You can use tap water to fill your humidifier, but it's generally not recommended to use tap water directly for extended periods.  The best approach depends on the type of humidifier you have.

      I. Different humidifiers have different requirements for water quality.

1. Ultrasonic Humidifiers (Most Common)

Tap water is not recommended:

• Tap water contains minerals such as calcium and magnesium.

• This easily produces white powder (mineral deposits from the water).

• It can cause scaling, clog the atomizing plate, and shorten the lifespan of the device.

Recommended: Purified water / Distilled water / Softened water

2. Evaporative Humidifier (with humidifying filter)

Can use tap water

The filter can trap some impurities

However, the filter will accumulate scale and turn yellow over time

Suggestions:

Clean the water tank regularly

Replace the filter regularly, otherwise there will be unpleasant odors or decreased efficiency.

3. Heated (Steam) Humidifiers

Can use tap water

• High temperature kills bacteria

• However, limescale buildup is still a problem

Requires regular descaling

II. Why is it not recommended to use tap water for extended periods?

• Limescale buildup

Tap water contains minerals such as calcium and magnesium, which can easily cause limescale buildup in the water tank and on the atomizing plate, affecting humidification efficiency and lifespan.

• "White powder" phenomenon

Ultrasonic humidifiers atomize minerals along with the water, potentially leaving white powder on furniture and appliances.

• Bacteria and impurities

Although tap water is disinfected, it may still contain trace amounts of impurities.  Failure to clean the water tank regularly can lead to bacterial growth.

• Shortened lifespan of the entire unit and filter

• Unfriendly to air quality (especially ultrasonic humidifiers)

III. Recommended Water Usage Methods

• Purified water/deionized water: The ideal choice, virtually no scale buildup or white residue.

• Cooled boiled water: Better than direct tap water, reduces some impurities.

• Filtered water (e.g., from a water purifier): The effect is between tap water and purified water.

If you can only use tap water:

• Clean the water tank and atomizer regularly (1-2 times per week).

• Use with a humidifier-specific filter/descaling filter.

• Replace or thoroughly clean the unit when significant white powder or limescale appears.

Lazy person's solution: Boil tap water, then let it cool before using (this reduces some impurities).

Avoid: Tap water or bottled water that has been sitting for a long time (contains more minerals).

For short-term emergencies: Tap water can be used.

For long-term use: Direct use of tap water is not recommended.

Nanjing TC Tech Co.,Ltd. has been at the forefront of filtration innovation. We engineer the world's finest air purifier filters, humidifier filters and vacuum cleaner filters using cutting-edge technologies and materials. We aim at delivering clean, quality air to create the perfect environment for home and industry . Harnessing decades of expertise, our products push the boundaries of efficiency, performance and design. Our premium filters are trusted by various companies worldwide. With a commitment to constant R&D, we are advancing health, sustainability and quality of living for all. Our filters make the air you need.

Contact US:www.technjtc.com

Next article：Humidifier User Manual