Why is My Humidifier Spitting Out Water?

There are various reasons why your humidifier could be spitting out water. We will have a look at how you can troubleshoot each cause, and also discuss tips on how to prevent this issue.

Humidifiers aren’t complicated devices. And, they rarely need maintenance – apart from regular cleaning and filter replacement.

That said, they do occasionally have problems – and one of the more common ones, is they start spitting out water.

When a humidifier functions optimally, it releases water in the form of steam or vapor. If your humidifier is spitting out water, this could be a reason for concern.

Keep reading if you want to learn the following:

  • What adding salt does to your humidifier
  • What happens when you add too much water
  • What your incoming water pressure may have to do with the problem
  • The effects of mineral deposits
  • The effect of a blocked evaporator pad
  • The effect of low power

Adding salt to your humidifier’s water reservoir

For most humidifier manufacturers, adding salt is a no-no. Typically, they recommend filling the reservoir of your humidifier with distilled water. 

However, if you are using a unit that employs vaporizer technology, and if you’re filling it with tap water, adding some salt will certainly help if it isn’t producing enough steam. 

That’s the standard exception to the distilled water recommendation.

But, if you’re adding too much salt, the inevitable result will be a spitting humidifier. And, in this case, you’ll also notice a definite decline in the unit’s ability to produce steam.

Different technologies are employed in humidifiers. Some units use cold water and release fine water vapor into the atmosphere. Others first heat the water and then release steam. In the latter case, it is the carbon electrons connected to the electricity supply that heat the water.

Distilled water, as recommended by suppliers, is not conductive. In this case, adding salt is the go-to method to increase conductivity, and provide the extra power to heat the water and produce steam.

But – and here’s the critical BUT – when the increased power you achieve by adding salt exceeds the steam requirement, your humidifier will start spitting out water.

Refilling the reservoir with too much water

An over-filled water tank is often a reason for humidifiers spitting out water. Not only that, but it may also cause leakage

In an evaporative humidifier – in other words, a unit that heats water to cause steam, the water will bubble, and too much water will cause your humidifier to start spitting water.

Always make sure you don’t fill the reservoir beyond the water line mark on the tank’s outer surface.

The incoming water pressure is too high

In the case of a whole-house humidifier, increased water pressure could cause the system to start spitting water. 

Remember, whole-house humidifiers get water directly from the main water supply to your home. The pressure of this waterline should never exceed 125psi. If it does, and it consequently forces its way through the cutoff valve, your humidifier will overfill, and start spitting water.

Mineral deposits

Another typical cause if your humidifier is spitting out water, is the possible accumulation of mineral deposits, especially on the heating elements.

These deposits prevent the humidifier from producing steam in a steady flow, and this leads to the unit spitting water drops, instead of releasing steam vapor.

Your evaporator pad is blocked

Humidifiers can constantly produce clean vapor because dirt and bacteria are trapped in their filters. If the filter is blocked, your humidifier will naturally start spitting water.

Whole house humidifiers can pick up the same problem. In this case, the humidifier produces steam, which it blows across an evaporator filter pad.

Mineral deposits, as well as debris from the minerals in tap water, accumulate and clog the filter over time. This causes the drain to overflow and floods the coil and tank chamber.

As soon as this happens, the humidifier will release water through any available opening, including the mist nozzle. The result is a humidifier that starts spitting water.

The humidifier’s power is too low

A bubbling or gurgling sound when the humidifier’s base draws its water supply from the reservoir is quite natural. Provided the sound is low level.

However, this sound could also indicate that the power is inadequate. The result of low power is that the water will collect in the atomizer head of your unit.

In this case, the unit isn’t powerful enough to vaporize the water at an adequate rate, and this causes your humidifier to start spitting water and making an overtly bubbling sound.

This is because the machine doesn’t have enough power to vaporize the water quickly enough, thus flooding your coil and causing a bubbling or spitting noise.

There are several ways to stop your humidifier from spitting water

Now that we’ve touched on the more common reasons your humidifier may be spitting water, it is easy enough to troubleshoot the problem. 

Remember, though, the first step in your troubleshooting exercise is ALWAYS to unplug the unit first.

