Do Portable Air Conditioners Need To Be Drained? You’ll Be Surprised!

If you are thinking about purchasing a portable air conditioner or have just got your first brand-new one, you may wonder how much maintenance it requires. For example, does it need to be drained?

There is no one-size-fits-all answer to this question. While most portable air conditioners need to be drained on a regular basis, some fully self-evaporating models don’t produce drainage water in operation.

This is just a short answer. I will illustrate why a portable ac produces water and what happens if you don’t drain it in this post to help you understand this question better. 

Let’s dive in!

Why your portable air conditioner is producing water?

The reason why some portable ac requires to be drained is that it produces water during operation. 

Similar to a dehumidifier, a portable ac cools the air through condensation. When the warm and humid air in the room gets into the machine, it will pass through an evaporator coil that has refrigerant inside.

The refrigerant can absorb the heat in the air and lower the air temperature. Meanwhile, when the air temperature drops below the dew point, the moisture in the air will condense and convert from vapor to liquid. 

This is why your portable ac will produce water. The more humid the air is, the more water it will produce in unit time. Cooking, bathing, and other daily activities can make your device produce more water.

Where does the water go in portable AC?

Every portable ac will produce water, but where the collected water goes, decide if you need to drain it. That is to say, if your device can recycle the collected water or expel it in another way, it may not need to be drained anymore.

Regardless of the portable ac type, the condensate will first get into a condensate tray and then accumulate in the water reservoir. Since the tank will become full with time, you need to dump the water frequently, which is not a nice chore.

Manufacturers have strived to reduce the frequency of draining a portable ac. As technology advances, models nowadays are partially or fully self-evaporating portable ac, meaning that at least a part of condensate will re-evaporate and expel outside.

Some will make use of the water to cool the condenser coil, and the moisture will go out from the exhaust hose. Some will utilize dual vent hoses to allow more water vapor to evaporate. There are also some portable air conditioning units that have a misting system that turns water into mist and then sprays it out.

What happens if you don’t drain your portable air conditioner

Technically, a fully self-evaporating model doesn’t need to be drained unless the climate is extremely humid because all the moisture has been expelled through the exhaust vent. Therefore, nothing bad will happen if you don’t drain it.

However, if your portable ac doesn’t have this feature, you need to drain it frequently. Otherwise, you are going to deal with some complicated situations.

It will shut off

Not everybody has the time to dump the water in the condensate tank in time. Therefore, portable air conditioners often come with a built-in float switch that will shut off the machine when the tank is full. 

If you notice your portable ac is not cooling, it may have been turned off because of a full tank.

Some models have an indicator or an alarm to remind you to dump the water.

Water overflow

Occasionally, the float switch can get stuck or damaged. In this case, the water will overflow and leak from the ac, which may ruin your floor or carpet and cause other water damage.

It will not affect your machine in a short time but may cause metal corrosion if you leave it unattended for a long time. 

Mold growth

If you don’t drain your unit,  the stagnant water can be a breeding ground for bacteria and mold. 

It will not only leave black or brown stuff in the tank or tray but also promote mold growth in the coils and shorten the lifespan since mold spores can travel to other places in the machine.

What to do if you often forget to drain your portable air conditioner

Until now, you must have understood why most portable ac units need to be drained. If your model is not fully self-evaporating, but you don’t bother to dump the water manually,  you can drain the water through a hose or a pump.

Use a hose

By attaching a hose to the ac, the water can be drained continuously to the floor drain. Keep in mind that it relies on gravity to move water, so you should make sure it is at a higher level.

Use a pump

If finding a proper placement is difficult for you, using an external pump can solve your problem, which ensures that the water can move smoothly, even from down to up. 

Purchase a new fully self-evaporating portable ac

Some people don’t bother to set up the draining system and don’t want to drain the water at all. Under this circumstance, buying a fully self-evaporating portable ac is the ultimate solution.

However, when the weather is extremely humid, it will still collect a small amount of water that needs to be drained. Some manufacturers, like Delonghi, requires you to dump the water at the end of the season.


This post has discussed a lot of useful information about whether or not you need to drain a portable ac.

You should purchase a fully self-evaporating model to eliminate the need to drain the water. If not, you will dump the water every so often because the portable ac works by cooling and dehumidifying the air simultaneously. 

You can make this task easier by attaching a hose or using a pump.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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