Why Does My Dehumidifier have Brown Stuff in it (Plus Possible Solutions)

The main function of your dehumidifier is to reduce the humidity levels in your home by collecting excess moisture from the air. Aside from collecting moisture from the air, most dehumidifiers also absorb dust particles, mold spores, and other microbes in the air.

This is often why manufacturers advise you to avoid drinking or using the water collected in your dehumidifier.

So if you are asking yourself, “why does my dehumidifier have brown stuff in it, you should know that the brown stuff mainly comprises mold, dust particles, and other microbes found in the air.

If you clean your dehumidifier regularly, you should note that other factors such as the quality of the water you are using in your home could also discolor your dehumidifier.

This article will offer you insights into the different factors that contribute to discoloration or accumulation of brown stuff in your dehumidifier. The article will also offer you guidelines on the approaches you could use to address these problems.

Why Does my Dehumidifier Have Brown Stuff in It?

Mold, Dust, and Other Microbes

If you notice brown stuff in the water tank or the filters of your dehumidifier, there is a high likelihood that the brown stuff is a combination of mold, bacteria, other microbes, and dirt.

Ideally, the water that passes through the dehumidifier coil is condensed and stored in the water tank. Some of the mold spores, tiny dust particles, bacteria, and other microbes can pass through the coils and settle in the water tank or get trapped by the filter.

If you let the water in your dehumidifier’s water tank sit there for days without emptying the water tank, the water can create a suitable environment for microbial growth and increase the risks of handing mold and other microbes in the water tank.

If you live the water in the dehumidifier for a few weeks or a month without emptying it, you might notice an unpleasant smell when you pry open the water tank.

Possible Solutions for Getting Rid of the Brown Stuff in Dehumidifiers?

Cleaning the Water Tank

  • Cleaning Supplies
  • Water
  • Soap, Chlorine bleach or White Vinegar
  • Cleaning glove
  • A brush or piece of cloth

Cleaning Process 1: Soap and Water

Cleaning is a great way of getting rid of the brown stuff in your dehumidifier. When cleaning your dehumidifier, you should ensure that you have the supplies that you will need and that you have removed the water tank (aka catch basin) from the dehumidifier to ease the cleaning process.

You can opt to use soap and water, bleach, or white vinegar. If you have not cleaned your dehumidifier for a long time and the brown stuff in the dehumidifier has accumulated over time, using soap and water only might not be effective in removing all that sticky gunky brown stuff from the dehumidifier. In such cases, relying on bleach could be a better option.

When cleaning the water tank with soap and water, ensure that you empty the dehumidifier first and then proceed to clean the dehumidifier’s water tank with either a brush or a piece of cloth. Rinse the water tank to check whether you have cleaned all corners well before reattaching the water tank to the dehumidifier.

Cleaning Process 2: Bleach and Water

If you plan to use bleach or white vinegar, you should also empty the water tank first before proceeding.

When cleaning the water tank with bleach, mix a solution of half a cup of chlorine-based bleach with a gallon of water and fill the water tank with the bleach-water solution.

You should remove the water tank from the dehumidifier first and ensure that you have switched the dehumidifier off or switched to continuous drainage.

Ensure that the areas that had become discolored due to mold have been covered by the water. If you notice that the water was not enough, mix another half cup of bleach with one gallon of water and add it to the water tank.

Cover the water tank with a lid and allow the bleach-water solution to sit in the water tank for fifteen to twenty minutes. Empty the water tank and clean the water tank with a soft piece of cloth or soft brush and soapy water. Rinse the water tank well before placing it into the dehumidifier.

Cleaning Process 3: White Vinegar and Water

If you plan to clean your dehumidifier with white vinegar, you should first empty the water tank. If a small section of the dehumidifier has been affected by the mold, you can pour undiluted white vinegar on the area and leave it to stand for about ten minutes. Alternatively, you can fill a spray bottle with white vinegar and spray the affected areas.

Ensure that you rinse the water tank properly after cleaning it with white vinegar. You should also avoid mixing the white vinegar with other household cleaning agents as they have different chemical components.

If you have asthma, allergies or any other respiratory health issues, you should wear a respiratory mask or the regular surgical face mask when cleaning the water tank. This will reduce your likelihood of inhaling the mold spores and microbes in your dehumidifier.

Empty the Dehumidifier When You Are Not Using It

Another approach that would ensure that brown stuff does not accumulate in your dehumidifier is emptying the dehumidifier’s water tank when you are not using it. Leaving the water in the water tank to sit for days creates a suitable breeding site for mold and other microbes.

If you are travelling or you are just in your home but do not plan to use the dehumidifier for a few days, ensure that you empty the water tank and clean it properly.

