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Black Gunk in Sink Drain: How to Get Rid of Them?

Sink is a place where we all go near many times in a day. Much dirt and debris fell down the sink drain. And those dirt are very small. Which is why sometimes you will notice black gunk forming in the sink. It can be a nuisance and should be cleared up quickly. 

What is the thick black gunk in my sink drain?

If you work around the sink you will notice some black gunk like elements gather in the sink drains. These are the build ups of the residue of various dirt and things that go down the sink on a regular basis. Shaving cream, small hair, scum from soap, residue of the liquid soaps etc. 

If the sink has not been cleared in a long time it is common for some black gunk to form. It is basically all the residue or left over of the dirt that could not go down the sink. If you don’t clean the sink often, it happens.

What causes black gunk in the kitchen sink drain or bathroom sink drain?

Black gunk is usually a buildup of all the debris and residue of everything that could not go down the drain. Hair, scrums of soap, skin cells, shaving cream and everything that goes down the sink leaves residue and bacteria builds on them. And that build up bacteria creates the black gunk you see.

The sink is one of the most used places in any household. You will notice that everyone in the house uses the sink multiple times a day. Which is why the chances of the sink having unfamiliar materials is very common. And a common element is a black gunk in the sink drain.

This common black gunk can come from many things. The main reason behind it is the buildup of bacteria. But how the bacteria form and on what is something you should know. There might be other reasons as well. Given are the lists of reasons behind the black gunk forming in sinks –

Buildup of bacteria:

When there is some residue of skin or hair let behind the sink then there is a chance of bacteria building up on them. And this is very common as the chances of left over skin and hair being left behind inside the sink drain. 

Bacteria build up on them with time which creates a black gunk. 

Dirt and debris:

Sometimes debris and dirt get stuck on the outside of the sink drain. And it keeps building up if the sink is not cleaned frequently. That is when a black gunk-like material starts to form. The dirt may come from anywhere. 

It is usually the leftovers from the various items used in front of the sink.

Soap, lotion etc:

Soap scum and toothpaste grit are some of the common things that are left along the sinks. If you look carefully you will notice the left over of these items will create a black gunk. This will not be hard to clean but it does get stuck if left unattended for too long. 

The black gunk you see in the sink or in the sink drain is the result of debris or bacteria.

How to get rid of black gunk in the sink drain?

Black gunk in the sink is a very common and recurring problem that almost all homeowners have to face. The buildup of bacteria and gunk is the main reason behind these gunk forming. The solution to this problem may seem very simple. But there are many other options as well.

Don’t let any dirt, debris or leftovers buildup: 

The easiest solution to this issue is to not let any dirt, debris or leftovers buildup. This may sound like an easy task. But it requires constant cleaning of the sink. You will have to make sure that there is no visible leftover on the sink. 

And you will have to clean the sink drains regularly as well.

Cleared up immediately: 

If you notice black gunk already there in the sink you should get it cleared up immediately. A very easy way to get this job done in a matter of time is given below –

Water and baking soda:

You will only need water and baking soda for this. And first you should boil the water and make sure it is hot. 

Mix them well:

Add the baking soda in the hot water and mix it well. Make sure the baking soda completely dissolves in the water. 

Pour in the drain:

Pour the baking soda and water mix down the sink drain. Wait for the mix to do its work. This should clear up the sink drains soon enough. 

There is another way to get the sink drain cleared up properly and better. It involves the same ingredients just the process is a bit different-

Boil water:

Boil two cups of water and keep it near the sink while it is still very hot. 

Baking soda:

Now you will carefully need to pour half a cup of baking soda down the sink drain. 

Pour the hot water:

Right after the baking soda, pour down the hot water. Make sure The water does not spill.


Wait about ten minutes for the mix to work and do the cleaning.


Bleach is a good way to keep the sink drain clean. Any type of bleach will instantly clean the sink drain. The bleach also prevents any black gunk from forming. The sink is clean and with a lot of debris. 

So there is very little chance of any bacteria building up on the elements. 

The smell of bleach might bother a lot of people as it is very strong. And inhaling the smell of bleach could cause health issues as well. Which is why you can use bleach occasionally and not very often. 

Black gunk on the sink drain can be a bother. It looks bad and is not very hygienic. You will need to clean the sink often to stop the black gunk from forming and coming back.

Even when you have your sink and sink drain is completely clean, the chances of black gunk forming still remain. Which is why you need to clear up the gunk after it forms. The process and methods are not too difficult. Just make sure to give the time and do things properly.

Is black gunk in the sink drain dangerous?

In terms of danger, the black gunk in the sink and sink drains may seem harmless initially. It causes no obstructions at the very beginning. There is no smell or discomfort from it. So it is presumed to be harmless. 

But these black gunk could cause severe damage if they are left unclean. 

There is also a risk of serious health hazard with the unattended black gunk of the sink drains. The obstacles could cause much damage to the interior of the sink. The smell will grow with time. And the gunk is basically bacteria, which should not be left anywhere.

How to prevent black gunk in the sink drain?

Black gunk forming in the sink and sink drains can be a huge bother. It is a problem that most homeowners face and it is especially a problem that is persistent. You will see this problem come back from time to time. But you should try to prevent the issue with some easy steps –

Keep the sink clean. Make sure there is no hair or skin left on the sink. The same goes with soap and lotion grit. Anything left on the sink will cause trouble as bacteria will form on them. The bacteria building up will cause the black gunk to form. 

Make sure you use either baking soda or bleach or vinegar every once in a while to properly clean the sink drains. All these components help clear up the sink drain. Baking soda or vinegar is used more because of the convenience. Bleach is avoided because of the smell. 

Once the black gunk forms make sure to clear it up as soon as possible. An immediate removal of the black gunk will stop the spread of the black gunk. Try to keep the sink drains away from any obstacles. If you find any weird smell coming from the sinks, clean it and don’t take the risk. 

Black gunk should be cleared up as soon as they start to form. There is very little chance to prevent them from forming entirely. Make sure you keep the sink and sink drain clean at all times to stop the black gunk.

Final thoughts

Black gunk in the sink drain are basically the bacteria that has been building up on leftover hair or skin cells. The soap scum and toothpaste grit are also a reason for the bacteria to build up. Make sure to keep the sink drains clean and make sure there is no dirt or debris left to form gunk.