What is the Best Water for a Dehumdifier?

The good thing about any dehumidifier, be it a regular household model or a commercial dehumidifier, is that it is not picky when it comes to the water you put in it: since it does not produce mist like a humidifier, even tap water will do. 

However, for optimal ease of use, stress-free maintenance, and the overall longevity of the device, you need to know what the best water to use in a dehumidifier is.  

When you need to fill a reservoir (for pump-assisted or continuous-drain models), maintenance rinse, or top off a built-in bucket system, the type of water you use can affect performance and longevity.

Main Points

• Distilled water is the best for a dehumidifier, especially for long-term use.
• In the absence of distilled water, you can consider filtered water or tap water.
• Do not use rainwater, bottled water, or previously collected dehumidifier water.
• To ensure a steady supply of distilled water for home use, consider getting an affordable water distiller.

What is the Best Water for Your Dehumidifier?

Distilled water is generally considered to be the best water for a dehumidifier. This is because the process of distillation, through which distilled water goes, removes virtually all minerals, impurities, and contaminants.

For your dehumidifier, distilled water has the following advantages over other types of water, like filtered water and tap water:

•  No limescale buildup: Distilled water keeps coils, pumps, and tanks clean
• Better performance over time: It is least likely to cause clogging or leave any residue that may affect airflow
•  Less maintenance needed: With distilled water, your dehumidifier needs fewer deep clean sessions 
• Longer equipment lifespan: The internal components stay protected with distilled water
• Cleaner, odor-free tank environment: Since there are fewer places for bacteria to grow, a dehumidifier using distilled water is overall cleaner and odor-free.

All in all, distilled water helps your dehumidifier run smoothly, last longer, and stay cleaner with minimal effort on your part.

Tap Water vs. Distilled Water For Dehumidifier: What’s the Real Difference?

Most people default to tap water when it comes to choosing what water to put in a dehumidifier, and that’s perfectly acceptable. Tap water works too.

However, tap water is not the best water for a dehumidifier because, very often, it still contains minerals like calcium and magnesium, especially if your tap water is “hard. These minerals are a problem for a dehumidifier because they just disappear. 

Over time, these minerals within the tap water can harm a dehumidifier by:

• Sticking to internal parts
• Causing limescale buildup
• Slowing down its performance
• Causing the dehumidifier to smell bad or encouraging bacterial growth
• Even shortening the lifespan of the unit

This is where distilled water takes the spotlight. Compared to tap water, distilled water is a better and safer choice if you want to protect your unit, keep cleaning to a minimum, and keep it running for longer.

What Types of Water Can (or Can’t) Be Used in a Dehumidifier?

The most common types of water for dehumidifiers are tap water, distilled water, and filtered water. However, some people also consider other types of water, like rainwater, bottled mineral water, and previously collected dehumidifier water. 

Here’s how these common types of water people consider ranked from best to worst (to be avoided)

Water Types You Should Definitely Avoid in a Dehumidifier?

There are three main types of water you should always avoid using in a dehumidifier, as they still contain minerals, dirt, dust, and other materials that are unsafe for a dehumidifier:

1. Bottled mineral water: packed with minerals that can clog and damage your system
2. Rainwater: can contain dirt, pollutants, mold spores, or bacteria
3. Dehumidifier condensate (water collected in the tank): Dehumidifier condensate isn’t clean; it contains airborne impurities and should never be reused inside the unit

How To Ensure a Constant Supply of Water for Your Dehumidifier

Though many people agree that distilled water is the best water for a dehumidifier, tap water still remains the most common type of water for a dehumidifier. Why? Because distilled water is expensive. A 5L bottle of distilled water costs about $10, and if you find yourself in constant need of distilled water for a dehumidifier, that is a lot of money. 

So, what can you do? One smart option is to consider purchasing a water distiller. A 4L water distiller costs about $90, but will serve you for a very long time, considerably lowering costs in the long run.

Frequently Asked Questions (FAQ)

1. Do I absolutely need to use distilled water?

Not necessarily. Tap water is fine in most cases, but distilled water helps protect your unit and minimize maintenance.

2. What happens if I keep using tap water long-term?

Over time, minerals may form limescale inside the unit, which can reduce efficiency and shorten the lifespan.

3. Can I use softened tap water?

Yes, but keep in mind that some softened water still contains minerals—cleaning may still be necessary.

4. Is rainwater safe for dehumidifiers?

Not recommended. It may contain pollutants, dirt, or bacteria that can contaminate the tank.

5. Can I reuse the water collected by the dehumidifier?

No. This water contains dust, microbes, and airborne contaminants and should not be put back into the system.

Final Thoughts

A dehumidifier is an investment in your comfort and air quality-so giving it clean, mineral-free water (like distilled water) helps it work more efficiently and last longer.

Whether you’re filling a built-in reservoir, rinsing components, or topping off a pump system, choosing the right water can make maintenance easier and your dehumidifier experience smoother.

You may also be interested in this guide on how to choose the right dehumidifier for a crawl space.