My Humidifier Smells Musty: Is It Dangerous?

Why does my humidifier smell weird, and how can I fix that nasty smell?

Cool or warm mist humidifiers are very good for increasing the humidity level in your indoor living spaces.

However, as we have seen in the past, they do have their share of trouble. For instance, a humidifier can stop working after cleaning. We have also looked at the issue of Pure Enrichment failing to work at all.

And many more, including Crane humidifier not working.

Today, we shall look at the different types of humidifier smells and what they mean.

Why does my humidifier smell musty?

Why does my humidifier smell musty

In addition to smelling musty, also check whether the humidifier has signs of mold, in the form of black, gray, or pink slime in the tank.

Bacteria, mold, grease, and gunk cause a weird, musty smell. It is an indication of just how much you have neglected the unit.

Unfortunately, if you continue running it, it will disperse the mold and bacteria with the mist, and your family will inhale them.

Long exposure to mold can cause mold toxicity signs. If you have a baby in the house, this fungus can also cause serious mold exposure symptoms in young kids.

How to remove the musty smell

You will have to clean the humidifier tank with vinegar to kill the mold. You can also use bleach, but remember to never let it mix with vinegar because it forms a poisonous gas.

Create a consistent cleaning schedule for your unit if you use it regularly.

If the odor is too much, especially for people who have large portable humidifiers, you could use an air purifier to remove the musty smell.

It smells like plastic

Why does my humidifier smell musty

According to an explanation given by, if a humidifier produces a plastic smell when it is new, there is nothing to worry about.

This is called the smell of newness, and it should disappear in a few days. You don’t need to do much about it.

Most electronics do have this smell when they are new. Mostly because they have been enclosed in airtight spaces since the manufacturer made them or since they were dispatched for shipping.

How to remove plastic smell

Just keep the humidifier in a space with enough air circulation, or if you can live with the smell (it’s not too overwhelming), just leave it. It will disappear on its own.

If you use the humidifier for several minutes and then return it to the box it came with, it will still smell like plastic the next time you get it out.

Keep it in the open, in a well-ventilated space, or even outside if you want.

Why does my humidifier smell like fish?

Why does my humidifier smell like fish

The smell of fish from your humidifier is very close to the musty smell that we looked at earlier. It is caused by mold, bacteria, and dirt.

If your humidifier has a filter, this is most likely the culprit. It has trapped bacteria, mold, grease, and minerals from the tap water that you have been using.

Left for days, these things can start producing a nasty fish smell in your unit.

There is also another thing to consider… Many times, the smell of fish in a place that has appliances means some electrical part is burning.

It could be a burning power cord or a blown fuse. Luckily, even though a humidifier might smell like burning, it does not always pose a threat of causing fire.

All the same, do check out our article on Vicks humidifier smells like burning. You will see all the things to check.

How to remove the fish smell from the humidifier

If you have checked and ascertained there is no burning, no blown fuses, sockets, or power cords, try the following:

Clean the humidifier tank with bleach

Add a teaspoonful of bleach to a gallon of water, and add the water to the tank. Let it stay in the tank for 30 minutes, pour it out, and rinse thoroughly.

The smell of fish will be gone. If it still lingers, repeat the process. If there are mineral scales on the tank, clean them too, and scrub them out with a soft brush.

If you have been using demineralization cartridges, they too need to be soaked in the bleach-water solution, or replaced.

The same applies to filters. If you have a filterless humidifier, just clean the tank.

Why do humidifiers smell like mildew?

A humidifier carries stagnant water. Now, when that water stays too long in the tank, it becomes stale.

When that happens, you start to experience weird smells. These come from the mold and mildew that form inside the tank from the stagnant water.

If your humidifier smells like mildew, well, it is because there is mildew inside the tank. Therefore, you have to clean it out.

Unless a unit is clean, even adding essential oils in the humidifier to mask the smell will not help. The mildew will still come out with the mist.

