The situation with Avgas (100LL) is a little different than the ethanol/gas mixture. Avgas is dyed blue, so when you're checking for water in the fuel system, it is readily apparent. Most modern aircraft have test ports located at the lowest point in the fuel system. There are specific fuel sampler cups that make the process easy. Typically, in a regularly flown aircraft, you'll only have a few drops of water.
However, with the ethanol/gas mixture, there would be larger percentage of ethanol/water that would need to be drawn off. I understand the chemical process of adding water to the fuel, but it seems like a waste of time and effort. Up north, during the winter, the ethanol would have been referred to as "dry gas".