Empty and rinse the tank weekly to prevent mold and bacteria

A dehumidifier tank collects water pulled from the air in your home. That standing water becomes a breeding ground for mold, algae, and bacteria within days if you don't clean it. The good news: cleaning takes about five minutes and requires only water and a soft brush or cloth. You should empty and rinse the tank at least once a week, or more often if you live in a very humid climate or run the dehumidifier constantly.

A dirty tank doesn't just smell bad—it can spread mold spores back into your home when the dehumidifier cycles air. Some units have a drain hose option that lets water flow directly to a floor drain or outside, which eliminates the tank-cleaning step entirely. But if your dehumidifier has a removable tank, cleaning it regularly is the simplest way to keep the unit working properly and your indoor air cleaner.

Key Takeaways

  • Empty the tank completely each time it fills, or at least once weekly, to stop mold and bacteria from growing in standing water.
  • Rinse the tank with plain tap water and wipe the interior with a soft cloth or soft-bristled brush to remove visible buildup.
  • For stubborn algae or mold stains, soak the tank in a solution of one part white vinegar to three parts water for 30 minutes, then scrub gently.
  • Let the tank air-dry completely before reinserting it into the dehumidifier to prevent moisture from pooling inside.
  • If your dehumidifier has a continuous drain option, use it instead of the tank to avoid cleaning altogether.

Step 1: Turn off the dehumidifier and unplug it

Before you touch any part of the unit, switch off the dehumidifier and pull the plug from the wall outlet. This is a safety step—you're working with water and electricity, and unplugging removes the risk of shock. Wait a few seconds for the fan to stop spinning completely.

Some dehumidifiers have a power button that turns off the compressor but leaves the fan running. Unplugging the unit entirely ensures everything stops. Never attempt to remove the tank while the dehumidifier is running or plugged in.

Step 2: Locate and remove the tank

Most dehumidifiers have the tank mounted on the front, back, or side of the unit. Check your manual if you're unsure, but usually you'll see a plastic reservoir with a handle or grip. Gently pull the tank straight out—it may slide or twist slightly depending on the model. Some tanks have a small catch or latch you need to press or flip before the tank releases.

The tank will be heavy if it's full of water. Carry it carefully over a sink, bathtub, or floor drain. If you're emptying it over a sink, tilt it slowly to avoid splashing. Pour all the water out completely.

Step 3: Rinse with plain water and wipe the interior

Once the tank is empty, hold it under running tap water and rinse the inside thoroughly. Use your hand or a soft cloth to wipe down all interior surfaces—the bottom, sides, and the area around the opening. Pay special attention to corners and seams where algae and mold like to hide.

If you see a slimy coating or dark spots, use a soft-bristled brush (an old toothbrush works well) to gently scrub those areas. Don't use a hard brush or abrasive sponge, which can scratch the plastic and create rough spots where bacteria will cling more easily. Rinse again with clean water until the tank looks clear and feels smooth to the touch.

Step 4: Treat stubborn stains with vinegar

If rinsing alone doesn't remove dark stains or a slimy film, fill the tank halfway with a solution of one part white vinegar to three parts tap water. Let it soak for 30 minutes. The vinegar kills mold and algae without harsh chemicals and is safe to use around your home.

After soaking, use your soft brush to scrub the stained areas gently. Rinse the tank thoroughly with clean water at least twice to remove all vinegar smell. If stains remain after one treatment, you can repeat the soak, but usually one round is enough for light to moderate buildup.

Step 5: Dry the tank completely before reinstalling

Before you put the tank back in the dehumidifier, make sure it's completely dry. Water left inside the tank can pool and grow mold again within hours. Stand the tank upright on a clean towel or cloth and let it air-dry for at least 30 minutes, or longer if you have time. You can also wipe the interior with a clean, dry cloth to speed up the process.

Once the tank is dry, slide or twist it back into the dehumidifier until you hear or feel it click into place. Plug the unit back in and turn it on. The dehumidifier is now ready to collect water again with a clean tank.

When to use a continuous drain instead of manual emptying

If you find yourself emptying the tank more than once a day, or if you forget to empty it and come home to an overflowing unit, consider setting up a continuous drain. Many dehumidifiers have a drain port on the back or bottom where you can attach a standard garden hose or vinyl tubing. The hose directs water to a floor drain, sump pump, laundry sink, or outside through a window or door.

A continuous drain eliminates the need to clean the tank at all, since water flows out as soon as it's collected. You'll still want to rinse the tank once a month to prevent mold from growing in the empty reservoir, but you won't have to empty it daily. Check your dehumidifier's manual for the drain port location and the hose size it accepts.

Frequently Asked Questions

Can I use bleach to clean the dehumidifier tank?

Bleach is too harsh for dehumidifier tanks and can damage the plastic or leave toxic residue. White vinegar is safer and just as effective at killing mold and algae. If you want a stronger disinfectant, a solution of one part hydrogen peroxide to three parts water works well and rinses away cleanly.

What if the tank smells bad even after I clean it?

A persistent smell usually means mold or bacteria is growing in the tank between cleanings. Try cleaning more frequently—every three or four days instead of weekly. You can also soak the tank in vinegar solution for an hour instead of 30 minutes. If the smell returns quickly, the tank may be damaged or porous; replacing it is often cheaper than fighting the odor.

How do I know if my dehumidifier tank is full?

Most dehumidifiers have a float switch or sensor that stops the unit when the tank reaches capacity. You'll see a light turn on, hear a beep, or the compressor will shut off. Some units display a "tank full" message. Check your manual for the specific indicator on your model. Never let the tank overflow, as water can damage the dehumidifier's internal parts.

Can I leave the tank in the dehumidifier while it's unplugged?

Yes, you can leave the tank installed while the unit is unplugged. However, if you're not using the dehumidifier for more than a few days, it's better to remove the tank and store it empty and dry. This prevents mold from growing in stagnant water inside the tank during storage.