What Happens If I Leave Humidifier on Without Water?

Life is busy, so it is quite possible to forget to add water to the humidifier, but turn it on all the same.

Modern humidifiers like the Crane Drop Ultrasonic Cool Mist Humidifier are designed to shut down when they run out of water.

But the auto shut-off feature could fail. You could also be running an old model that doesn’t have one.

But really, what happens if you run a humidifier without water? Dry air will come out of the humidifier. People who forgot to add water to their humidifying appliances reported that dry air came out. There was no burning smell, no extra-loud noises, or anything untoward, except the dry air.

Keep reading to see how running a humidifier without water can affect it, and what you can expect.

1. The humidifier can shut down if you run it without water

Humidifier can shut down if you run it without water

In the first place, don’t even think about it. Really! Don’t. A humidifier uses water to add moisture into your indoor air. Therefore, it is designed to run on water.

A dehumidifier, on the other hand, is designed to suck moist air in, remove the water, and then blow the dry air out.

If the humidifier runs out of water, it is going to stop working. However, even if it continues to run, it is not going to do anything weird at all. It will not overheat, and it will not produce a burning smell.

For the humidifier’s safety and to remove anxiety from your mind, just get a humidifier with an auto shut-off feature.

There are many such humidifiers on different online marketplaces. Check these humidifiers that you can buy on amazon.com and other online marketplaces. 

2. A humidifier blows hot air if you run it without water

Let us, for a moment, consider how a humidifier works.

First, it sucks dry air in. It then moisturizes the air and uses a fan to blow the humid air out. How the humidifier moisturizes the air depends on its mechanism.

For example, an ultrasonic humidifier breaks water into very small particles with ultrasonic vibrations. It has a diaphragm for that.

It then releases these tiny water particles out into the air, whether they mix with the dry indoor air or make it humid enough.

You can see that when the humidifier tank is empty, it will not release any droplets of moisture into the air.

Your indoor air will continue to be dry. You will not enjoy the associated benefits of humidified air, as you can see on Medical News.

Can you run a humidifier without water?

Can you run a humidifier without water?

Water is the lifeblood and juice of a humidifier. Therefore, you should not even attempt to run it without water.

However, there are unusual cases of a humidifier running out of water and running for some time before switching off.

Also, in most cases, running a humidifier without water means running it until it uses all the water, leaving it completely dry.

This has its benefits. First, there will be no stagnant water left standing in the unit. Secondly, mold, bacteria, viruses, and gunk are not going to form.

Humidifiers can be super-spreaders of mold in the house. It is best to clean it as often as possible with white vinegar.  This kills the mold.

Even when you want the humidifier to be completely dry, you should not make a habit of running it too long without enough water. This can damage it.

What happens when the Vicks humidifier runs out of water?

What happens when Vicks humidifier runs out of water

Once a Vicks humidifier runs out of water, it is going to shut down automatically. It does this as a safety measure to prevent overheating.

And this does not apply to a Vicks humidifier alone. Rather, it happens with all other humidifiers on the market. Once they run out of water, they just shut down.

If you would like the humidifier to keep running for several hours, and you will not be around, set a low mist output.

That way, one gallon of water can help the humidifier make mist for up to 24 hours. Besides, a low mist setting ensures less water expenditure.

While you can run a Vicks humidifier without VapoPads, it is pretty hard to run it without water. The reason for this is that Vicks humidifiers are designed to go off when the water level runs too low. Therefore, it can be hard to run the humidifier due to bone dryness.

Unfortunately, the remaining amount of water will cause the formation of gunk, and bacteria and mold will thrive in the humidifier.

If you do not clean the humidifier thoroughly before running it, these allergens will be spread to your indoor air with the mist.

How long does it take for a humidifier to run out of water?

What happens when Vicks humidifier runs out of water

A humidifier will run out of water when it runs out of water! It can take a few to more than 24 hours for a humidifier to run out of water.

But that is not very helpful, right? Well, to put it another way, humidifiers are not the same. Some are big and some are small.

