Unless the aircraft has been sitting motionless for several hours you will not get any water out even if it is in there. It takes several hours for the water to settle.

Pulling the aircraft out of the hangar, or letting it sit on the ramp with a breeze blowing will jostle the aircraft enough to redistribute the water into the tank and you will not be able to drain any water.

If you let the aircraft sit motionless overnight in the hangar, then you will be able to drain the tanks and get the water out. But don't open the door and go up the airstairs to get the drain tool. That will be enough movement to redistribute the water.

When you drain, be sure to start with the highest tank in the system and work your way down to the lowest tank drain.

Any way, for small amounts of water the engine will not notice. Ice is not really a problem either as the King Airs have an oil to fuel heat exchanger to raise the temperature of the fuel to about 70 to 90 degrees so it always has the same density and that will melt any ice.

For other contaminates be sure to drain the strainer at least before every flight.

That is what I have always been told, and I have told others over the years.

Bill