From there, finding the fault and fixing the issue is fairly simple.

If you’re using salt, make sure to add the correct amount

Under normal circumstances, one or two pinches of salt are more than adequate for your humidifier to produce a steady mist.

However, it does pay to follow the manufacturer’s recommendations as far as possible. And also remember – the salt content in tap water is not always stable. Water from your home’s main water supply may, at times, contain more salt than at other times.

It’s up to you to experiment. But making sure you don’t over-salt the water in the reservoir may very well prevent your humidifier from spitting water.

Make sure to drain excess water

Once you’re sure you are adding the correct amount of salt, and your humidifier continues to spit water, the water level is your next port of call.

Unplug the humidifier and allow it to cool. Disconnect the water reservoir, and make sure it is properly drained.

Most humidifiers have a water line that prevents overflowing.

When you’re sure your unit is properly drained, refill it to the correct level, plug it in, and run it for a while to see if it is still spitting water.

Clean your humidifier to get rid of buildup

Hard water, in other words, tap water with high concentrations of minerals, will create more power. This is because the minerals increase the conductivity of the electrons in the water. 

If there are too many minerals present in your water supply, these minerals will build up in the reservoir. 

Once this happens, your humidifier will continue to spit water even if you switch to bottled or distilled water.

The answer is to make sure you clean your unit at least once a week to remove traces of buildup.

A simple vinegar solution when cleaning, should unclog everything and prevent your humidifier from spitting water.

A regular filter change could help

Your water quality will determine how regularly you need to change the filter in your humidifier.

Your owner’s manual should tell you which types of filters to use in your unit. In some cases, you can clean and reuse filters, but in most instances, they need to be replaced.

A clean filter will often prevent your humidifier from spitting water.

In the case of a whole-house humidifier in daily use, for example, in winter, the filter should be changed at least once during the season.

Similarly, if you live in an area with excessively hard water, more regular filter changes are required to get rid of the mineral deposits.

A general rule of thumb is to change the filter when you break out the unit at the beginning of the season.

In the case of portable units, filter changes once every three months should suffice. If you use it every day, make that once every two months.

Remember, draining the unit completely when you change the filter, is also important to prevent bacterial and mold growth.

All of this should prevent your humidifier from spitting water.

Switch to distilled or filtered water

Tap water quality varies greatly. Demineralized, purified, or distilled water remains the best option for humidifiers. 

Hard tap water with higher concentrations of mineral salts, will inevitably cause your humidifier to spit water.

Make sure your water pressure is optimal

If you’re using a whole-house humidifier, check the water pressure. Anything higher than 125psi – call a plumber to install a pressure-reducing device on the supply line.

If this is the problem, your humidifier will immediately stop spitting water.

Possible electrical issues

If you suspect your humidifier is spitting water because of low power, test the power source.

Unplug your unit, and test the outlet with another electrical appliance. If the second appliance works according to spec, your humidifier may require professional repair.

If the other appliance doesn’t work properly, the power source could be behind your humidifier spitting water. In this case, a professional electrician is your answer.


As you can gather, the reasons your humidifier may be spitting water, are numerous. There are simple fixes, and things to be aware of when you maintain the unit. Most of these will be more than ample to prevent the issue.

If you make sure you’re adding the correct amount of salt to the water, or you switch to purified, demineralized, or distilled water, that may very well be half the battle won. Cleaning your unit regularly will certainly help to prevent problems, and a good clean may also solve the problem of your humidifier spitting water. Regular filter changes, and ensuring your humidifier isn’t overfilled at any point, will also prevent spitting. 

Bigger issues such as water pressure of more than 125psi, or low power, may require calling a plumber or electrician.

In most instances, when your humidifier starts spitting water, the problem is easily solved. Maintain it well, and you will get many years of happy service from most units.


Shawn Willis is all about humidifiers. After working for some of the biggest names in the industry, he started HumidifierGuys with Scott Dawson. Now, the dynamic duo helps others figure out what they need in their next humidifier.

Shawn is an avid sports fan, motorcycle enthusiast, and has two dogs named Whiskey and Boba.