Do You Have to Use Distilled Water in a Humidifier?

Do You Have to Use Distilled Water in a HumidifierThis question “Do You Have to Use Distilled Water in a Humidifier?” comes up frequently. 

The short answer. It’s strongly advised so. Although some people use other water types, distilled water is by far the best option for humidification.

Simultaneously, though, we must mention that a few other water types, such as purified water, bottled water humidifier, boiled water, and demineralized water, can also be used in the humidifier. However, none of these can match distilled water. Distilled water is the purest form of water. It contains the least amounts of impurities. Therefore, it is the healthiest and safest for use in the humidifier.

In humidification, specifically, distilled water is often compared to tap water. There shouldn’t even be a comparison in the first place. Though safe for cooking and other uses in the home, tap water is the worst possible water type you can use in the humidifier. You’d be much better off using the other water types mentioned above (purified, bottled, boiled, etc.) rather than tap water.

Read on to learn why you should never use tap water in your humidifier, the process of distillation, and why distilled water makes an excellent choice for humidification.

Why Tap Water Bad for Humidification

All waters aren’t the same. The water you get from the well, from the tap and bottled water, may all be compounds of two hydrogen molecules and one hydrogen molecule. But, there are usually a few other elements in an ounce of water, ranging from dirt particles to untraceable microorganisms. These elements can make a massive difference during humidification.

Since tap water is the most accessible type of water in most homes, let’s look at some of the “foreign” particles that may be found in tap water at any one time.

According to the National Biology Library, tap water contains a range of chemical compounds, heavy metals, volatile organic compounds, pharmaceuticals, suspended solids, bacteria, and viruses. Three of these elements – chemical compounds, heavy metals, and bacteria/viruses are especially a risk when you use tap water for humidification.

  • Chemical compounds

Tap filters are designed to remove a large fraction of the chemical compounds found in tap water, but it’s impossible to remove all of these compounds through filtration alone. As a result, any tap water always contains traces of chlorine, chlorides, nitrates, sulfates, bicarbonates, phosphates, calcium, magnesium, sodium, potassium, lithium fluorides.

Not all these elements and compounds are harmful. However, when inhaled in large amounts, a few health issues can arise. Excessive exposure to fluorides, for instance, is linked to bone disease and parathyroid gland damage. Meanwhile, high sodium levels can increase blood pressure, while excessive nitrates can cause blue baby syndrome because of a lack of oxygen.

  • Heavy metals 

Tap water also contains significant amounts of heavy metals, including copper, lead, and arsenic. Most of these metals come from pollution sources such as industrial wastewater from mining, metal processing, and tanneries.

The accumulation of these metals can cause serious health problems. Inhaling too much lead and arsenic is directly related to central nervous system issues and problems in the lungs, kidneys, endocrine glands, bones, and cardiovascular system.

  • Bacteria and viruses 

Finally, and perhaps most worryingly, tap water contains a wide range of bacteria, viruses, and parasites (collectively known as pathogens). Viruses are the smallest form of microorganisms capable of causing disease, while bacteria are single-celled organisms that can also cause health complications such as sinus problems.

 Some of the common bacteria and viruses found in tap water in the US and North America in general include;

  • Legionella: Legionella is a bacteria that occurs naturally in the environment – typically in water. It particularly thrives in warm water. Legionella is a significant health risk if aerosolized, e.g., in a humidification system. It causes a type of pneumonia known as Legionnaires disease.
  • Enteroviruses: These are small viruses, such as polioviruses and echoviruses. They live in the infected human’s intestines. These viruses can cause an array of health issues, ranging from meningitis to gastroenteritis.

All tap water processing systems involve filtration that attempts to remove as many of these pathogens as possible. Unfortunately, it’s impossible to remove viruses and bacteria from water through filtration alone.

When you use tap water for humidification, the chemical compounds, heavy metals, and, worst of all, pathogens are released to the indoors together with the moisture. As such, people in the house end up inhaling the impurities, potentially causing health issues.

Read: Can You Put Hydrogen Peroxide in a Humidifier?

White Dust

Aside from breathing the impurities in the humidifier moisture, there’s another major problem when you use tap water for humidification – white dust!

White dust is caused by mineral content in the water that goes into the humidifier. It forms when mineral-laden moisture from the humidifier lands on your furniture and dries. Although the dust might seem harmless, it could be problematic for people with allergies, asthma, and other respiratory issues. White dust is also an unsightly mess.

