air humidifier filter close up

Humidifiers work wonders for people that live in dry climates and want a more comfortable environment. But humidifiers require regular maintenance, like replacing or cleaning the filter periodically, what’s the ideal schedule for that? To help you recognize when to give your filter a little TLC, read this guide that explains how to tell if a humidifier filter is bad and the best way to maintain it.

What Does the Filter Do?

The filter removes impurities and particles from the water before the humidifier disperses the water into the air.

Tap water has many impurities, from copper, lead, and iron to chlorine and fluoride. The filter removes these substances from the water and then sprays the filtered water into the air to raise the humidity levels.

Types of Filters

There are two types of humidifier filters:

  • Wick
  • Netted

The two filters basically work the same; they’re different in shape and size. A wick filter is a thick cylinder that acts like a sponge. The netted filter looks like a stack of napkins, a rectangle of thin layers of net.

Filter Lifetimes

A regularly used humidifier filter needs replacing at least once every three months, and no less. The filter can only do its job with firm layers to block particles. Over time, these layers and nettings break down from wear and wind up, letting impurities slip through and disperse into your air.

The best practice is to replace or clean your filter once a month. Replaceable filters are often cleaner than reusable filters if you aren’t sure which you prefer.

Signs You Need a New Filter


If you notice your filter is turning yellow or brown, it is likely full of impurities and needs replacing or thoroughly cleaned until the color dissipates. The build-up and residue prevent the filter from properly doing its job, so there’s no point in continuing to use a filter like this.


If the filter has a pungent odor, it likely needs to be replaced. The odor can come from scaling, mold, or residue build-up. The smell will be musty like a wet basement or have a vinegar-like smell. These scents signal that you need to change the filter as soon as possible.


This is the most obvious one, but if your filter has any holes or rips in it, it needs to be replaced immediately. Even if they are caused by you, like if you accidentally rip it while rinsing it. Once the filter is compromised in this way, it can no longer filter the water.

Mineral Build-Up

You should clean your filter at least weekly to keep it working. Cleaning the filter removes minerals trapped, so it won’t be damaged by the remaining particles.

If you want to be diligent, you can gently rinse the filter every day to remove the minerals.

Tips to Help Your Filter Last Longer

how to tell if a humidifier filter is bad
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Replace Water Often

The longer the water sits in the tank, the more impure it becomes, collecting dirt, dust, and debris from the air. Changing the water as often as possible means your filter doesn’t need to work as hard to sift out particles.

Use Pure Water

Many people pour tap water from the sink into their humidifiers. This isn’t the worst thing, but it will be harsher on your filter, causing it to wear down faster.

Use either distilled or filtered water in your humidifier to help the filter last longer and prevent impurities from dispersing into your breathing air.

Monitor Humidity Setting

The ideal humidity for indoor space is between %30 and %50. Always set your humidifier in this range. If you set your humidifier to produce %60 relative humidity or higher, your filter has to work extra hard to remove particles from all the extra water.

If you keep the space very humid, your humidifier filter works harder and will wear out much faster.

Remove and Clean to Store

If you are storing your humidifier away, you need to remove, clean, and store the filter properly. Some people only use their humidifiers in the warm months, so they put them away come fall. But before storing the humidifier, it should be cleaned, including the filter.

Clean the filter and let it fully air dry before storing it, and don’t store it inside the humidifier. It should be stored beside it or on top of it so it stays fresh and clean for the next time the humidifier is used.

Optimize Use

If you leave your humidifier on 24/7, that’s fine, but it will result in filters that wear out quickly and need replacements more often. If you want to save money on filters, you can keep the humidifier on only when you’re home or when the air feels dry. Turning off the humidifier intermittently gives the filter a break from the harshness of particles to pass through.

Don’t spare the filter to suffer through humidity, this defeats the purpose of the appliance. But if you’re blowing through filters at an alarming rate, consider giving the humidifier a break every once in a while.

Bottom Line

The key takeaway of this guide is that you need to monitor your filter for wear and tear. If you don’t regularly change the water, rinse the filter and clean the unit, you won’t even realize when your filter has run its course.

Now that you have a better grasp on your humidifier filter, you should feel more confident in caring for the appliance and keeping your air clean and healthy.


Do I need a filter?

You don’t have to have a filter in your humidifier. Of course, it’s recommended by manufacturers, and by us. But there are ways to successfully operate a humidifier without a filter, even if it is meant to have a filter.

What’s the best kind of filter?

Best Air filters are the most popular filters for humidifiers; they remove the most particles from the water before spraying. If you want to purify and cleanse your air beyond just adding moisture to it, consider buying an air purifier and using high-rated HEPA filters to clean your air.