Why Is There No Water
       In My Compressor 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
Image: Amazon.com


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.

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.

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