Simply emptying the water tank might not be enough because droplets of water left in the dehumidifier can still create a breeding site for mold spores and other microbes.

Ensuring that you empty your dehumidifier at the end of the day or after every two days will reduce your likelihood of forgetting to empty the dehumidifier when you plan to leave your home for a few days.

You should also note that leaving the water in the water tank for days without emptying it can contribute to the release of mold spores from the dehumidifier to your home.

Cleaning the Filter

Most dehumidifiers have washable filters, which makes it easy to maintain the dehumidifier. If you have a dehumidifier or recently bought a dehumidifier, you should check the user manual to determine whether the filter in your dehumidifier is washable or if you will need to replace the filter after using it for some months.

If your dehumidifier has a washable filter, simply remove the filter from the dehumidifier, wash it with soap and water, and then rinse it with clean water.

When washing the filter ensure that you use clean water. You can vacuum the filter first before washing it to remove any dirt particles stuck in between the spaces in the filter. After vacuuming the filter, you can soak it in warm soapy water for approximately 10 to 15 minutes before rinsing it.

Avoid using harsh soaps or bleaches when cleaning the filters because the harsh soaps and bleach could damage the filter over time.
You should ensure that you leave the filter to dry before placing it back in the dehumidifier for effective performance.

Changing the Filter

If you notice brown stuff on your dehumidifier’s filter, you can resolve the problem simply by changing the filter. Instead of thinking about buying a new dehumidifier or throwing out the one you have, consider changing the filter (which by the way is much cheaper than getting a new dehumidifier).

If your dehumidifier does not use washable filters, check the instruction manual for guidelines on how long you should use your current filter before changing it. If you are supposed to change the filter, check whether your current filter is worn out and then replace it.

If you notice that your dehumidifier is not removing moisture from the air effectively and you have been using it for a few months, in some cases, the problem could be a clogged overused filter. Ensure that you check your filter after every three to four weeks to assess its condition.

Some of the dehumidifiers that have replaceable filters might need filter replacement once or twice a year. Ensure that you understand the specifications for the brand of dehumidifier that you are using and the maintenance requirements before attempting to change the filter.

Vacuum the Dehumidifier

If you notice that a lot of dust has settled on your dehumidifier, you should use a hand-held vacuum to vacuum the dehumidifier. This will ensure that any dirt or dust that might have settled on the tiny crevices of your dehumidifier have been removed.

How to Prevent Brown Stuff from Accumulating in My dehumidifier

Opting for Continuous Drainage

If you keep noticing brown slime in your dehumidifier after every few days, you could opt for continuous drainage. Continuous drainage entails using a hosepipe that is either bough along with the dehumidifier or separately and connecting it to the dehumidifier then directing it to a drain outlet.

Today, most of the dehumidifiers available in the market come with a drainage pipe that you could use to drain the condensed water drawn from the air in your home by your dehumidifier.

If you plan to use the continuous drain option, you should ensure that you place the dehumidifier close to a drain or sink to avoid water spills.

You should also ensure that you clean the hosepipe or drainage pipe at least once after every three to four weeks to remove any dirt or mold that might have accumulated inside the hose pipe. To clean the hosepipe, simply disinfect it with a solution of white vinegar and water.

You can follow these simple steps to clean the drainage pipe/hosepipe for your dehumidifier.

Step 1: In a bucket pour 1 cup of white vinegar and add 1 cup of water.
Step 2: Detach the hosepipe from the dehumidifier.
Step 3: Pour the white vinegar and water solution down the hosepipe to disinfect the pipe and kill any microbes that might have accumulated there.
Step 4: Ensure that the end of the hosepipe is directed towards the drainage.
Step 5: Reattach the hosepipe to the dehumidifier.

If you noticed that the hosepipe has lots of mold-like substances or a nasty smell, you could create a stronger concentration of the disinfectant by increasing the ratio of white vinegar to the water.

Try using three-quarter parts white vinegar and a quarter part water. This would mean that in a three-quarter cup of white vinegar, you will only add a quarter cup of water.

Empty and Dry the Water Tank during Storage

If you do not plan to use your dehumidifier for a few weeks or months, you should ensure that you empty, clean, and dry the dehumidifier before storing it. A clean and dry dehumidifier is less likely to promote mold growth.

Use the Dehumidifier Timer

Some dehumidifiers have timers that remind you when to clean or replace the filter in your dehumidifier. Ensure that you clean your washable filter or replace it when the timer reminds you to do so.

Use a Phone Reminder

If your dehumidifier does not have a reminder to help you remember when you need to clean the dehumidifier or change the filters, you can add a reminder on your phone that will help you remember to clean the dehumidifier.

