I have also had this occur in the hydraulic oil of an agricultural tractor. We were a bit worried that the water would turn the paper oil filter to mush, which would contaminate the hydraulic system. So we changed all 10 gallons and put in a new filter, also unblocked and cleaned the suction filter.
I don't think any of our members just do ground runs, but I know the IMC lads spend about an hour in cloud ( 100% relative humidity.) When flying VMC, I have never had the T+Ps not in the green.
p.s. B2N2... Water in the oil turns it into something resembling pale chocolate milk-shake. This is not just the dark oil caused by the combustion process..