How to Store a Dehumidifier in the Off-Season

Why storage preparation matters

A dehumidifier is a moisture-control appliance: it pulls water out of the air and holds it in a bucket or sends it down a drain. The EPA's key to mold control is moisture control, and the same logic applies to the machine itself. If you put a damp unit into a closet, basement or garage for months, the leftover water in the bucket, hose or drip tray can become a place where mold starts. The CDC says mold will grow where there is moisture, and keeping humidity low with a dehumidifier is one of the ways to prevent that growth. Storing a clean, dry unit protects both the appliance and the room you bring it back to.

The EPA also advises drying water-damaged areas and items within 24 to 48 hours to prevent mold growth. A dehumidifier that sits wet for a whole off-season gives mold plenty of time to establish itself. Mold gradually destroys the things it grows on, so a damp storage period can damage seals, filters or interior plastic. Start with a clean, dry machine and you avoid that problem.

If your current unit is old or no longer dries properly, storage prep is also the time to decide whether to replace it before the next humid season. See best dehumidifiers for basements or under-50-pint dehumidifiers when you shop for a replacement.

Clean the unit before you store it

Unplug the dehumidifier first. The Department of Energy defines a dehumidifier as an electrically operated, mechanically encased assembly with a refrigerated surface, a refrigerating system, an air-circulating fan, and a means for collecting condensate. That means water, electricity and moving parts are all in one housing, so keep the cord unplugged while you work.

Remove the bucket and empty every drop. Rinse the bucket with plain water, then wash it with a household cleaner if it has touched standing water. The CDC says mold can be removed from hard surfaces with household products, soap and water, or a bleach solution of no more than 1 cup of household laundry bleach in 1 gallon of water. Never mix bleach with ammonia or other cleaners, follow the label directions, and work in a ventilated area.

Wipe down the exposed coils, the drip tray and any plastic panels you can reach. For visible mold on hard surfaces, use the same soap-and-water or bleach approach. The University of Minnesota Extension adds that surfaces that have been cleaned should be rinsed and dried thoroughly, and that porous items that cannot be cleaned should be thrown away. If a filter is disposable, replace it before storage; if it is washable, clean it as part of storage prep. For more detail, see dehumidifier filter maintenance.

Dry the inside, bucket and drain components

The easiest way to dry a portable unit is to remove the bucket, drain any condensate from the internal tray, and leave the bucket outside the machine while the unit air-dries in a dry room. This follows the EPA's central advice: moisture control is the key to mold control. A dry bucket is hard for mold to grow in; a wet one is not.

If the unit has a built-in condensate pump, check the pump reservoir and the drain hose. Pump models collect water in a small internal tank before moving it to a hose, so hidden water can remain after the main bucket is emptied. Store the hose coiled loosely, and make sure no water stays trapped in the hose. See built-in pump vs gravity drain and continuous drain hose setup for how these systems differ.

Wipe any remaining moisture from the air inlet and outlet grilles. You do not need to disassemble the sealed refrigeration system; leave the refrigerant loop alone. A can of compressed air or a soft brush can dislodge dust from the grilles and fins, but do not bend the fins. If the owner's manual gives specific storage instructions, follow those.

Clean or replace the filter and check accessories

A filter that spent the summer catching dust and mold spores should not sit in the machine for months. Clean a washable filter according to the manufacturer's instructions, or replace one that is dirty or damaged. A clean filter also makes the first startup of next season easier, because airflow is not blocked.

Check the power cord for cracks or exposed wire. Also check the bucket, handle and wheels. A small crack in the bucket can turn into a leak next summer. If any part is worn, order a replacement before the humid season starts, or factor it into your buying decision. If you are comparing current models, the best pump included dehumidifiers guide can help.

Pack the dehumidifier for storage

Store the unit upright, the same way it operates. Portable dehumidifiers are mechanical assemblies with a compressor and refrigerant loop; laying them on their side can move internal oil or refrigerant where it should not go. If the manufacturer says a model can be laid flat, follow that instead.

Put the dry bucket back in place or keep it beside the unit so you do not lose it. Coil the power cord loosely, and avoid wrapping it tightly around the machine, which can stress the cord. Keep the hose, owner's manual and any small parts together in the bucket or in a labeled bag.

Keep the unit away from dust if you can. A large plastic bin without a sealed lid, or a clean sheet, is enough for most homes. For storage situations that are more exposed, see dehumidifier in garage or unfinished space.

Choose a storage location

The best place is a dry, climate-controlled room, not a damp basement or an unheated garage. The CDC says to keep humidity levels in your home as low as you can, no higher than 50%, all day long. If your storage space has high humidity, the stored unit can pick up moisture even when it is not running. Elevating it off the floor with a shelf or pallet keeps it away from small leaks and condensation.

ENERGY STAR notes that frost can form on condensing coils if air temperature drops below 65 degrees Fahrenheit, and that can make the compressor cycle without removing moisture. That guidance is for running the unit, but it also shows that a freezing or near-freezing storage spot is not ideal for a device with water and a compressor. If you must store it in a cold garage, dry it completely and bring it back to room temperature before turning it on.

Before you start it next season

When the weather turns humid again, inspect the unit before plugging it in. Pull out the bucket, check the filter, look at the hose and confirm the coil area does not smell musty. If you see or smell mold, clean it before running the unit. The CDC is direct: if you see or smell mold, remove it. A dehumidifier should be part of the fix for indoor moisture, not a source of mold.

Let the unit sit at room temperature for a while if it was stored in a cold spot, then set it up following the same placement rules you used last season. If you are not sure whether the machine is still the right size for the room, review pint rating explained and sizing dehumidifier by square feet.

If the unit no longer works reliably after storage, the best moment to replace it is before the humid season, not after the basement gets damp. The guides below will help you choose by capacity, drain setup and energy use.

What to pick for your use

Questions

Can I store a dehumidifier with water in the bucket?

No. Empty the bucket, rinse it, dry it, and check the drip tray or pump reservoir for leftover water. Mold grows where there is moisture, and a sealed bucket of water can turn into a mold problem before the next season.

Should I store it in a basement or garage?

Only if the space is dry and climate-controlled. The CDC recommends keeping indoor humidity no higher than 50% all day long. A damp or unheated space can add moisture to a stored unit, so elevate it off the floor and protect it from dust if you must keep it there.

Do I need to use bleach to clean the unit?

Bleach is not always required. Soap and water or a household cleaner can work for hard surfaces. If you use bleach, the CDC says a solution of no more than 1 cup of household laundry bleach per 1 gallon of water is acceptable, and you should never mix bleach with ammonia or other cleaners.

How do I keep the drain hose from getting moldy?

Drain the hose completely, wipe any moisture from the outside, and coil it loosely for storage. If the inside of the hose smells musty, run a cleaning solution through it or replace it before the next season.

What if the unit smells musty at the start of next season?

Clean it before running it. Wash the bucket and hard surfaces with soap and water or an approved bleach solution, replace or clean the filter, and dry everything fully. If mold has soaked into a porous part that cannot be cleaned, replace that part.

Can I lay a dehumidifier on its side to store it?

Check the manual. For most portable compressor units, keeping the machine upright is the safer choice because the compressor and refrigerant loop are not designed to be turned sideways. If the manufacturer allows it, follow the instructions exactly.