would have to be removed and then you may / should be able to get a bottle brush up into the cavity from the pop-up area and clean it out. You should remove the sink to do this.

  4. #4
    Master Plumber master plumber mark's Avatar
    Join Date
    Feb 2005
    indianapolis indiana - land of the free, home of the brave....
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    Talking bleach and bakeing sode

    try bleach and then bakeing soda down those holes...

    bleach will kill everything dead, dead, dead....

    and the smell should go away.

  5. #5


    I had the same prob as you. My builder (won't call him a plumber) put too much plumbers putty around the pop up when setting, and it oozed down into the overflow drain holes.

    Remove the popup so you can see the drain holes. If they're obstructed, remove the drain and re-set it.

    Good luck removing the popup. It's a PITA once the sink's been set (unless yr a pro - me not).

    Alternatively, you might be able to snake it from the overflow holes w some long pipe cleaners.
    (important note: I'm not a pro)

  6. #6


    Quote Originally Posted by prashster
    Alternatively, you might be able to snake it from the overflow holes w some long pipe cleaners.
    Pipe cleaners is a darn good idea. They also make a very thin bristle brush for very narrow mouth bottles that might even work better. The cleaning surface is somewhat bigger than a pipe cleaner and it is longer.


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