The Hidden Danger in Your Dehumidifier! Biofilm Buildup and Gunk Inside

Your dehumidifier is supposed to protect your home from excess moisture, mould, and musty smells. But what if the very device meant to improve your indoor air quality is actually making it worse?

That slimy gunk inside the tank or coating the coils isn’t just dirt...yuk..it’s biofilm, a stubborn buildup of bacteria, mould, and fungi that thrives in damp conditions. Left unchecked, it can turn your dehumidifier into a hidden health hazard.

What is Biofilm (a.k.a. “the gunk”)?

Biofilm is a sticky, slimy layer where microorganisms live together in a protective shield. Once it takes hold inside your dehumidifier, it’s tough to remove and can keep releasing airborne microbes every time your unit runs.

Think of it as a microscopic swamp inside your dehumidifier, out of sight, but never harmless.

Why Biofilm in Dehumidifiers is Dangerous

Air Quality Concerns. Contaminants can be blown back into the room, lowering indoor air quality.
Health Risks ...YES...Biofilm contains bacteria and mould spores that may trigger allergies, asthma, and respiratory irritation.
Unpleasant Odors...YUK.. A musty, dirty-water smell is often the first red flag.
Reduced Performance ! Gunk buildup on filters and coils makes your dehumidifier work harder, using more energy while doing less.
If your a resotration cotractor now you birng this into someone HOME!

Final Word

Your dehumidifier is a powerful tool for moisture control — but without cleaning, it becomes a breeding ground for biofilm and gunk. A little regular maintenance keeps it working for you, not against you.

Pro Tip: Add “dehumidifier cleaning” to your monthly home maintenance checklist. It’s a small step that protects your air quality, your health, and your equipment

Safety & Setup

Power off & unplug the unit. Let it sit 5–10 minutes.
PPE: gloves, eye protection, and a P2/N95 respirator (biofilm aerosols are gross).
Work over a tray or drop sheet. Keep electronics dry at all times

“In most commercial water-damage restoration dehumidifiers you’ll unscrew the hood of the rotomoulded body and remove the pump. As you can see from the photo, biofilm and gunk can build up here, causing leaks, smells, or a full failure to drain.”

How to Clean Biofilm and Gunk from Your Dehumidifier

When dealing with biofilm, mould, and general gunk buildup in commercial restoration dehumidifiers, here’s a simple process:

Clean the Tray / Reservoir
- Spray RestoAir™ Degreaser into the tray body.
- Scrub away residue and rinse thoroughly with clean water.
- This step removes the heavy sludge that collects at the bottom.
Clean the Coil
- Apply a RestoAir™Coil Cleaner (as shown in the photo) directly onto the evaporator coil.
- Allow 20 minutes of dwell time for the cleaner to break down biofilm and grime.
- Rinse gently with water.
- You’ll notice the coil becomes instantly brighter and cleaner.
Pump Tray Treatment
- Add a RestoAir™ Dehumidifier Pan Tablet to the tray or pump pan.
- These slowly dissolve and continue to fight mould, algae, and biofilm buildup over time.
Final Rinse & Inspection
- Rinse everything again with clean water.
- Check hoses and discharge lines — make sure they are free from mouldy biofilm.
- Once complete, the coil and tray should be clear, leaving you with a cleaner and more efficient dehumidifier.

Pro Service Option
Not everyone has the time to strip down and clean a fleet of dehumidifiers. If you’d like it done for you, BULCS Holdings will clean any dehumidifier for just $30 per unit + GST.

Give us a call today and keep your dehumidifiers running at peak performance!

1300 654 684 or email hello@bulcsholdings.com.au