Asked on Sep 05, 2013

How to clean the overflow drain in a bathroom sink

Jennie Gaskin
by Jennie Gaskin
There has been a musty (moldy?) odor in the bathroom, and I've finally realized it is coming from the overflow drain in the sink. Because it was on hand, I've tried pouring bleach into the overflow. But the smell keeps coming back. It seems to be strongest there, maybe because it's a natural vent. I do know that this sink drains slowly despite using drain cleaner; we've planned to replace it for years but due to other circumstances it has been moved to the bottom of our list. Any suggestions on getting rid of the smell and hopefully the source of the smell?
  9 answers
  • Have you tried to take the pea trap off and clean it out that way? About once a year or less (depending upon draining and any smells) we removed our traps under the sinks and clean them out. You would be so shocked to see the gross hair (husband's side from shaving was way worse). Try that. To clean the trap is not hard but can be mess. Need a bucket to catch water but just use a pipe wrench or pliers that will fit around the nuts and twist off. Good luck.
  • Jennie Gaskin Jennie Gaskin on Sep 05, 2013
    Will remind my husband that it needs doing. He _does_ trim his beard over the sink and is not good about making sure all of it goes into the trashcan.
  • It's possible that there is no p-trap or it is not properly vented. Call a licensed plumber. It will be worth it.
  • Kevin Kevin on Apr 02, 2017

    I found an easy way to clean the "overspill" part of a bathroom sink. This is typically a hole near the top and inside the front of a bathroom sink. It is an integrated tube that leads to the main drain of the sink but is hidden. This typically gets mold build up over time. I use one of those spray bottles, the kind you can buy at HD or Lowes. Unscrew the pump sprayer, fill it with hot water, and put it over the hole at the top of the sink. Quickly squeeze the water out forcefully into the overfill hole. Be careful not to force too much too fast as it may make a mess. Use common sense and practice. The force of the water will dislodge mold and gunk and send it all down thru the tube and into the sink drain. Simply pouring water into this hole will NOT clean it thoroughly. Using the squeeze bottle and a sufficient quantity of water and force WILL dislodge most of the gunk. Do this a couple times. Typically I finish with a touch of bleach which I let sit a while. Then a final rinse. Quick and easy.

  • Misty Daugherty- Smith Misty Daugherty- Smith on Apr 02, 2017

    Have you taken out the drain stopper and cleaned it. Then take a1/4 cup of baking powder pour it in the drain and put some in the over flow hole then pour white vinegar in the sink and the over flow. It will start fizzing for a little while then take dawn liquid and clean sink and overflow then rinse well

  • Suellen Hintz Suellen Hintz on Apr 02, 2017

    Late some night put drain cleaner down the drain and let it sit overnight. The drain should be faster draining after this so water can't back up into the overflow. If not flowing significantly faster you'll need to repeat this another night. Wait a few days, then use kevin's idea to clean the overflow.

  • Pizzchzz Pizzchzz on Jul 12, 2018

    I think your sink is clogged. Some bacteria build up down the drain are responsible for the unpleasant smell. You can react baking soda and vinegar down the drain, and add hot water. For more on this, check out this post In this post, you will find other useful methods. I hope this helps. Thank you.

  • Jennie Gaskin Jennie Gaskin on Jul 12, 2018

    Thank you for your reply! I think we resolved the problem much like you suggested. It hasn't given us a problem since.

  • Taylor Sealy Taylor Sealy on Aug 20, 2019

    I have round overflow drain holes for the sinks and am just going to put rubber plugs in them. I don't fill the sink with water or leave the water running, so no danger of sink overflows anyway.