When you are using a continuous drain dehumidifier in your basement or a room that you rarely use, it is easy to forget about cleaning your dehumidifier. Setting a reminder will help you remember when you need to clean the drainage hosepipe or change the filter.

Avoid Placing the Dehumidifier Near Dusty Surfaces

Avoid placing the dehumidifier near dusty places. It is nearly impossible to avoid dust, especially during summer. Some factors can significantly increase the levels of dust particles in the air.

For instance, if you keep your farm tools in your basement, they are likely to bring in the dust unless you always clean them before storage. Similarly, if you like DIY projects like molding clay or carving wood, the room that you use for these projects can have high dust levels.

Keeping a dehumidifier in a room with high levels of dust or dirt increases the risks of filter blockage and accumulation of some of the dust and dirt particles at the bottom of the water tank of your dehumidifier.

If you plan to use your dehumidifier in such rooms, try keeping the dehumidifier in the farthest corner of the room, away from your DIY projects.

You could also consider cleaning the filter or changing it regularly to ensure that the dehumidifier works properly and to avoid blockage of the filter.

Related: Best Dehumidifiers for 1000 sq. ft. Basement


Dehumidifiers are quite easy to use and maintain. If your dehumidifier has brown stuff in it, there is a high likelihood that the brown stuff is a combination of mold spores, bacteria, and other microbes found in the air.

Ensuring that you clean your dehumidifier properly and that you empty the water tank regularly will reduce the likelihood of mold growth in your dehumidifier.


What is the brown stuff in my dehumidifier?

The brown stuff that accumulates in dehumidifiers usually comprises mold spores, dust particles, and other microbes drawn from the air around your home.

How do I clean the gunk out of my dehumidifier?

You can use soap and water to clean the gunk out of your dehumidifier. Ensure that you use a mild soap. If the stains do not come out easily, consider using bleach to remove the dirt.

When cleaning the reservoir or water tank with soap and water, fill the water tank with water then add the soap. You can allow it to sit for a short while to loosen the dirt before scrubbing it off with a soft brush. Ensure that you rinse and dry the water tank properly afterwards.

Can I use bleach to clean my dehumidifier?

Yes. While you can use bleach to clean the water tank in your dehumidifier, you should avoid using bleach on any other part of the dehumidifier.

Bleach has antibacterial properties and can be useful in killing any microorganisms like mold spores and dust mites. Bleach will also get rid of any moldy or unpleasant smells in the water tank.

Can I use white vinegar to kill mold?

Yes. White vinegar is slightly acidic and can be used to kill mold and other microbes. If your dehumidifier has mold, you can use white vinegar to get rid of the mold by spraying undiluted white vinegar directly on the mold spores and leaving it to sit for a while before cleaning the water tank.

Why is my dehumidifier dirty?

The dirt inside your dehumidifier is mainly composed of mold. Cleaning your dehumidifier regularly can reduce the risks of mold growth.

Just like other devices in your home, dust and dirt can settle on your dehumidifier over time. When cleaning your dehumidifier, ensure that you wipe the external area or use a hand-held vacuum cleaner to get rid of the dust.

How many years does a dehumidifier last?

Ideally, a good dehumidifier can last between five to ten years. You should note that the longevity of your dehumidifier relies on how you use it, whether you clean the dehumidifier and the washable filters as recommended, and your adherence to other manufacturers’ guidelines that might be associated with the specific brand of dehumidifier that you are using.

You should also note that not cleaning your dehumidifier as required can contribute to the accumulation of mold spores and dust particles inside the dehumidifier. This could reduce the efficiency of the dehumidifier over time and limit its ability to draw moisture from the air.

If your dehumidifier uses washable filters, ensure that you clean the filters regularly. On the other hand, if your dehumidifier uses replaceable filters, ensure that you follow the manufacturer’s recommended timeline for replacing the filters.

Will a dehumidifier help with musty smells?

Yes. Dehumidifiers can help reduce musty smells in your home. The musty smell in a home is often associated with humidity and the microbes that thrive in humid areas.

Reducing the humidity to the recommended levels will also get rid of the musty smells and leave your home smelling nice and fresh.

If the musty smell is coming from the water tank of your dehumidifier, then you will need to clean the water tank with soap and water. You could also use a disinfectant after the initial cleaning to ensure that any microbes that might have accumulated in the water tank have been destroyed.

Note that, musty smells from the water tank occur when you leave the water in the water tank sitting there for days instead of emptying it.

Meet the Author

The author is a blogger, interior design and home improvement enthusiast, and researcher, with a passion for helping people improve their homes by creating a calming and beautiful environment. Check out the about author page to learn more about her work