According to one report whose findings have now been published on Research Gate, ultrasonic humidifiers are the main culprit. The percentage of aerosols formed by an ultrasonic humidifier in the respirable range is 90%. This is a massive concern because inhalation of aerosols emitted by humidifiers leads to the deposition of minerals present in the source water into the lungs.

The mineral deposits (white dust) contain traces of calcium and magnesium that can negatively impact human health, especially young children’s health. The dust exposes lung tissue to dissolved water constituents.

Why Distilled Water is a Great Alternative in Humidification

Water distillation is a process that turns water into steam to remove fluoride, arsenic, lead, viruses, and other contaminants. It imitates the earth’s natural water purification process. The result is clean water that’s safe for drinking, cooking and other household uses, such as humidification.

However, you need to understand the process, in detail, to truly appreciate the impact of distillation on water and why distilled water is much safer than tap water for humidifier use.

Distillation basically means converting water into vapor before condensing it and returning to a liquid state. During the evaporation process, solid impurities such as heavy metals, bacteria, and arsenic are eliminated because they cannot turn into vapor. As the water transitions to steam, these impurities are left boiling chamber. The distilled water then cools to a liquid state as mineral-free, crystal-clear water.

To begin the distillation process, water is poured into a boiling chamber in a special distiller. This boiling chamber is equipped with a heating element that raises the water’s temperature to a rolling boil. After reaching a certain temperature, the water evaporates, forming steam.

The top of the boiling chamber features a vent, through which the steam travels to a condenser chamber. Meanwhile, all particles that can’t turn to steam, including microorganisms such as bacteria and viruses, are left in the boiling chamber. The condenser is s stainless steel coil tube where the steam condenses back to liquid.

The condensation process is aided by a high-powered fan at the top of the distiller unit. The fan helps lower the distiller’s temperatures, forcing vapor from the boiling chamber to cool down into water droplets. These droplets then travel down a condenser tube and pass through a special carbon filter.

The purpose of the carbon filer (also known as carbon post-filter) is to remove persistent contaminants that may have traveled along with the steam to the condensation chamber. These often include volatile organic compounds (VOCs) with very low boiling points. VOCs readily turn into gases even at room temperatures. Therefore, they can easily escape with the steam to the condensation unit.

Read: The 7 Best Humidifiers Without Filters 

The activated carbon post-filters, through adsorption, easily eliminate VOCs and any other contaminants that may be present in the water droplets. After the filtration, the water exits the distiller and is collected in a stainless steel reservoir.

In a nutshell, the distillation process removes pretty much all the impurities we mentioned earlier from water, including;

  • Fluorides
  • Organic compounds
  • Dissolved salts
  • Solid particles
  • Lead
  • Heavy metals

The process also neutralizes all viruses and bacteria found in water as pathogenic microorganisms cannot withstand the high temperatures. Distillation also removes chlorine and chloramine that’s usually added to tap water. Although these minerals give taste to water, you don’t want to inhale them in large quantities.

The distillation process also removes contaminants such as nitrates, pharmaceuticals, barium, copper, arsenic, and iron. This effectively removes “water hardness.”

Boiling/Purification Can’t Match distillation

Finally, let’s close by debunking a common myth that boiled and purified water is just as good as distilled water. This isn’t true.

Boiling water is a great method of reducing the harmful pathogens that may be present in water. It’s effective in eliminating bacteria, cysts, and protozoa because these microorganisms cannot survive the high temperatures. However, the boiling process cannot remove chemicals, heavy metals, and dissolved solids present in water.

As for purification, the main difference with distillation is that purification doesn’t involve boiling, unlike the distillation process. Instead, it relies on other technologies, such as reverse osmosis and filtration. As such, purification, too, cannot match the thoroughness of the distillation process.


Distilled water isn’t the only type of water you can use in the humidifier. Purified water, bottled water, and boiled water, among others, are also fairly good candidates depending on where you live and the circumstances in which you find yourself. However, distilled water is, by far, the best type of water you can use in the humidifier. It’s essentially free of any impurities or any disease-causing microorganisms.


Photo of author
Melanie Mavery is an aspiring HVAC technician who is fascinated by the trends and opportunities in the HVAC industry. She spends most of her day writing content on home improvement topics and outreaching to prospects.  She's always looking for ways to support HVACs!