Why Do You Put Salt in a Humidifier?

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In recent years, the dividing line between humidifiers and vaporizers has become blurred, and even some manufacturers use both terms to describe the same unit. Traditionally, a vaporizer was defined as a device to produce steam by heating water, while a humidifier was defined as a device that produced a cool mist that relied on other means, such as physically throwing tiny droplets into the air. Today, however, there are vaporizers marketed as "warm mist humidifiers" or "steam vaporizer humidifiers" that combine features of both humidifiers and vaporizers. Whether you can safely add salt depends on the type of unit you own.



Never add salt, baking soda or any other ingredient to the water in your humidifier or vaporizer unless the manufacturer's instructions specifically state that it is acceptable to do so. Otherwise, you risk invalidating your warranty or damaging your unit, as salt can corrode the heating element, filter or seals. Using salt in a unit that is not designed for it or using more salt than the manufacturer recommends can create a fire hazard from overheating or excessive boiling. It can also trip the circuit breaker or blow a fuse.

The Benefits of Salt

Adding salt to water disrupts the bonds between water molecules and slightly raises the temperature at which the water will boil. At standard atmospheric pressure, the change in the boiling point is insignificant, amounting to approximately 0.555 degrees Fahrenheit, or 0.04 degrees Celsius. When impurities like salt are added to the water, the water molecules are forced further apart and can move about more freely, making it easier for the water to be converted to steam. The impurities improve the conductivity of the electrical current, but the impurity does not necessarily have to be salt, which is why some manufacturers recommend adding baking soda instead of salt or advise that if your tap water is "hard," adding salt is not necessary for the unit to function efficiently. Adding salt to a cool mist humidifier, such as an evaporative or ultrasonic type, will have no impact on the amount of mist that the humidifier produces because these models don't work by heating the water.


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How to Add Salt

If the manufacturer advises that you can safely add salt to your unit, follow its instructions carefully as the exact steps can vary by model. The basic steps, however, are relatively simple.

Step 1

Unplug the unit from the outlet.

Step 2

Remove the steam unit from the tank. Most steam units can be easily removed by twisting them to unlock them and then lifting them out.


Step 3

Add cool water to the mark or fill line shown on the tank. Do not use hot water and do not overfill.

Step 4

Add the amount of salt recommended by the manufacturer. Most manufacturers warn against using more than 1/8 teaspoon of salt. Some recommend starting with one or two pinches, then adding another pinch or two if the vapor is not sufficient.


Unless the manufacturer's instructions state otherwise, never use a total of more than 1/8 teaspoon of salt, which is roughly equivalent to four or five pinches.

Step 5

Mix thoroughly.

Step 6

Replace the steam unit and lock it into position.


Step 7

Position the unit in the desired location.

Step 8

Plug the unit into a wall outlet. You should not plug the unit into an extension cord.

Alternative Devices for Salt Therapy

Adding salt does not alter the steam's salt content. The salt molecules remain in the unit and will not be expelled with the steam. For those who are more interested in devices that provide breathable salt molecules, salt ionizers, ultrasonic salinizers and salt inhalers offer an alternative. Salt inhalers are designed for personal use, while most ionizers and salinizers can handle the air in one or more rooms. The degree to which these devices affect the humidity in the air varies by type, and some devices recommend the use of specialty salts, rather than common table salt.



Bill Goodwin

Bill Goodwin has more than three decades of experience in commercial, residential and industrial building maintenance and construction. He has been certified in refrigerant recovery, recycling and transition. Goodwin has been the author of numerous home improvement articles from 2008 to the present.