How to Clean a Bathroom Sink Overflow Hole

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The job of an overflow hole is to prevent flooding in your sink. The sink overflow hole does it by diverting the water pressure to give you more reacting time.

It is an important invention to help prevent the spilling of water or contents within the sink from spilling out. You can any time face plumbing issues.

Therefore, it is your job to ensure that the sink overflow hole doesn’t get blocked. If the overflow hole is blocked, then it won’t be able to do its job of preventing the sink floods proficiently.

How to Clean a Bathroom Sink Overflow Hole

The bathroom sink overflow has the property to prevent your bathroom from experiencing spillage or flooding hassle. But in the meanwhile, it needs cleaning approaches as well.

Bathroom acrylic sink with shiny faucet

It is because bathrooms are hot & damp places, and such an environment is apt for mold & mildew to grow. The overflow holes are also favorable regions for mold & mildew!

Therefore, you need to learn how to clean a bathroom sink overflow hole. And this guide will help you with it.

Method 1: Keep the Overflow Hole Free From Debris & Blockage

Step 1: Make Arrangements for the Supplies

You will need some supplies in order to approach for the cleaning of your bathroom sink overflow hole. The supplies include:

  1. You will need a brush that is especially for cleaning the hole. You can also go for the pipe cleaners!
  2. A silicone-made funnel would be great for the purpose. Silicon material is preferable because it has the capabilities to withstand boiling water temperature. Also, silicon doesn’t conduct heat so easily, for which its funnels will be best for the purpose.
  3. You will need boiling water around 2 to 3 quarts.

Step 2: Process of Removing Gunk & Build-Ups From Overflow Hole

  1. You need to stick the brush or pipe cleaner inside the hole.
  2. Now, push and pull that brush in a repetitive motion for few times. It is to remove as much build-up and gunk as possible from the overflow hole.
  3. In the meanwhile, place your container of water to boil over the gas.
  4. Place the silicone funnel into the overflow hole after you take out as much gunk or build-up as possible with the brush or pipe cleaner.
  5. Now, you need to maintain a slow-motion while pouring the boiling water through that funnel.
  6. It is to flush out any of the build-up remnants. Make sure you are using gloves here, as you would not want to burn your hands with the boiling water or its steam.
  7. Repeat the process a couple of times if it seems necessary. If you wish to be sure about clearing the pathway of that overflow hole, then it is better to go for 2 to 3 rounds of boiling water pouring.
Clean bathroom white acrylic sink hole

Method 2: Remove Stinking Problem From Bathroom Sink Overflow Hole

If your bathroom sink overflow hole has a problem related to mildew or mold build-up, then stinking might be one of the many problems. Decay can leave behind a very pathetic smell that will ruin the entire bathroom space.

But if you follow ‘method 1’ in periodic intervals, then your bathroom sink will never be that stinky ever. And if it does, then here are the steps that will help you tackle the situation:

Step 1: Arrange the Supplies

It is always the first step for any cleaning approach. The supplies that you will need in order to eradicate the mildew stink from the bathroom sink overflow hole are:

  • Baking soda (1 cup)
  • White vinegar (1 cup & distilled)
  • Boiling water (2 quarts)
  • Silicone funnel to withstand the boiling water temperature

Step 2: Process of Eradicating Stink From Sink Overflow Hole

  1. In this step, you need to directly place the funnel in the overflow hole of the bathroom sink.
  2. Now, pour baking soda (1 cup) through that funnel.
  3. After that, you need to pour vinegar solution into the same funnel slowly. You might experience a fizz rising through the funnel as vinegar mixes with the baking soda.
  4. Now, let this solution that has passed through the funnel into your sink overflow hole settle down for around 15 minutes. It will help the vinegar and baking soda to activate their deodorizing attributes.
  5. In the next step, you will need the boiling water (2 quarts) for flushing the sink. Do it through the funnel but at a slow pace.
  6. You would not want to hurt or burn yourself with that hot boiling water. Therefore, you need to wear gloves before you approach this step.
  7. If you still sense the foul odor, then you just have to repeat the process and let the vinegar & baking soda settle down for a little more time.

Method 3: Clean the Sink Overflow Hole With Zip Tie

The bathroom sink overflow holes are very small or tiny. And if you don’t have an apt brush for cleaning, then it might be challenging to find a similar alternative.

Therefore, a long zip tie made up of plastic will help with the cleaning of the sink overflow hole without a brush.

Zip Tie as an Alternative Cleaning for the Sink Overflow Hole:

The zip tie is used in different ways and has a bending potential to curve around the channel of the overflow hole. When you push it down the hole, the rigidness of this plastic zip tie will push out the blockages.

It is better for the house owners to use a long zip tie in order to push it extremely deep into the hole’s channel. You can move the zip tie around to remove build-ups on the sides as well.

Therefore, it is one of the best alternatives or first-priority choices for cleaning the bathroom sink overflow holes. Following the zip tie clean-up, you can then use a silicone funnel and boiling water to flush the overflow hole and clear out the loosened debris and blockages.

Rubber garden hose on roll

Method 4: Clean the Overflow Hole With Rubber Hose

For executing this method, you will need a rubber hose or a dishwasher hose. They are also ideal tools to help you clean the bathroom sink overflow hole. Using these tools, you will eventually be able to break down any substantial build-up.

The steps for the same are as follows:

  1. First, you need to fill your bathroom sink with water. Keep the flow of water slightly above the hole for overflow prevention.
  2. You need to place one end of the rubber hose on the overflow hole’s opening.
  3. Now, you need to blow puffs from the other end of the hose towards the one at the hole’s end.
  4. Then drain the sink, and after it, continue blowing air into that hose again.
  5. Now, you have to repeat the process until the air you blow passes through the overflow hole’s channel freely.

Method 5: Clean the Bathroom Sink Overflow Hole With Bleach

  1. Prepare a liquid cleaner solution by mixing water and bleach.
  2. Pour down the cleaner solution through the overflow hole.
  3. Let the solution settle down for few minutes.
  4. Now, use boiled water and a silicone funnel to flush the sink and solution.
  5. Repeat the process if you still find your overflow hole working inappropriately.
  6. You can also go ahead with any ready-made commercial liquid cleaner for cleaning your bathroom sink overflow hole.

Here is a detailed video that has narrated the steps visually. It will help you with a better cleaning approach!

Close-Up shot of PVC pipe with flowing water

Frequently Asked Questions

Will the Use of Vinegar for Cleaning the Bathroom Sink Overflow Hole Damage the PVC Pipes?

Even though the vinegar solution is acidic, it does not have any adverse impact on the PVC pipes.

Therefore, vinegar will not hurt the PVC pipes’ quality for cleaning the overflow hole of the bathroom sink. It has no such properties to generate heat inside the PVC pipes. In fact, there are certain chemical cleaners that do melt the pipes, but not vinegar!

Do the Bathroom Sinks Mandatorily Need an Overflow Hole?

There is no such mandate for the bathroom sinks to have overflow holes. But, the purpose of having an overflow hole is not just to prevent flooding by diverting water back to the drain. In fact, it also improves the speed of drainage.

Therefore, you should consider adding an overflow valve and hole to your bathroom sink for your running faucet conditions. It will buy you some time to act upon fixing the condition.


Bathroom sink overflow holes are often ignored. You definitely clean your sink from the outside. But the build-up on the inside is something that will create more significant problems in the long run. Therefore, the cleaning of overflow holes should not be at the time when a problem arises.

Allen Michael is the Founder and Editor of Home Viable, a website that he started to provide readers with tips on home efficiency and automation. He draws on his engineering background combined with his family-of-four experiences for his articles.