Best Humidifier for Hard Water (Recommended by a Renowned Water Treatment Engineer)

Okay, you know that I am a meteorologist and that my area of expertise is air humidity. And, you also know that I am also a humidifier geek, right?


But, there's one thing you might not know.


When it comes to hard water and finding the best humidifier for hard water, I am not the best person to talk to.


That is why I decided to ask for an expert’s opinion.


And, who better to ask than a Water Treatment Engineer!


So, this post is going to be a bit different from the ones I usually do.


Namely, I will share with you an interview I’ve done with Antonio.


He is a Water Treatment Engineer that is working on building the Houston’s Water Purification Plant (which will, by the way, be the biggest facility of that sort in the world!).

I’ve asked him about what hard water is all about, how to deal with it, and which humidifiers are best for this type of water in his opinion.


Let’s see what he had to say.


best humidifier for hard water - interview graphic image
Leona Maurer

Leona Maurer


First of all, I would like to thank you for taking the time to answer a few questions, I am sure the readers will appreciate!

Thanks for having me, it will be my pleasure to help out.


Water Treatment Engineer

Leona Maurer

Leona Maurer


Okay, let’s start with HARD WATER. What is actually hard water and why is it different from, let’s say normal water?

Well, hard water is basically normal water, but with a few additions. For example, you just have heard someone saying "Water in my home is hard".


This means that they are dealing with regular water that has a high amount of dissolved minerals in it.


The exact minerals that make the water “hard” are magnesium and calcium.



Water Treatment Engineer

Leona Maurer

Leona Maurer


Is such water a health hazard?

Not really. It isn’t a health risk when those minerals are in the water.


However, it is quite a nuisance when it comes to washing clothes. The hard water cancels the effects of the detergent and the soap.


And, the mineral buildup will shorten the lifespan of your washing machine, dishwasher, fixtures, and what particularly interests you, humidifiers.




Water Treatment Engineer

Leona Maurer

Leona Maurer


You mentioned minerals, especially magnesium and calcium. How do they end up dissolved in the water in the first place?

Basically, it all comes down to air pollution. Namely, when the air is rich in carbon dioxide we get acidic waters.


This further means that when the water is acidic, it becomes an excellent solvent.


Now, as the water goes through rock and soil, small amounts of minerals dissolve.


And, they create a water-based solution that we know as the Hard water.


As I said, the main two minerals that actually make the water “hard” are magnesium and calcium. Both minerals are found in the soil and rocks.


The hardness levels of water increase as the amount of magnesium and calcium increase.


Water Treatment Engineer

Leona Maurer

Leona Maurer


How can we know if we have hard water and can we test it on our own?

Well, that is actually my job, isn’t it? (laughs).


To be honest, you can easily test the quality and hardness of the water you use. You can do it with DIY water testing kits. They are inexpensive and really easy to use.


I would recommend the DIY Testing for 10 Different Contaminants.


Or, you can try the DIY Testing for 20 Different Contaminants if you want to be really sure the water you use is hard or safe to drink for that matter.


And, one of my personal home testing kits, the Test Assured 10 Minute Testing.  This one is for testing the water for Lead Bacteria, Pesticide, Iron, Copper. But, it also detects more contaminants, such as magnesium and calcium.


Water Treatment Engineer

Leona Maurer

Leona Maurer


Okay, now that we have determined that our water is hard, how can we make it work with our humidifiers?

The truth is, you can’t make it work with a humidifier. At least not the ones that are advertised as “no filter” models.


I mean, they will work and produce the mist or vapor, depending on their mist output design.


But, minerals build up on the parts that are exposed to water, and this makes the humidifier break down quite fast.


However, this is actually not the biggest concern, the mineral buildup I mean.


The biggest problem with hard water for humidifiers is the minerals that reach the air you breathe.


And, if you remember, when they are in the water, it’s not that much of a problem.


It's just calcium layers on your teeth, which are removed with a 5-minute intervention by your dentist.


But, having these minerals freely floating in the air and reaching your lungs, is really not something you want to be exposed to.


Water Treatment Engineer

Leona Maurer

Leona Maurer


So, the best humidifier for hard water would be? 

Well, I can't simply tell you "The best humidifier for hard water is this model".


There are many humidifiers that can work great in such conditions.


But, what I can tell you is that I would recommend those that have either a filter or are based on the evaporative process and have a wick filter.


Models with high-quality filters and descalers will eliminate 99% of contaminants.


This includes calcium and magnesium.


On the other hand, the wick filter humidifiers will keep everything "stuck" in the wick filter.


Either way, both humidifier types are quite suitable for hard water use.


Water Treatment Engineer

Leona Maurer

Leona Maurer


Do you have a few models you prefer for hard water use and can you share them with our readers?

As a matter of fact, I do have a few models that I prefer.


