How to Prevent Mold in a Humidifier

mold in a humidifier

A humidifier is no less than a blessing for homes with dry air. You don’t have itchy, flaky skin anymore, and your allergic symptoms are relieved. But that’s the case only if you maintain your humidifier.

If you neglect cleaning your humidifier, it can do the complete opposite and harm your health by developing mold inside itself.

This article will discuss how you can prevent mold in a humidifier and remedies to remove it. Read on!

Why Mold Appears in Humidifiers

The first reason is obvious. Mold loves warm and humid areas, and what’s better than the cozy and moist standing water in a humidifier’s tank? If you don’t change the water in the tank at least once every two days, mold and bacteria can quickly start breeding in there.

Mold growth also occurs because of the kind of water you use in a humidifier. While it’s convenient to use tap water, it can lead to residue buildup in the tank due to the minerals present in it. This mineral deposit acts as a food source for mold, enabling it to breed and contaminate the water.

Read Review: Best Humidifiers for Hard Water

How Dangerous are Mold Spores in a Humidifier

The short answer? Pretty dangerous. When a moldy humidifier sprays out water vapors, tons of mold spores enter the air along with them.

These spores can start breeding on whatever surface they find – carpets, furniture, wet towels, and even your lungs.

There’s a high chance you’ll breathe in the mold spores, causing you nasal discomfort. For some people, though, they can cause allergies and respiratory issues, such as:

  • Wheezing
  • Coughing
  • Throat irritation
  • Nasal congestion
  • Eye and skin irritation

Moreover, mold can trigger severe asthma attacks in asthma patients. Even for people who aren’t sensitive to mold, excessive exposure can cause neurological impairment over time, as proved by a study.

Read also: Common Household Mold Types

How to Prevent Mold in a Humidifier

Keeping those consequences in mind, it’s important to prevent mold in a humidifier before it has a chance to grow in it. Luckily, this isn’t hard to do:

  • Rinse the tank – depending on how often you use your humidifier, be sure to rinse the tank regularly. If you use your humidifier on a daily basis, rinse the tank and refill it with water every day.
  • Use distilled water – tap water in a humidifier is a big no-no. Not only will it cause mineral buildup and prevent your humidifier from working properly, but it will also encourage mold growth. Instead of tap water, use distilled water as it doesn’t contain any minerals or pathogens.
  • Descale – if you do happen to use tap water, be sure to descale the humidifier every week. This helps the humidifier stay clean and safe for use. Also, replace your humidifier’s filters every two months or even earlier. You can’t exactly descale a filter – it needs to be replaced.

You may also like: Best Air Purifier for Mold Spores

What to Put in a Humidifier to Prevent Mold

Preventing mold in a humidifier also requires proper disinfecting. Here’s how you can do it:

  • White vinegar – one of the easiest ways to clean the tank is by using white vinegar to humidifier water, which will kill bacteria and mold. Mix two cups of vinegar with one cup of water and pour this into the empty tank. Let it sit for 30 minutes or so. Next, scrub away any mineral buildups and rinse thoroughly.
  • Humidifier tablets – you can also drop in some humidifier/demineralization tablets into the water tank. This will prevent mineral deposits and mold growth in the water through ion exchange (people with heart diseases should use them with caution, though).
  • Bleach – for more powerful cleansing, use one teaspoon bleach in about one gallon of water. Alternatively, you can spray the insides of the tank with 3% undiluted hydrogen peroxide. Let the tank soak in it for 15 – 20 minutes before rinsing it out thoroughly. This will kill mold and also clean any residues.
  • Tea tree oil – a much milder yet effective way to prevent mold in a humidifier is by using tea tree essential oil. It’s a natural antibacterial agent, derived from leaves of an Australian tea tree. Add several drops of this into the water and let it dissolve. Tea tree oil is safe to inhale in small amounts and is even known to relieve flu symptoms.

Must read: Using Essential Oils in a Humidifier


It’s crucial to prevent mold in a humidifier to benefit from it. It may not be apparent at first, but mold can cause serious health issues, especially in children. Hence, regular cleaning, disinfecting, and using the right kind of water can help prevent moldy situations while keeping the air humid enough.