Excess moisture in your air compressor system can cause some serious problems within the system itself and the tools you’re using at the end of the line. It’s important to remove this moisture so that you can extend the life of your air compressor system and tools.

This article will provide you with all the relevant information on why and how to get rid of this moisture in the air compressor system.

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Why is There Condensation & Moisture in my Air System?

Moisture is an inevitable byproduct from compressing air as all air contains a certain amount of water vapor – the volume of water in the air varies with the temperature and pressure, the higher the temperature the more water air is able to hold.

Air compressors work by forcing air into smaller volumes under very high pressures. As the air becomes pressurized, it is no longer able to hold as much water, so the water vapor begins to condense back into liquid form. This water in the air has to go somewhere, so it starts to form as condensate inside the air compressor system.

It forms not only in the air compressor receiver tank, but also in the lines and other components within the system. If water is allowed to accumulate, moisture will then find its way back into the air stream and potentially cause damage to the system and it’s end of line applications.

Therefore, it is essential to remove the excess moisture from your air compressor.

How to Remove Water From Compressed Air

While it’s impossible to stop moisture from entering your air compressor, you are able to get rid of a lot of it. This can be done in stages using different components that I will now present to you!

Draining the Air Receiver Tank

“Why is there no water in my compressor tank”, a visitor wrote in a recently. It seems that their compressor tank had been drained regularly and frequently had water in it but all of a sudden when trying to drain the tank of the compressor no water was coming out.

Nowadays when draining the tank, all that came out was a few drops of water. Yet water was travelling down the air hose and spraying out the nozzle of the blow gun, and sometimes out of other apertures on the compressor.

I suspect that the compressor was generating as much water as it always had, but that the problem was being experienced was that the tank drain had plugged up.

If you experience this problem the first thing that should be done is to check the tank drain.

Why Is There No Water In My Compressor Tank Tank Drain
Why Is There No Water In My Compressor Tank Tank Drain

To do that, and depending on the type of drain it is, with pressure in the tank open the tank drain fully. Shut the compressor off so that you can hear as water and air exits the tank drain. For more information on this visit our How To Drain Water From Any Air Compressor Tank guide!

If all you are hearing is a slight hissing and only a few drops of water exit and there is sufficient pressure in the tank, I suggest around 20 psi or more, it may be necessary to probe the drain opening with a wooden probe to try to dislodge any debris that may have blocked the drain.

Small bits of airborne debris will always migrate through the air filter and enter the compressor tank as air is being compressed. This minute-sized debris accumulates in the tank along with any free water to form a sludge.

If the compressor hasn’t been run for some time, this sludge dries out and hardens and can provide an effective block for the tank drain.

If the tank drain configuration on a specific compressor tank does not lend itself to probing with a wooden probe to clear the drain, it may be necessary to use a large wrench to remove the drain entirely and clean it or replace it.

If it becomes necessary to remove the tank drain ensure that you drain all the air from the tank before undertaking that procedure.

It is possible I suppose that the air exiting the compressor tank contains an exceeding amount of water vapor which condenses in the airline and has not condensed inside of a hot compressor tank, but I believe it’s more likely that the tank drain has become clogged over time.

Water Separator Filter

Mechanical separation is another great addition to a compressed air system to help remove moisture. Water separator filters remove large amounts of moisture from the air supply by utilising centrifugal force. They can typically remove between 40-60% of the water from the air, depending on your application, this may or may not be enough!

Air Dryers

We have 3 types of air dryers that could be used to remove the moisture from the air stream and these are:

  • refrigerated air dryers
  • desiccant air dryers
  • deliquescent air dryers

Refrigerated Air Dryers

Refrigerated air dryers work by chilling the air like a conditioning system as colder air holds less moisture than warmer air. As the air is cooled, excess water vapor condenses back into liquid, and then collects in a water trap and is removed through an automatic drain valve.

Desiccant Air Dryers

Desiccant air dryers are used for applications that require very dry compressed air. They work by removing water from the air through a chemical process. A desiccant is a solid that reacts chemically with water to form a bond.

Most desiccant air dryers use a tower containing either activated alumina or molecular sieve desiccants where the air is passed through using a blower. Some desiccant air dryers may also use heat.

This process is necessary and very effective for ultra-dry air but they tend to use more energy than other drying systems and can also consume 5-18% if the compressed air supply.

Deliquescent Air Dryers

Deliquescent Air Dryers are a little less common than the other two. They consist of one tank with desiccant beads that create a liquid effluent that extracts the moisture from air. This is then drained from the system. They offer a low dew point and are therefore not typically used in factories.

What Problems Can Moisture Cause in Compressed Air Systems?

Excess moisture will cause numerous problems in your air compressor and its components, with corrosion being the most serious. Corrosion is a chemical reaction between metal, oxygen and water, which is why metal rusts when in contact with water.

Keeping the air compressor system clean and dry is essential for longevity. Water moisture can result in:

  • damaged equipment and piping
  • blocked control lines
  • formed ice in cold temperatures that will clog or block components
  • corrosion of air tools
  • improper lubrication of air tools
  • poor spray paint results

FAQs (Frequently Asked Questions)

Why is there water in my air compressor?

Moisture is a byproduct of compressed air. When the air is compressed, it is no longer able to hold as much water vapor, this water vapor then turns into liquid form and will collect in the compressed air system.

What happens when water enters compressor?

Water can damage the air compressor and its components with the possibility of contaminating your applications. Water will cause piping to rust and even mix with other particulates or lubricant and cause tool issues at the end of the line.

Should you drain air compressor?

Yes, you should drain your air compressor daily or after every use! This is to stop the possibility of corrosion occurring .

How do I get water out of my air compressor tank?

To get water out of your air compressor tank you must drain it after every use. Open the drain valve if it is manual, and allow the moisture to drain from the tank – tilt the tank to remove any remaining moisture. Once the tank is drained, you can close the valve and continue using your air compressor!


If you have any questions regarding water in compressed air lines then please leave a comment below with a photo if applicable so that someone can help you!