Everything You Need to Know About Water in Portable Air Conditioners

To keep things humming, you might have to add H20 to your AC

Woman sitting on the couch enjoying ac at home
Photo: fizkes / iStock / Getty Images Plus / Getty Images
Woman sitting on the couch enjoying ac at home
Photo: fizkes / iStock / Getty Images Plus / Getty Images
Emma Diehl
Written by Emma Diehl
Contributing Writer
Updated February 19, 2024

Highlights

  • Some portable air conditioners collect water and must be drained as often as every few hours or as little as once a month, based on humidity. 

  • Some people have evaporative air conditioners, many of which require you to periodically add water to them to work. 

  • Portable air conditioners are ideal to supplement existing AC or to cool a small room. 

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Want to keep your portable air conditioner working as efficiently as possible? Some models require you to add water, but others need to be drained periodically to cool your home. So, do you need to add or remove water from your portable air conditioner to keep things running? Here’s what you need to know about water in portable air conditioners. 

What Is a Portable Air Conditioner?

Portable air conditioner in a bedroom
Photo: KucherAV / iStock / Getty Images Plus / Getty Images

A portable air conditioner is a type of air conditioner that stands alone and requires minimal setup to cool a room. If you can’t install a window AC unit, you can use a portable air conditioner, which is easy to move from room to room. 

There are two main types of portable ACs: ventless and vented. While both types are portable, their maintenance needs are distinct. You need to add water to one model to keep it operational and remove water from the other to do the same.     

Ventless portable air conditioners are often called swamp coolers or evaporative air conditioners. These systems use a fan and water reservoir to disperse cool water into a room to decrease the temperature. Ventless portable air conditioners are ideal for warm, dry climates and need additional water to operate. 

Vented portable air conditioners have an exhaust hose that attaches to a window. These systems pull hot, humid air out of a room to cool the area. Because vented portable ACs remove moisture from the air, they’re better suited for hot, humid environments and require manual removal of water from their reservoir. 

Do You Put Water in a Portable Air Conditioner?

How ventless portable ACs work, with warm air being pulled through the cooling pads by the fan and producing cool air

If you have a ventless portable air conditioner, add water to keep things cool. The water reservoir is at the bottom of a ventless portable air conditioner. Depending on the model or size, the reservoir could hold anywhere from a few pints to a gallon of water.  

The frequency with which you have to add water to the reservoir varies based on the unit’s size, the exact model, and the room temperature. At least once a week (or every couple of days, if you run the system constantly), clean the water tank, wipe it out, and fill it with fresh water to avoid mold in the air conditioner.

Do I Need to Drain My Portable Air Conditioner?

Vented portable AC draining steps illustrated, including placing your unit onto a raised surface

If you have a vented portable air conditioner, you most likely need to drain the water periodically. Like a whole-home air conditioning system or a window AC unit, vented portable air conditioners pull moisture or water vapor from the air. This process decreases the heat and humidity in the space while releasing cooled, dehumidified air that brings the temperature down. 

Ever notice a window AC unit dripping outside? That’s the collected moisture from the air inside escaping. With a vented portable AC unit, the water pools in the appliance, meaning you’ll have to drain the unit occasionally to avoid mold buildup and keep the unit running. If you notice your vented portable air conditioner turning itself off, it may be because the reservoir is full and the unit can’t pull any more water from the air to cool things down. 

How often you need to empty water from your portable air conditioner depends on the unit’s size, how much you run it, and even how humid the room is. In an exceptionally hot, humid climate, your vented portable air conditioner might fill up once a day. But in drier climates, you may only need to empty the reservoir once a week or less. 

Not all vented portable air conditioners require draining. Check the user manual to confirm if your model collects water or not. 

Troubleshooting Portable Air Conditioner Problems

If things are heating up with your vented or ventless portable air conditioner, try these troubleshooting tips:

Are things still steamy? When the above troubleshooting doesn’t work, it may be time to call in the professionals and find a local air conditioning repair company.

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Learn more about our contributor
Emma Diehl
Written by Emma Diehl
Contributing Writer
Emma is an award-winning writer, editor, and journalist with a knack for tackling tricky topics around home improvement and finance. When she’s not writing about DIY, she’s living it—slowly updating her 100-year-old home. You can find more of her work on HomeLight, SoFi, Trustpilot, and Apartment Therapy.
Emma is an award-winning writer, editor, and journalist with a knack for tackling tricky topics around home improvement and finance. When she’s not writing about DIY, she’s living it—slowly updating her 100-year-old home. You can find more of her work on HomeLight, SoFi, Trustpilot, and Apartment Therapy.
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