I have actually done some research because of their ability to work without a problem when exposed to hard water.


I will need some time to name them all and tell everything I know about them, though (laughs).

Water treatment engineer


Water Treatment Engineer

Best Humidifier for Hard Water - The Expert's List

Here is the list of the best humidifier for hard water, actually, humidifiers. Antonio has 5 models that he considers as the best.

Best Humidifier for Hard Water (Expert's Choice #1) - Elechomes Ultrasonic Humidifier

Specific Features (Click here to know more)

The great thing about this humidifier is that it offers both cool and warm mist.


This means that if you catch a cold or flu during the summer, you can use the cool mist.


This will help you out with the dreadful symptoms.


On the other hand, during the cold, dry air winter months, you can switch to warm mist. This means cutting down on your heating bill but also making sure your home is free of airborne pathogens.


As for its tank size, you really won’t have to worry about refilling it too often.


This humidifier can hold up to 6 liters of water! What this means is 40 hours of continuous use and a mist coverage of up to 750 square feet.


And, thanks to an inbuilt humidity sensor, it won’t actually run all the time.


Once the desired humidity level is reached, it will switch to standby mode.


And, keep monitoring the humidity levels and turn back on if needed.




When it comes to hard water use, this is where this humidifier shines.


Thanks to its high-quality built-in filter, you don’t have to worry about airborne pathogens.


It will stop minerals such as magnesium and calcium reaching the air. And, it will also kill germs and prevent the forming of limescale.


Also, the filter has a long lifespan. And, this means lesser changing than with some other humidifier models.


Finally, the control panel is user-friendly and warns you if the water level in the tank is low. And, the humidifier even auto-shuts down before it gets completely empty.


So, you don’t have to worry about the dangerous “empty tank runs”.

Best Humidifier for Hard Water (Expert’s Choice #2) - Levoit Humidifier 4l

Specific Features

The first thing I have to highlight about this humidifier is that it comes with a two-stage filtration. There’s an active carbon filter that filters the air before it gets infused with the water mist.


And, there’s also a ceramic filter that filters the water before it reaches the nebulizer and gets turned into mist.


So, you really don’t have to worry if you are using hard water.


This humidifier not only cleans the water from minerals, but also from any other contaminant that might end up there.


Furthermore, this is a large-capacity humidifier. It can store up to 4 liters of water, and you have up to 30 hours of continuous use.


Also, the humidifier itself is whisper-quiet and the noise produced from by the nebulizer doesn’t go over 36 dB.


This means that you practically can’t hear it while working.


And, the humidifier is likewise easy to clean and maintain.


Also, it has an auto-shutoff feature. And, a very convenient night light which makes it suitable for use in a baby nursery as well.

Best Humidifier for Hard Water (Expert’s Choice #3) - Levoit Humidifier 5.5l

Specific Features (Click here to know more)

The same manufacturer as the previous model, only even bigger capacity water tank and more advanced features.


With this one, you also have both warm and cool mist options.


So, you can use it comfortably throughout the entire year.


For example, during the winter months, you can use it for preventing bacteria development thanks to the warm mist.


Also, it will help you with sinus flare-ups, cough, and irritated throat.


On the other hand, if you live in an area where the air is dry during the summer, the cool mist will help you with keeping your nasal passages moist.


And, your skin will also get proper hydration and stay healthy and smooth.


When it comes to tech specs, the mist output of this model is pretty high (450 ml per hour).


This means that your room will get moisturized quite quickly.


And, for better coverage, there’s a dual mist output.


As for the control panel, you will always have an insight into the current humidity levels in your room.


And, if you choose the auto mode, the humidifier will keep the humidity in the room constant on its own.


Of course, the humidity levels are fully adjustable.


And, you can choose the desired level and let the humidifier worry about that.



Another great feature that you get with this model is the possibility of adding essential oils to the aroma box.


You can turn your room into a spa and have relaxing aromatherapy sessions, anytime you want.


Finally, the humidifier is easy to maintain as the filter needs cleaning only twice a year.


And, this filter allows you to stay safe from the minerals that come from the hard water.

Best Humidifier for Hard Water (Expert’s Choice #4) - Honeywell Cool Mist Humidifier

Specific Features (Click here to know more)

Unlike the other models on the list, this one uses evaporation to humidify the room.


This means that it doesn't have a nebulizer.


In fact, it has a wick filter from which the water evaporates and gets pushed out with a fan.


This means that all the contaminants from the water stay on the wick filter.


And, this includes the main culprits for hard water, magnesium, and calcium.


The wick filter is also treated with Protec antimicrobial.


This addition prevents mold growth on the filter.



As for the water tank capacity, it can hold up to 3.7 liters (1 gallon).


This amount of water is enough for 36 hours of continuous use.


But, that goes only if you use minimum fan settings.


