How to Drain a Portable Air Conditioner [3 Ways Explained]

Written by: Paul Cathro

Updated on: December 23, 2022

Portable air conditioner against a wall

Portable air conditioners need draining because they produce water when moisture in the air condenses on the cold coil. 

In highly humid environments, portable air conditioners produce three to four pints of water per hour - and it all must go somewhere!

While some air conditioners have self-evaporating technology and reuse moisture in the cooling process, even these collect water over time. Simply put, there isn’t a portable AC in the world that doesn’t need draining.

Thankfully, draining a portable AC is easy, and there are three main ways to do it. This article explains all. 

How to Drain Portable AC

You can drain a portable air conditioner in three ways:

  • Manually – where you empty the drainage tank 
  • Automatically with the exhaust hose – where water is expelled as vapor 
  • Automatically with a drainage hose – where water is pumped to a drain or sink 

It’s crucial to note that automatic drainage methods are model-dependent – not all portable air conditioners drain the same way. 

Also, each method has pros and cons.

For example, while both types of automatic drainage make life easier, manual drainage lets you move the portable AC around because the drainage hose or exhaust doesn’t tether you to a drainage point (a window or sink for example).

Method 1: Manual Drainage

Manual drainage involves emptying the contents of the condensate tank by removing the plug and letting the water flow into a bucket or pan. 

While manually draining a portable air conditioner is inconvenient, it untethers you from a drainage point, letting you move the portable AC around your house. 

In dry climates (less than 30% RH), you will empty the drainage tank every few days, but in high humidity (over 70% RH), you may find it fills very quickly and you might need to empty it every few hours.

Your portable air conditioner will have a non-removable or removable condensate tank. A removable tank makes life easier, but with non-removable tanks, you can squeeze a shallow pan under the unit so you don’t have to lift it into the sink. 

Pros and Cons of Manual Drainage 


  • No drainage point required
  • No chance of drainage hose leaks 
  • Move the unit around freely
  • Minimal draining in low humidity


  • Manual emptying
  • High humidity means hourly emptying
  • Downtime when condensate tank is full

Method 2: Draining via the Exhaust Hose (Self-Evaporative)

Draining via the exhaust hose is an automatic process exclusive to ‘self-evaporative’ portable air conditioners.

With self-evaporative technology, a bigger percentage of moisture in the air is expelled via the exhaust hose. Some of the moisture on the coils is vaporized and used in the cooling process, reducing water production.  

However, the technology is not 100% efficient – you can still expect water to drip into the condensate tank, albeit reduced. In humid environments, you can expect it to slash water production by around half.

Self-evaporative air conditioners cost +20% more than regular ones, but the convenience of not having to drain them often is a massive boon.

Because water and air are expelled from one hose, this also simplifies installation and reduces components and leak points in the system.

Pros and Cons of Exhaust Hose Drainage


  • It reduces water production
  • No need for a drainage hose/point
  • It doesn’t use significantly more energy
  • It eliminates the need for manual drainage in low humidity


  • More expensive to run
  • It can’t evaporate all moisture in humid environments

Method 3: Draining via Drainage Hose

Draining via a drainage hose is the most popular option for portable air conditioners because it’s reliable and easy to set up.  

In this method, a drainage hose connects to the condensate tank plug point, removing any water that drips into the tank to outside the system.

You can put the drainage hose into a sink, through an external wall, so it drips outside, or into a large bucket for manual emptying. The beauty of this method is you can run the hose internally or externally to suit your house.

However, there are two main types of hose draining, and you need to be careful when buying a portable AC to get the right type:

  • Gravity drainage requires the drainage hose to sit lower than the portable AC so that water flows down the hose with gravity.
  • Condensate pump drainage – a pump sucks water out of the tank, allowing the drainage hose to sit higher than the portable AC.

Which is best for you depends on where your portable AC sits relative to the drainage hose – if the hose is higher, go for a condensate pump. It certainly gives you more options.

Pros and Cons of a Drainage Hose


  • Reliable
  • No need for manual drainage
  • Works automatically
  • Works perfectly in high humidity


  • The drainage hose takes up space & can be unsightly
  • Condensate pumps can be loud
  • Gravity drainage requires careful planning & placement

Why Does a Portable Air Conditioner Need Draining?

Portable air conditioners produce water when moisture in the air condenses on the cold coils, and that water then runs down the coils into the condensate tank or evaporates and is expelled through the exhaust hose. 

If you don’t drain your portable AC, a few things can happen:

Interrupted Cycles 

The obvious reason portable air conditioners need draining is so the condensate tank doesn’t overflow and spill all over the floor.

However, a float switch stops this by switching the unit off when the tank is full, so spillage rarely happens.  

The real reason you need to drain a portable air conditioner is so that it continues to function interrupted. The float switch pauses your portable AC until you empty it – so draining it ensures it continues cycling.  

If you don’t drain your portable air conditioner, it will stop working when the tank is full, so you need to drain it for it to work.  

Having your AC stop prematurely is annoying and it's also bad for your energy bills, as it will need to work hard to "catch up" once it starts again.

We have a great guide that explains AC cycle lengths in detail.

Reduced Performance 

Periods of downtime increase humidity in your space, making your portable AC work harder when switched on. This reduces system performance and increases component wear, which can reduce your portable air conditioner’s lifespan

It is best to run your portable air conditioner on cycles to maximize performance and keep your space at a comfortable temperature. 

Mold Can Grow in the Tank

Stagnant water will grow mold which can permanently etch the tank, so it’s crucial to drain your portable AC before periods of downtime. 

Leaving water inside your portable air conditioner also increases the chances of leaks, reducing drainage performance in the future. 

Before storing your portable air conditioner, empty the tank and clean it with a solution of mild bleach and water – this will destroy bacteria in the tank after only ten minutes, helping preserve the tank’s original condition. 

Mold can be detrimental to health so it's important to remove it as soon as possible.

How Often Should I Drain my Portable AC?

You should drain the condensate tank manually when the machine beeps to say it’s full. There’s no benefit to emptying it early because you must turn it off anyway. 

Using a drainage hose, you never have to drain your portable AC because water will flow out of the condensate tank automatically. 

Self-evaporative portable air conditioners need draining every few days on average, but in dry environments, this could be once per week. 

We recommend inspecting the condensate tank every few hours to ensure it’s draining and collecting water as usual. 

Why Is My Portable Air Conditioner Filling Up So Fast?

Several factors can make your portable air conditioner fill with water more quickly than usual.

  • High humidity – more moisture condensing on the coils.
  • It’s newly installed or being used for the first time this season – new portable air conditioners take several days to break in, and extended periods of downtime can trigger a fresh boot cycle. 
  • Faulty condensate pump – this will send water to the drainage tank.
  • Plugged drain holes or tubes – these force water into the drainage tank.
  • Broken blower fan – increases ice build-up on the coils, which melts and drips into the drainage pan when the portable AC is off.

High humidity is the leading cause of portable air conditioners producing more water than usual. Steam from kitchens and bathrooms wreaks havoc on indoor humidity, making your portable AC work doubly hard. 

Open windows and droughts can also increase humidity, making your portable air conditioner work harder. 

The best way to reduce water production is to get your space down to temperature and run your portable AC on cycles – this will balance energy consumption and cooling performance, keeping your space temperate without costing the earth. 

About the Author Paul Cathro

Paul is an ex-HVAC engineer with 5 years 'in the trade'.

He acquired in 2022 and aims to make it the internet's most comprehensive HVAC resource for small homes in the next few years.

You can learn more about Paul's story here.

Browse his published work on the website here.

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