Informational Guide

How Often Do You Change a Humidifier Filter?

You may need to change it every month or may be able to wait as long as six months before changing your filter, depending on the type of humidifier you own.

by Josh M

Humidifier filters are an essential part of your humidifier unit. These filters work to capture minuscule particles and minimize mineral build-up in your machine.

In our guide, we will show you how often to change the humidifier filter so that you can keep your unit running smoothly.

  • To Trap Particles — Filters inside of a humidifier can help clean the air as an air purifier might. While the humidifier will not clean the air as thoroughly, it can help to get rid of pollen, dust, and other air particles. This helps clean the air while adding moisture to it.
  • For Mineral Absorption — In most humidifiers, hot and cool mist as well as evaporative units, the humidifier can trap mineral particles, including the dust that humidifiers often project. This dust comes out in a white dust form and creates problems with cleaning. Changing the filter often will help prevent this dust.
  • As A Wick — If you have an evaporative humidifier, then the filter acts as a wick. The filter helps to pick up and trap moisture that will then be flown out via the humidifier’s internal fan. These filters also have an antibacterial coating to keep bacteria out of your humidifier and your air.
White Humidifier on Top of Bedside Table with Books

When Should I Change My Humidifier Filter? (For Each Type)

Central/Whole House Humidifiers

Most central or whole house humidifiers are designed to be used daily. If you use your humidifier daily during the winter/heating season, then we recommend changing the filter once per season.

These humidifiers do not require much maintenance but are expensive to purchase and set up. This is the largest humidifier available, and the filters tend to be large (sometimes there are multiple filters in the unit). Replace the filter once per winter/heating season.

Cool Mist Or Hot Steam Humidifiers

A cool mist or hot steam humidifier should be replaced every 1-4 months depending on the type of humidifier and the brand. The tell-tale sign that the humidifier filter needs to be replaced is when the humidifier starts sputtering water, or you notice a foul smell.

You may also notice that the water is dirty or find more dust than usual in the room.

Ultrasonic Humidifiers

An ultrasonic humidifier filter should be replaced every three to six months and cleaned every one to two months. Many ultrasonic humidifiers have filters that can be cleaned once or twice before they are replaced.

An ultrasonic humidifier is convenient for homeowners and comes in both cool mist and hot steam models.

Furnace Humidifiers

A furnace humidifier filter should be replaced every winter/heating season. These tend to be whole house humidifiers. These units can be challenging to take apart, so you may want to hire an HVAC technician to replace your filter for you.

If the filter is easily accessible, then you can replace it on your own. These filters last for an entire season.


An evaporator humidifier should have its filter replaced every month or every heating/winter season. It depends on the size of the unit and the brand. Make sure that you check the manufacturer’s guidelines.

The evaporator humidifier is one of the cleanest humidifiers because it uses a fan system and a pre-moistened filter.

Humidifier for Good Sleep

How Often A Humidifier Filter Should Be Replaced (By Brand)

Always refer to the owner’s manual to determine how often you should change your humidifier filter as well as what steps you should take when changing the filter.


With Honeywell humidifiers, we recommend changing your filter approximately every 1-3 months. Honeywell specifically mentions the quality of the water in your home when making filter change recommendations.

If you have hard water with additional minerals, you will need to change your filter more often.


With Aircare humidifiers, we recommend changing the filter wick every 30-90 days. Aircare notes that hard water, as well as soft water, will lead to more frequent changes.

This is because both have minerals (soft water tends to have more salt, for example) and will need to be changed more frequently.


With Bionaire humidifiers, we recommend changing the filter every 2-4 months approximately. Again, hard water plays a role in how often you need to change the filter (the harder the water, the more often the change).

Bionaire recommends cleaning the humidifier with white vinegar to help remove mineral deposits that could cling to the filter.


With Aprilaire humidifiers, we recommend changing the filter every three months. However, if you have the 500, 600, or 700 models, then you only need to replace the humidifier each humidifier season.

Those units have specialized filters that can last longer and collect more mineral deposits before a replacement is necessary.


With Vicks humidifiers, we recommend cleaning the filter weekly and replacing it every 2-3 months. Some Vicks humidifiers do not have filters and are filterless. If you have a filterless Vicks humidifier, then you need to clean it weekly because mineral deposits are not being filtered out.

How To Change Humidifier Filter

When it is time to change your humidifier filter, follow these steps for a simple and effective filter change:

  1. .Make sure that you have a new filter ready. You can buy a cheap new humidifier filter on Amazon.
  2. .Start by turning off your humidifier. You don’t want the humidifier to be on when you are changing the filter.
  3. .Next, remove the front or top cover of your humidifier. Most units can be “popped” off, but you may need a small hardware tool.
  4. .Then, take the filter out. Once the filter is out, check the water tube and make sure that it is in the correct position. Now is a great time to clean the inside of the unit, including the filter tray. You can also check to see if the reservoir needs to be emptied.
  5. .Now, you can place the new filter in the unit along with the filter tray.
  6. .Finally, take the top cover or front cover of the humidifier and put it back on. You are now finished and can enjoy your humidifier again.
Brown Humidifier with Wood Design

People Also Ask (FAQ)

What happens if you don’t change the humidifier filter?

If you do not change your humidifier filter, then dust and dirt will build up over time. This will create mold in your humidifier. Mold particles can then be sent out into the air at your home. Your humidifier may also break down due to the lack of maintenance.

Can you clean humidifier filters?

You can clean your humidifier filter, but most filters should be completely replaced with a new filter. Filters are meant to be replaced, and the material cannot be fully washed and cleaned. Over time, the filter will have difficulty trapping particles.

How can I make my humidifier filter last longer?

The best way to make your humidifier filter last longer is to clean your humidifier unit consistently. Vacuuming the room that your humidifier is in will also help your humidifier last longer. If the room has fewer dust particles, then the humidifier will have fewer particles to trap. Cleaning the intake part of your humidifier will help avoid dust and dirt getting trapped and clogging the filter.

Can a dirty humidifier make you sick?

Yes, a dirty humidifier can make you sick because it can spread bacteria, mold, and mildew to the rest of your home through the water droplets it places back into the air. If you never clean your humidifier, then bacteria can grow, and mildew and mold can develop.

Why does my humidifier filter turn brown?

If your humidifier filters turn brown, then it is typically a sign that you have hard water in your home. Hard water turns filters brown because the filter is working to remove those minerals.

If you experience a brown filter, we recommend flipping the filter every two weeks and switching it out monthly.


Changing your humidifier filter is a critical part of maintaining your humidifier. We recommend changing your humidifier filter every three months.

You may need to change it every month or may be able to wait as long as six months before changing your filter, depending on the type of humidifier you own. Review your manufacturer instructions to make sure you change the filter on time.

Last Updated on December 20, 2022

Josh M

My name is Josh and I am obsessed with the HVAC industry. I created this website to help HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and home air products so you can learn & buy with confidence. Learn more about the team here.