How to Get Rid of Black Gunk in Sink Drain

Mold, mildew, and other particles rinsed inside the sink create a black sludge in the sink drain. The clogging mostly happens because of the build-up of the black sludge. To ensure a sink drain discharges black debris you will need to use proper cleaning methods, otherwise, there is a risk of damaging the pipes.

The sludge can also be called mold. Most mold is not toxic, but the greenish-black one is toxic. If the black sludge starts coming up the sink, it is time to clean it up. If the sludge is not removed, it can become a health hazard.

How to Get Rid of Black Sludge in Sink Drain

How to Get Rid of Black Mold in Sink Drain

There are three easy and efficient methods to get rid of black sludge in the sink drain. All three methods are effective in making bathroom sink drains slime-free. They require items that are easily available and simple to use. With these methods, you can make the sink drain free of gunk without any professional help.

Using Baking Soda, Water, and Vinegar Mixture

Removing black sludge is very important for maintaining a clean and hygienic bathroom space. The details of the first method are as follows:

Things You Need:

  • One cup of white vinegar
  • One cup of baking soda
  • Half gallon boiling hot water

Step 1: Boil Water

The first step is to boil water. Take a pot that contains half a gallon of water and put it on a stove. Turn on the stove and continue boiling until steam starts appearing and water bubbles are shown.

Step 2: Put Baking Soda into the Sink

Take half a cup of baking soda and dump it into the sink. You should not worry if tough clogs are formed as they will be dissolved later. Boil the water in the meantime

Step 3: Pour Vinegar into the Sink

Take a measured portion of vinegar. Pour this liquid over the baking soda. The two ingredients act together and react to create bubbles and fizzles.

The mixture will loosen up the accumulated black sludge in the sink. This results in unclogging of the sink. Leave the mixture there and wait for the water to boil.

Step 4: Run Boiling Water Over the Mixture

Pick up the boiled water pot and pour it carefully into the sink. Avoid splashing the liquid out of the sink. Keep rinsing the water over the vinegar and baking soda mixture until it unclogs the holes.

Wait for some time to check the effectiveness of this method before moving on to the next step. If there is still blockage, repeat the above process again.

Using a Drain Cleaner

Things You Need:

  • An over-the-counter drain cleaner
  • Plastic Gloves
  • Hot water

Step 1: Pour the Cleaner into the Sink

The drain cleaners are chemicals composed for opening clogged holes in the kitchen, washroom, etc. They dissolve the clogged particles and clean the holes for free passage of water. Some cleaners can be harsh on your skin so you must wear gloves before getting in contact with it. Pour the cleaners into the sink carefully. Aim it into the sink rather than dropping it here and there. Make sure that you have poured enough cleaner to dissolve the clogged particles.

Step 2: Wipe the Sink Clean

You must wipe put every drop of cleaner from the surface of the sink as it can stain it if left for a long time.

Step 3: Wait for the Results 

Read the instructions on the cleaner thoroughly. The time each cleaner takes to completely dissolve the sludge differs. Wait for that particular time and avoid filling the sink with water during this time.

Step 4: Pour Hot Water Into the Skin

Flush the sink with boiling hot water. This will result in removing the cleaner and dirt from the sink.

Clean Sludge Manually from Pipes 

The blank gunk that gathers into the bathroom sink can be removed manually. This method doesn’t involve using any cleaners or ingredients. It can be complex but if the instructions are thoroughly followed, the results are amazing. Stop any water flow to the sink while cleaning. Take a heavy object e.g. a wrench or hammer, etc., and break the clogs in the pipes manually. Clean the pipes by washing them and removing any sludge present inside them. The sink will be unclogged after the cleaning process.

These 5 Things Cause Black Gunk in Bathroom Sink Drain

The water in your sink may be sinking slowly because of a buildup of junk in the drain. It shouldn’t come as a surprise that it may happen in your kitchen sink or bathroom sink, as it occurs to almost everyone. Because of the high volume of usage, the sink quickly becomes clogged due to improper waste disposal and accumulation. Black slime, or black sludge, is the result of this process.

