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What Type of Water Can You Use in A Humidifier?

by Dr. Jonathan Doyle - Updated June 07, 2023
We are all familiar with humidifiers and what they do. These devices are designed to make the surrounding space humid by releasing water vapor into space. Whether you have a warm mist humidifier, a wick-based humidifier, or an ultrasonic humidifier placed in your space, they all do the same job of turning liquid water into a vapor or a mist that stays in the air to increase humidity. All of these partly explain why about 8 million units are sold annually across America.

Why Do People Use Distilled Water in Humidifiers?

The involvement of water as the primary component of a humidifier also opens up the risk of mold and bacteria contamination, considering these harmful microorganisms thrive in moist environments.
Researchers at the University of Utah published a case study that discovered a severe lung injury in an infant breathing in a humidifier, “white dust.” The white dust is the powdery accumulation of magnesium, calcium, and other metal deposits that had settled in the water tank or reservoir of the humidifier. Inhaling these metals in the form of mist can be dangerous, with several short-term and long-term health implications. The National Environmental Education Foundation also advised against using humidifiers for children who have asthma.
a child is next to a humidifier, gazing at the mist coming out of it
A straightforward way to prevent the generation of harmful white dust, similar to what was reported in the previous study, will be to fill humidifiers with only distilled water. The Environmental Protection Agency (EPA) has also recommended using distilled water in humidifiers because the water has been boiled to inactivate most impurities, including bacteria and mold, ensuring the humidifier produces only a safe, healthy mist.

What Type of Water Is Suitable in The Event of Distilled Water Shortage?

Distilled water is a valuable type of water with tons of applications in essential industrial and chemical processes. While it is the most preferred option for humidifiers, its high value means it can be unavailable in some situations. In the event of distilled water shortage, the logical option would be to consider other readily available water sources. But is this safe?

Can you use tap water in a humidifier?

Most people would automatically consider tap water for humidifier because it is readily available. However, this is not a safe move, and even most manufacturers do not recommend the same. There are a few reasons for this. For example, tap water usually contains minerals like magnesium and calcium, which can form deposits inside the humidifier over time. Inhaling the resulting white dust or scale can cause respiratory irritation.
Tap water has also been found to contain microorganisms like fungi and bacteria and cleaning agents like chlorine and chloramine. Except the humidifier’s water tank or reservoir is regularly washed out using the right cleaning agents, these microorganisms can multiply over time and end up in the air as a component of the released mist. This can be another source of respiratory problems for people around.
For more information on the comparison between tap water, purified water, and distilled water, please refer to the blog: Purified vs Distilled vs Tap Water: What's The Difference?

Can you use bottled water in a humidifier?

Another option would be bottled water for humidifiers, considering it is readily available in most homes where tap water is not the primary source of drinking water. However, similar to tap water, bottled water is also not recommended for use in humidifiers.
The use of bottled water in humidifiers is expensive. An average humidifier requires a significant amount of water, and you will end up spending more over time. The varied quality of these bottled water brands also means some may contain minerals, additives, or impurities that can lead to mineral accumulation in the humidifier water tank. The risk is even greater for bottled spring water—it is known to contain high amounts of minerals and additives like flavorings and electrolytes that are originally intended for drinking.
bottled water on a display stand

Can you use purified water in a humidifier?

The suitability of purified water for humidifiers depends on a few factors.
The first is the purification process that produces the water. Some purification methods, such as the use of activated carbon and KDF, cannot remove hard water minerals like calcium and magnesium. Purified water filtered by your refrigerator and water pitcher falls into this category—the purification process does not remove limescale in some cases.
Similarly, water purified by ultrafiltration may be unsuitable because the process can only remove dissolved substances after first adsorbing them using activated carbon or coagulating them with iron salts or alum.
However, you can use purified water from a reverse osmosis filtration process. Reverse osmosis-filtered water is free from impurities, including minerals, bacteria, viruses, and other contaminants. The water also tends to have a very low mineral content compared to other water sources (usually 90-99% lower).

How Can You Make Tap Water Safe for Humidifiers?

If you can only access tap water, you should consider ways to make it safe for your humidifiers. There are multiple accounts of transforming tap water into distilled water at home by boiling the water in ways similar to the industrial distillation process. However, the downside to this is that the process is susceptible to contamination. So, what is the way out?

Install A Home Water Distiller

A home water distiller is a device designed to purify water by using the process of distillation. Water distillers for home typically consist of a heating element to boil the water, a condenser to collect the steam and convert it back into liquid form, and a storage container to hold the distilled water.
While using a home water distiller can be an effective way to purify water, there are some potential drawbacks associated with their use.
  • Higher cost: The initial investment for a distiller is typically higher due to the complexity of the distillation process and the equipment involved.
  • Contamination risks: It’s crucial to ensure that the distiller is clean and properly maintained to minimize this risk.
  • Energy consumption: Distillation requires heating water to its boiling point, which consumes a significant amount of energy.
  • Time-consuming process: Distillation is a time-consuming process, especially for larger quantities of water. It takes time to heat the water to the boiling point, collect and condense the steam, and produce the distilled water.
  • Maintenance requirements: Distillers require regular maintenance to ensure the proper functioning and to prevent the buildup of mineral deposits or scale.

Install A Reverse Osmosis Water Filtration System

The Waterdrop Reverse Osmosis System X12 offers a high-speed, tankless water filtration at an impressive 1200G with an 11-stage precision filtration mechanism, capable of removing contaminants such as lead, chlorine, and PFAS, while enhancing water with essential alkaline minerals like calcium and magnesium.
It not only improves health, taste of food and beverages, but can also alleviate stomach acid discomfort. Boasting a smart design, the system includes a digital faucet with functions such as precise water dispensing and TDS/filter lifespan monitoring. It's engineered for space-saving and simple DIY installation, re-mineralizing water to create natural-tasting, fresh, and healthy water accessible directly from your kitchen.
Installing reverse osmosis (RO) water filter system can help you obtain water suitable for your humidifier by removing impurities. The filtration process is highly effective at reducing most impurities in water, including chlorine, heavy metals, sediments, viruses, bacteria, and even dissolved solids.
The filtration process also significantly reduces mineral content, and this can be particularly useful for humidifiers. This minimizes the accumulation of minerals, and formation of scale, and the resulting release of white dust into the air. With the mineral content almost non-existent in the water, your humidifier will require less frequent cleaning and maintenance, thus increasing its lifespan. RO water filter systems can also remove bad taste and odor, ensuring your humidifier provides a more pleasant and refreshing humidification experience.
a little girl is drinking purified water obtained from a reverse osmosis water filter
Asides from the benefits it confers on your humidifiers, having a reverse osmosis water filter in your household means you can always access purified water for drinking and other household applications. In addition, the convenient and easily accessible source of high-quality water can improve your standard of living and keep you and your loved ones safe and healthy.

In Conclusion

Humidifiers can be unsafe depending on how it is used and maintained. The type of water you use is the most significant determining factor. Using the right water is the first step in ensuring a safe and efficient humidification experience. This blog has established the suitability (or otherwise) of the common water sources out there.
The best water source for an optimal purification experience remains distilled water. However, reverse osmosis filtered water is also perfect for all humidifiers in the absence of distilled water. Compared to distilled water and other water sources, RO water is readily available and convenient to access.
Another essential factor to consider is the maintenance of your humidifier. Cleaning and washing out your humidifier frequently are recommended. However, it is even more important to use suitable materials. For instance, using cleaning agents in washing out humidifiers is not recommended, especially after the 2011 humidifier disinfectant disaster that affected the patients of a South Korean hospital.


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