Also, remember that where there is mildew, there is likely to be mold.

How to remove the mildew smell

  • Unplug the unit from power and pour out the water, preferably outside the house.
  • Mix a spoonful of bleach with a gallon of water, add the solution to the tank, and leave it for 30 minutes
  • Pour the water
  • Try to reach inside the humidifier tank, scrub the walls of the tank with a clean brush
  • Try harder to clean the evaporator belt if it has one
  • Remember to clean the base with a bleach-water solution. Ensure water doesn’t get into the circuitry
  • Rinse the tank thoroughly, reset it on the back of the base, fill it with distilled water, and run it

Why does my humidifier smell like it’s burning?

Why does my humidifier smell like it's burning

There are a few causes of the burning smell from a humidifier. The most common one is faulty electrical, including blown fuses.

Take the plug out of the socket and smell it. Does it smell burned? If yes, you have a blown fuse.

Go along the entire length of the power cord, smelling it. If you smell burning, smoke, or fish at any point, the cord is blown. It is just that you cannot see it through the insulating plastic casing.

Another reason for your unit smelling like burning is because of overheating electrical parts. Mostly, the blower motor is to blame for this.

If this happens, just switch the unit off, wait for it to cool down, and then clean it thoroughly. Actually, most of these problems occur because people neglect to clean the unit for too long.

Wiring issues in the circuitry could also cause a short-circuiting problem inside the unit. Generally, never take a burning smell from your humidifier or dehumidifier lightly.

How to solve

If you suspect there is short-circuiting in the circuitry wiring, contact the manufacturer if the humidifier is still under warranty.

If it is not under warranty, take it to a local repair shop so they can take a look at it.

If it is too old, just get rid of it and buy a new one.

It smells like cat pee

why does my humidifier smell like cat pee

Weird, but yes, sometimes a humidifier does smell like cat pee. If you have a cat litter box in the house, you will understand this kind of smell.

Your unit will smell like urine when you do not clean it or change the water frequently. It is a well-known fact that a large concentration of E. coli bacteria can have a pungent, urine-like smell.

Since the e Coli bacteria are all over the place, they can easily get into your humidifier tank. Because of the room temperature and the moist conditions, they find a perfect habitat to breed in.

How to remove cat pee smell from the humidifier

Once again, clean it often, after every use. If it has been in storage for some time, clean it before using it. This removes the smell of dust, and kills bacteria and mold that might have built a home in the unit.

Remember, most of the smell-causing organisms in the humidifiers and diffusers are not visible. That’s why it’s vital to keep to a 3-times-a-week cleaning schedule.

The humidifier smells sweet

sweet smell from humidifier

If you experience a distantly pleasant smell any time you switch on the humidifier, well, it is because it contains an activated carbon filter.

It is possible you could have bought it without being aware of this fact, but this is the age of advanced technology. Manufacturers are packing all manner of germ-capturing technologies into their products.

Usually, the filter has activated carbon. It will not only capture bacteria, mold spores, and minerals from the water, but it will also remove odors from your mist. It also removes the heavy metals from your water.

The activated carbon is responsible for producing a pleasant smell.

If you have a Boneco ultrasonic humidifier, you can order the BONECO AOS Hydro Cell A200 Humidifier Filter with Activated Carbon on to use with it.

Some activated carbon filters are universal, but before you use one in your humidifier, find out whether the manufacturer of your unit okays it.

Conclusion: Why does my humidifier smell?

From this short post, you can deduce the following reasons for your humidifier smelling:

  • Neglect: staying too long without cleaning the unit
  • Not changing the water as often as is needed
  • Using the humidifier without cleaning fresh from storage
  • It is new so it has a plastic smell
  • Bacteria, mold, and mineral buildup in the tank and the filters
  • Wiring problems in the cord or the circuitry

We hope this write-up helps. Mostly, apart from the burning smell, the rest are things you can solve on your own.