1. Clog

A clog could be causing the black substance to pour out of your sink drain. Biological stuff makes up most blockages. As a result, germs flourish in the clog, turning it black. Use an auger or plunger to clear the blockages and prevent the black debris from backing up into the sink drainage.

2. Growth of Bacteria

Grease, filth, oil, hair, and other particles stay together and increase over time, whether you’re washing your hands or rinsing your toothbrush. All of these substances are together in the slime you see. This bacterium grows and spreads over time, especially because the substance that travels down these drains is organic in nature, giving food for the bacteria to eat.

The trouble with this black sludge is that it won’t go away quickly, and putting more water down the drain or waiting for it to unclog on its own won’t help.

3. Breakage in the sewage line

A break in your sewage line, potentially caused by roots, may be caused by dirt pouring up any drain, particularly the floor drain. When you use a sink, most of the waste will go down the drain line, but some will get stuck on the internal surface of the pipes. Aside from appearing and smelling bad, the black biofilm in your sink drain can cause a foul odor and perhaps cause health problems.

4. Sink drain design

Sometimes black sludge in sink drains is due to the sink drain’s design, which permits more waste to accumulate inside the drain line in the sink.  For example, some bathroom sink drains include a popup stopper with a mechanism that is normally located inside the drain line.

5. The sink is rarely used

If a sink hasn’t been used in a while, there’s a potential for black sludge to grow inside the drain. So, before going on a long trip, give your sink drains a thorough cleaning and degreasing. Grease and food debris are removed, preventing sludge growth.

Is Black Mold in Sink Drain Dangerous?

A lot of things pass through the sink drain every day which leads to the build-up of black slime.

Regularly cleaning the sink drain is important because clogged drains do not last for a long time. When you remove black stuff coming up from the sink drain you are increasing its lifespan.

When the particles of food, hair, shampoo and other debris get stuck in the drain, it leads to mold growth.

When they stay stuck in the drain, the bacterial growth starts emitting a foul odor. With clogged drains, you constantly have to deal with nauseating smells.

The build-up of sludge in the sink drain affects its drainage speed. A clogged sink drain can become a problem.

Regularly cleaning ensures the sink drains quickly and the water and other particles do not float in the sink.

Failing to schedule regular cleaning of sink drains can be costly. The small issues keep building and you end up with overflowing and damaged pipes.

How to Stop Black Slime Growth in the Bathroom

The areas that are exposed to water are vulnerable to the growth of black slime. The areas in the bathroom that are frequently exposed to moisture like sinks, faucets, etc. are perfect for bacterial growth. 

You can use the following tips to remove black sludge from the bathroom sink drain.

  • The humidity level in the bathroom can get pretty high which results in mold growth. To prevent slime growth, keep the humidity levels between 40 %- 60%. If you are constantly facing a mold problem you should invest in a dehumidifier. 
  • If you notice any leaks in the sink pipes, make sure you fix them without any delay. 
  • Make sure that the drain has a drain gate or screen. It will prevent hair and other debris from going down the drain and turning into black sludge. 
  • Clean the drain screen or gate and remove debris such as hair regularly to eliminate black gunk in the sink drain. 
  • Use a non-abrasive cleaning solution containing bleach to clean moldy areas and prevent them from becoming stubborn sludge.


A lot of things go through the sink drain on daily basis. In the bathroom sink hair, dirt and soap constantly make their way to the sink drain. All these things keep accumulating in the drain and turn into toxic and bad-smelling black sludge.

If the sink drains are not cleaned regularly, the black slime continues to grow and it can destroy the pipelines. To get rid of black sludge from the sink drain, it is essential to schedule drain cleaning. Timely action will save a lot of money in expensive repairs. Inspect the moldy area thoroughly and remove it with extreme care.

Lisa Burks

Hi, I'm Lisa Burks, founder of the Sink Formula blog, and plumber of 5 years experience.

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