Choosing the Right Humidifier
Step 1: Sonic or Evaporative?
There are two mains types of humidifiers: sonic and evaporative. Sonic models use agitators that vibrate at a supersonic frequency, jarring water molecules apart from one another and creating a fine mist. Evaporative models use a fan to blow air over a moist wick, which creates evaporation and an increase in humidity. These two technologies have different pros and cons, which we've outlined below. Sonic models are much more popular than their evaporative counterparts, largely due to lower prices and decreased maintenance, but evaporative models do have some benefits.
Pros and Cons of Sonic Models
Generally no filters required
Can cause over humidification if left unattended (some models have self regulating humidity meters to prevent this)
Can create 'humidifier dust' (dispersal of mineral deposits present in the water, can be mitigated by using filtered water)
Pros and Cons of Evaporative Models
Rate of evaporation naturally regulated by the ambient humidity - no over humidification
Mineral deposits get captured in wick - no humidifier dust
Requires buying replacement wicks
If not properly maintained wicks can become moldy
Louder than sonic models (about the volume of a small fan)
Sonic models can be damaged if they are left on after the water tank is empty. For this reason we only tested models that have an automatic off feature.
Step 2: How easy is it to clean?
Once you've chosen between sonic and evaporative technologies, the first thing you'll want to consider is how easy it is to clean. The importance of cleaning your humidifier can't be overstated, as breathing in mist from a moldy water tank can have very negative health consequences. We cleaned all of our models multiple times throughout our testing, so you can use our ease of cleaning scores as a guide, but generally you want something without any hard to reach nooks and crannies, and that comes with clear cleaning instructions from the manufacturer. For more of our thoughts on cleaning see the 'What Constitutes Proper Cleaning?' section below.
Step 3: Consider Over Humidification Challenges
As we mentioned above, over humidification is something you'll want to avoid. The best way to avoid over humidification depends on how you plan to use your humidifier. If you'll mostly use it when you're home during the day, you can simply monitor the humidity yourself, and adjust settings accordingly. If, like most people, you plan on running your humidifier when you're asleep or even when you're out of the house, there are a few different options.
The most inexpensive option is to simply buy a smaller humidifier. Our testing indicated that most of the smaller humidifiers (those that scored 5 or below on our humidifying performance testing) are unlikely to have enough power to over humidify most rooms. You should still be safe and start on a low setting until you get a feel for how the humidifier performs in the specific conditions of your home, but generally these smaller models won't cause condensation issues.
The major and obvious drawback of the above method is that you may end up with a humidifier that doesn't have enough power to get your room to your desired humidity. If you don't mind sinking a bit more money into obtaining a perfect humidity, you have two options. First, you can spend a bit more upfront and get a fully featured sonic model that includes a self regulating humidistat. Such a model actually monitors the ambient humidity and shuts off when it reaches the desired level. You can also get an evaporative model, which will not over humidify due to the natural characteristics of evaporation. This comes with the drawback of requiring replacement wicks for the lifetime of the unit.
Step 4: Consider the Water Tank
Besides regular cleaning, refilling the water tank is the most common and annoying chore associated with humidifier ownership. Having a large opening and a shape that can fit into a sink can make a huge difference. We mention these characteristics for each model under the user friendliness metric.
Step 5: Warm or Cool Mist?
Some of our humidifiers also have a warm mist option, which heats the water to create a steam. This has the slight advantage that the heat can kill some bacteria, but it by no means lets you off the hook for conducting regular cleaning. Therefore this is largely a personal preference, if you like the idea or warming up the cold winter air with some steam, then go for a model with a warm mist setting.
A Few Parting Thoughts
What Constitutes Proper Cleaning?
The short answer is whatever the manufacturer recommends. A quality humidifier will come with clear instructions as to how often and in what manner it should be cleaned. A general rule of thumb would be to clean the humidifier at least a couple times a week if you use it everyday, and to completely empty and dry the humidifier it will be left stagnant for more than a day.
Should You Use Filtered Water?
The Environmental Protection Agency (EPA) states, "The Federal government has not concluded that using tap water in ultrasonic or impeller humidifiers poses a serious health risk." It also notes that minerals in tap water can end up in the air you breath, can leave deposits in the water tank that can provide an opportunity for bacterial growth (again, cleaning is important), and can leave behind a white dust in your home. If any of these things concern you, you may want to use filtered or distilled water, or get an evaporative model that catches these minerals in a wick. You can read the EPA's humidifer suggestions yourself here.
We hope this article has cleared the mist from your path to a perfect humidifier. Take a look at our full review for our detailed thoughts and testing results from all of the models we reviewed. If you want more information on how we tested these products, check out our how we test article.