After completely draining the tank, how to I evacuate the fuel system along with the injection?

If I found myself in this predicament after draining the tank, might blow through the fuel rail with compressed air then put enough fresh fuel in the tank to determine if the engine would start up and clean the rail and injectors using detergents already in the gasoline, or disconnect the fuel rail with the injectors attached, disconnect the injectors from the rail then clean the rail and send the injectors out for reconditioning.

I'd have needed to convince myself that significant water infiltration was occurring before doing any of this though. How did you do that?

Run some ethanol fuel through gets rid of water in no time flat. Then run a couple of tanks of regular fuel to get rid of the ethanol.

+1