I Just purchased an 03 33 outlaw. Does anyone know where the fill for the fresh water tank is??

Hmmm, under the hatch beside the motor? Or beside the fuel fill on the side of the boat, but, I am just guessin'

Its under the steps that lead into the cabin.

What he said. You have to un-screw the top cap and take the tank out to fill it up. I put a tank under the rear bench seat with more capacity than the one under the step.

I plumbed in a line to fill mine. