5 simple ways to tell if your dehumidifier is *actually* doing its job according to experts – and what to do if it's not

If you've got a dehumidifier humming away in the background, but you're still battling condensation or your washing isn't drying as fast as usual, it's only natural to wonder whether it's actually doing anything at all.

I've tested some of the best dehumidifiers in my own home, and I've learned that when one is working properly, the signs are easy to spot when you know what to look for.

In my own experience, it usually boils down to simple dehumidifier mistakes like using it in a room that's too cold or blocking the airflow. So before you give up on your dehumidifier or replace it with another one, I've asked the experts for five simple checks you can do right now to see whether your dehumidifier is actually doing the job it's supposed to.

Here are the signs the experts say you should look out for.

1. Check the water level in the tank

It might sound pretty obvious, but it's the quickest and most reassuring sign your dehumidifier is working. If it's collecting water from the air, the water will fill up in the tank, says Katie Lilywhite, AO.com's small appliances expert.

'If the water level is filling up and regularly needs emptying, that is a sign that your dehumidifier is effectively picking up moisture and therefore in good working order,' explains Katie.

A small amount of water after a few hours is completely normal, especially if you're running it in a relatively dry room. In damp spaces like bedrooms with window condensation issues or a utility room, drying laundry indoors in winter, you should see the tank filling up more over a day or two.

If there's no sign of water at all, it's worth doing these checks:

• The tank is properly fitted in the unit
• You're not already at or below your target humidity level set on the unit

2. Feel for the airflow

Katie says, it may seem obvious, but feeling for the airflow is one thing people seem to forget to check, as a dehumidifier should be actively pulling in and pushing drier air back out again.

'Simply place your hand above the extractor fan, maintaining a safe distance, and feel for airflow – if there is no or little airflow, it indicates that your dehumidifier is not functioning,' advises Katie.

You should feel a steady stream of air, even if it's fairly gentle but not weak. If there's little or no airflow, that's a sign it's not working properly.

If there's not much airflow, it's worth checking the following:

• The air filter isn't clogged with dust or fluff
• The unit isn't pushed up against a wall
• Nothing is blocking the air vents

Katie Lilywhite

AO's latest addition is Katie, a key expert at a multitude of appliances, including dehumidifiers, portable air conditioners, fans and air purifiers. 

3. Measure the humidity of the room

Dehumidifiers usually have a digital display, and this is one of the handiest tools you've got. When the machine is working, the percentage should gradually fall over time.

Katie explains that you can measure the overall humidity of the room using a hygrometer to see if the dehumidifier is effectively reducing the humidity to a comfortable level. 'A measure of between 30-50% humidity is an indicator that your dehumidifier is working,' advises Katie.

A good idea would be to take a quick note of the humidity level when you switch it on, then check it later the same day. A slow drop is normal, but the same number isn't.

Chris Michael, CEO of Meaco, adds that 'if the unit becomes quieter or switches on and off, this is usually a sign it is set to target humidity mode and is regulating itself as designed.'

Chris Michael

Chris founded leading dehumidifier manufacturer Meaco and has been advising on humidity solutions and dehumidifiers since 1991 and is well-known within the dehumidifier industry across the world as a leader in innovation and sustainability. With a wealth of experience in the industry, Chris is committed to helping provide low-energy and low-noise solutions appliances that improve the lives of customers.

4. Check the temperature of your home

The temperature of your home has a big impact on how well your dehumidifier can work, and sometimes it's recommended not use a dehumidifier in winter at all if your home is too chilly, advises Chris Michael.

'Colder spaces slow moisture extraction and make the process less noticeable,' he explains.

Most compressor dehumidifiers perform best in rooms that are at least around 15°C, so if your home is much colder than that, say in spare rooms, utility spaces or during cold snaps, your dehumidifier will slow down its efforts.

If you're using a dehumidifier in a consistently cold house, a desiccant dehumidifier like Meaco's DD8L Pro Desiccant dehumidifier, £259 at Amazon, is a better option in these conditions.

5. If it's helping the problem you bought it for

The most obvious and most important check of all is whether the dehumidifier is actually solving the problem you have in your home.

'Practical changes such as reduced condensation on windows, quicker indoor laundry drying and no more damp smells are often the clearest indicators that a dehumidifier is working properly,' explains Chris.

If you can spot improvements to your humidity woes over a number of days, your dehumidifier is working the way it should.

Dehumidifier troubleshooting

If your dehumidifier still doesn't seem to be working, and before you decide it's faulty, you should check the following:

• Filters are clean, and the airflow isn't blocked
• The doors and windows are mostly closed in the house
• You have the correct size of dehumidifier for the size of your house
• The target humidity isn't set too low

The best dehumidifiers we've tested

A working dehumidifier collects water, lowers humidity and makes your home feel more comfortable over time. If you can tick off even two out of these checks, it is doing its job!

However, if it's not, you might need to look at choosing a new dehumidifier that's right for your home.