How do I know if there is water in my fork I have a SunTour XCR fork. Not wanting to ruin it I am worried that a significant amount of water has penetrated beyond the seals. I have recently ridden the bike in rain, snow, and washed it in a bathroom with a showerhead.

The symptom that I am observing is the following. I just cleaned the stanchions, oiled them, compressed them rapidly to get oil beyond the seals, then wiped off excess oil and dirt, from the seals.

But unlike usually, when compressing the fork, there was a "whum" sound of air leaving the fork boots and passing throught some liquid at the seals.

On one hand, I had just put oil just there. On the other hand, I have never heared this sound (with a brand-new fork), when applying this procedure.

Should the fork be disassebled and dried? What other tell-tales are there that there is water in the a (spring-operated) suspension form?
The XCRs are very simple forks and unless specified don't have an oil or air damper so very user friendly. 

It is possible that water has got below the dust wipers but this is generally unlikely. 

The mechanism for a XCR is a sealed lock out unit and a coil. You should simply be able to drop the lowers off the fork without disrupting anything else to check them out for water and to ensure there's plenty of grease to protect the spring and other internals.

The 'whum' could be the stanchions being a bit sticky moving through the wipers but not much else I can think off.