Guide · Home care

Portable Dehumidifiers

A plain, friendly guide to running a portable dehumidifier well: a good humidity setting, a hose that drains on its own, a clean filter, and why cold rooms are tricky.

Start the checklist

Where to start

It stopped and says the bucket is full?
The drain hose probably has a hump or a loop in it. See set up a hose that drains on its own.
A room still feels damp?
Check the setting and the filter in the checklist, and read if the room stays damp.
Just got one?
Start with the short version, then tick through the checklist.

The short version

A portable dehumidifier pulls damp air across cold coils. Moisture turns into water and drips into a bucket or out through a hose. It is a big help in basements, laundry rooms and damp living spaces.

Most homes do well between 30% and 50% relative humidity. Below 50% makes life hard for mold and dust mites. There is usually no need to set it lower than 30%.

In winter, if water collects along the bottom of window glass, try a lower setting, around 30% to 40%.

Emptying a bucket twice a day gets old, and the unit shuts itself off when the bucket is full. A drain hose lets it keep going on its own.

Who does what

Every home and lease is a little different, so these are examples. When you are not sure, ask first.

Residents can often

Choosing the humidity setting
Washing the filter
Setting up the drain hose
Emptying the bucket and checking the float moves freely

Leave to the owner or a pro

A room that stays damp no matter what, which can point to a leak or a drainage problem
Water on floors or walls, or a musty smell that will not go away
Any question about using a floor drain or sump in a shared space

Set up a hose that drains on its own

Find the drain port on the side or back of the unit and remove its rubber cap or plug.
Thread on a standard garden hose or the tubing the maker suggests. Make sure the rubber washer is seated inside the hose fitting, so it does not leak.
Run the hose to a floor drain, sump basin or laundry sink, and keep it away from electrical cords and outlets.
Keep the hose sloping downhill the whole way. Unless your model has a built in pump, the water only flows downhill, so any hump, loop or kink traps water, and the unit backs up and shuts off.
Check it again after a day or two to make sure water is flowing and the floor is dry.

Keep the filter clean, and mind the cold

Slide out the filter about every two weeks, or as often as the maker says, and more often in dusty rooms. Wash it in warm water with a drop of dish soap, rinse it, and let it dry completely before it goes back in.
Do not run the unit without its filter. Dust can build up on the coils and keep it from working well.
Most portable units work best when the room is above about 65°F. Below that, frost can form on the coils, and the unit may stop to defrost.
For spaces that stay cold, like an unheated garage, a model made for low temperatures does a better job.

Try it

Your dehumidifier checklist

From the guide’s own checklist. Tick each one as you go. These are examples; your home may need others.

0 of 6

Humidity set between 30% and 50%
Filter washed, dried and back in place
Drain hose snug, with its rubber washer inside
Hose slopes downhill the whole way, no dips or loops
Bucket float moves up and down freely
Room stays above about 65°F, or the unit is made for cold spaces

If the room stays damp

Check the setting, the filter and the hose first.
Make sure doors and windows in that room are closed while it runs.
If it still feels damp, smells musty or you see water on floors or walls, take photos.
Message your owner and share what you tried. Steady dampness is worth a closer look.

Sharing it early helps everyone. Moisture problems are always easier to fix while they are small.

An everyday example

A dehumidifier in a damp basement was hooked up to a hose running to a floor drain. Two days later it sat silent with a bucket full warning, and the floor was still damp. The hose looped up and over a box of tiles before dropping to the drain. Laying the hose flat on the floor got the water flowing, and the room dried out over the next few days.

Test yourself

How much do you remember?

4 quick questions from this guide, with a one line why for each. Totally optional, no sign in, and your answers are never saved.

From The Perfect Series

Go deeper with The Perfect Seasonal Home Care Checklist Workbook

Fall, spring and everything in between. Simple, step by step checklists you can write in, one topic at a time, to help any home stay warm, safe and dry all year.

See The Perfect Seasonal Home Care Checklist Workbook All books in The Perfect Series

Keep this guide handy

Save this page, come back to your checklist any time, and share it with anyone in your home who could use it.

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From the Bunklow shop

Take it with you

Bunklow Home Guide 012: Portable Room Dehumidifiers, Continuous Gravity Drains, and Target Humidity ControlA printable guide to portable room dehumidifiers, continuous gravity drains, and target humidity control, in plain steps.
See it in the shop
Healthy Home Checklist PackThe Healthy Home checklists in one pack, fillable on screen or printable.
See it in the shop

Sold on Payhip.

This guide shares general information to help you, and is not legal, tax or safety code advice. Rules vary by state and city, so check with your local officials or a qualified professional. Please follow the maker's instructions for your equipment. Bunklow does not inspect properties or make repairs.