And, speaking of fan speed settings, there are 3 available speeds.


For example, on the highest speed setting, it can easily humidify a 250 square feet room.


Though, the tank will be empty after some 10 hours.

Best Humidifier for Hard Water (Expert's Choice #5) - Honeywell HCM350B Humidifier

Best Humidifier for Hard Water - Honeywell HCM350B Humidifier

Specific Features (Click here to know more)

This cool mist humidifier is another model from Honeywell and it also uses the evaporative process.


Again, the wick filter it comes with keeps all the minerals from entering the air you breathe.


Plus, this model comes with UV technology that kills all the germs and bacteria in the water.


The tank size is the same as with the previous model (3.7 liters, or 1 gallon).


But, when fully filled, you can expect a shorter working time.


This model can run up to 24 hours on the lowest fan speed, on one tank filling.


But, it’s powerful enough to comfortably humidify a bedroom, or a medium sized living room.


There’s no humidity sensor and you cannot set the humidity level.


However, if I’ve taught you anything, it’s the fact that you cannot over-humidify a room with evaporative humidifiers.


Once the humidity reaches 50-60%, the air will stop taking in the moisture from the wick.



To save energy and not run the humidifier unnecessarily, I suggest getting a hygrometer.


With this useful tool, you will always have an insight into the humidity levels.


Plus, you will know when to turn the humidifier off and save the energy.


This humidifier is great for the baby nursery, bedrooms, and when you are down with a cold or flu.


And, it really doesn’t matter if your water is hard.


Thanks to the wick filter, the minerals will not damage the humidifier nor will they find their way into the air.



With the last model from Antonio's list, we have reached the end of this guide.


So, what have we learned from this renowned water treatment engineer?


For starters, we now know how the why and how the minerals end up in the water we use and make it hard.


The main problem is actually air pollution and the levels of carbon dioxide.


The higher the levels of carbon dioxide in the air, the more acidic the waters are.


And, the more acidic the water gets, the more minerals it will dissolve on it's way to our homes.


Simple as that!


Now, when it comes to using hard water for humidifiers, you can make distilled water and purify it from calcium and magnesium.


But, the process takes too long and the amount of water you get is not nearly enough for even a one-night humidifier run.



The solution would be the best humidifier for hard water you can find on the market.


And, thanks to our water treatment expert, you now have a list of 5 best models.


The only thing you have to decide is whether you want to use a cool mist humidifier with a filter, or an evaporative model with a wick filter.


In both cases, you will be safe from the minerals and have a clean, healthy mist and ideal humidity levels in your home.


So, if you have some questions, don't be shy!


Visit the comments section below and feel free to ask anything that concerns you.


I will be happy to help out, and if I can't, Antonio will help me out 🙂


Thanks for reading and don't forget to share this post on social media.


Let's help other people find the best humidifier for hard water and deal with dry air or health issues, regardless of the hardness of the water they have.

6 thoughts on “Best Humidifier for Hard Water (Recommended by a Renowned Water Treatment Engineer)”

  1. Hi, I’m a working mom with 3 kids and I was thinking if honeywell HCM 350 humidifer is a good fit. When I searched online, there were mixed reviews about this ”germ-free” humidifier. Is it possible to do a review on this humidifier?

    • Hi Carol, thanks for a good question. Yes, I’ve also seen mixed reviews but honestly, I truly believe that the bad reviews come from people who don’t take care of their humidifiers. By taking care, I mean regular cleaning, washing the wick filter, and regular wick replacement. This really is a great humidifier that will keep all the impurities from the water stuck inside the wick filter, and, the UV light model also kills germs. As for the review of this model, I will actually test this model out and let you know my thoughts in the future!

  2. Hi Leona, I really loved this post and enjoyed reading it. Just wanted to ask you something. I was planning on buying the Vicks Ultrasonic Cool Mist Humidifier, but then I started doing some research and it turns out that people are complaining about the condensation on the outer surface of the tank and that it creates a watery mess around the humidifier. Would you by any chance do a review of that model? I would love to hear your thoughts on it. Thanks in advance and keep up the great work!

    • Hi Anna. Thanks for the nice words and I will try and keep up the good work. Now, as for the Vicks humidifier, I’ve also heard a lot of complaints, and I promise I will look into it. In fact, I know a fellow mommy blogger who already has one so you will get your Vicks impressions post sooner than you thought 😉

  3. Thanks for the thoughtful, fun article! I’ve gone through a lot of the Vicks-style models, the heating elements corrode in my water. Didn’t think of using distilled water, but that sounds pricey! As are wick filters – I read a review on Amazon that said they need replacing every 6 weeks and they cost over $5 each. Replacing burnt-out humidifiers costs more. Thanks for your tips, hopefully I can get a machine that works for us in Canada,

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