Compressed Air Dewatering

Compressed air dewatering
(Last Updated On: September 18, 2020)

Compressors generate water every time they run. The hotter and more humid the air is that is flowing into the compressor intake, the more water will be driven down into the compressor tank. There are some steps that can be taken to help prevent a lot of this water from getting into the air line, hence this page about compressed air de-watering tips.

Drain the tank!

Every time the compressor runs water forms in the tank. Over time, that water level will increase to the point that the incoming air will pick up the free water and drive it out of the tank into the air lines. This is easily preventable. Drain the tank!

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If, at the end of a shift or workshop session the tank drain is opened and all moisture allowed to blow out, there’s none left to migrate into the air the next time the air is used in the air tools and this means less water to deal with at the air tool end of the air line.

Air Hose Storage

A typical air hose will have a checked coupling on one end, and an air connector on the other. If these terms confuse you a bit, please visit their pages on

If you are using high demand air tools and have plumbed them with an air hose or air hoses, after you have done your work, water vapor in the compressed air in those lines could condense out. The next time you connect that air line to an air tool, along with the first burst of compressed air, could come a slug of water. Not good for the air tool if it gets to it, for sure.

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The air hose provides mini-air storage and as the air cools, water condenses.

In one of their compressor manuals, Campbell Hausfeld suggests, and I thank them for the suggestion, that when the work is done for the day, if you can hang the air hose connector down (the connector is open all the time) if there is any water in the air line, it will drain out while hanging.

Not a crisis if you do not do this, but certainly a potential plus if you do.

Where is the filter?

The compressed air filter, or water trap, is often located at the exit from the compressor tank.

This provides immediate free-water removal as the air exits the tank, but then the compressed air enters the piping or the air hose.

Get more information on this Cambell Hausfield filter for air compressors by clicking here

Depending on how long the air pipes or air hose is, substantial cooling of the compressed air will occur as the air travels along. As noted compressed air is typically very high in moisture vapor. What happens to that vapor as it travels? It condenses out, is what.

Compressed Air Dewatering how to

Even though there is no free water entering the air main or air hose from the tank due to the filter being placed at the tank, water will still condense out as it travels to the air tool, and depending on how much vapor there was in the air to start with, that can mean a lot of free water still appearing at the air tool end of the line.

If possible, plum the air pipe or air hose to a wall location, add another water filter / water trap there, and that will remove the free water that has condensed in the air lines before it gets to the air tool.

Other suggestions about de-watering tips?

Any other ideas about how to easily and preferably cheaply de-water compressed air before that water gets to the equipment? Please add them here.

And check out this filter;

Hello, I am Bill, the Compressed-Air-Man. I have years of experience in industrial and residential compressed air applications, air compressors and general pneumatics. I created this site to help professionals, students, and DIYers understand and properly implement and maintain compress3ed air systems.


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