Some run on one-speed setting (mist output speed) and others run on two or three-speed settings. Here are some of the things that determine how fast a humidifier runs out of water:

The humidifier tank size

A 6-liter Levoit humidifier that you can buy on Amazon.com can last up to 24 hours running on a low mist setting. It can also run out of water in, say, about 12 hours of running on a medium-to-high mist setting.

A 2.2-liter AquaOasis™ Cool Mist Humidifier that you can buy on amazon.com can run for 24 hours on low-speed settings. Okay, it will run for a shorter time, but you get the general idea of how soon humidifiers run out of water.

If you live in a place that has really dry air day and night, such as Las Vegas, you need a high-capacity humidifier, one that can run for days without the tank running empty. Also, in such cases, a full-house humidifier is not a bad idea for people who live in very dry places.

The space rating of a humidifier

Before you order your humidifier from Amazon.com or other online marketplaces, you need to find out the space rating.

If you run a small humidifier in a large space, well, it is going to run out of water faster. At the same time, the humidifier is going to overwork or strain to increase the humidity. In any case, it has to run for hours to do the job.

A humidifier that’s rated for large spaces will have a large tank. One that is rated for a small space will have a small tank.

To buy the right humidifier, know the size of your room and buy one with a bigger space rating. It is better to go bigger than small.

However, remember that if a humidifier is too big for the space, it will humidify the air very fast and then shut down which might lead you to think something is wrong.

The mist output speed

Most modern humidifiers from Honeywell, Vicks, and other brand names come with up to three-speed settings.

On a low-speed setting, the humidifier water will run longer. Some can even run for several days before running out of water. You can almost enjoy the same benefits of a whole house humidifier.

The mist output that you choose for the humidifier will depend on a few things. For instance, if you want to increase the humidity in a room fast, set the highest mist output. This is very important when you have very dry air in the house.

If the humidity level is just moderately low, say, at 30 percent, and you want to raise it to 45 percent, medium to low mist output speed is going to work very well.

How to ensure your humidifier never runs out of water

You have seen what happens if a humidifier runs out of water. Nothing too weird, and nothing good at all. Therefore, take the initiative to ensure that your appliance always has water.

There are many ways to do that.

First, set a reminder on your phone. If you live in one of the driest cities in America, Italy, Australia, or anywhere else, set a reminder on the phone.

The alarm beeps, and it gives you the message of why you set it. You can then check the water level.

Clean the humidifier daily. If you make this a habit, you will also have to add water to the appliance daily.

Check the humidifier every day. This works, and eventually, it becomes second nature. Can you use a humidifier every day? You can. If it runs daily, you should check it daily.

Run Humidifier Without Water FAQ

If it is not yet clear just why this appliance really needs water, the following frequently asked questions regarding how to use your unit might help you:

Can a humidifier be used without water?

Never. Water is the lifeblood of a humidifying unit. Since this unit produces mist, it can only do so when there is water in the tank. Most units won’t even start to run if you switch them on when the tank is empty or absent.

Will an empty humidifier catch fire if it runs without water?

Your unit is made of plastic and electrical parts. Thus, if it does not have modern features such as an automatic shut-off function when it runs out of water, it is possible it can overheat, melt its plastic parts, and even catch fire.

Is it OK to use tap water in a humidifier?

It is perfectly okay, but it is recommended that you only use distilled water. Tap water has minerals, so it can lead to the formation of humidifier white dust.

Minerals in the water can also shorten the lifespan of your unit’s filters. Check the user manual of your unit to see what the manufacturer recommends.

How long does water last in a humidifier?

It depends on the size of your unit. For instance, a 3-gallon tank can run for up to 16 hours without requiring a refill. If you set high mist production, the running time will be shorter, and vice versa.


What happens if you run a humidifier without water? Nothing bad will happen to the humidifier.

Don’t sweat it too much if you forget to check the water level in the morning. However, you will have dry indoor air until you add water to the tank.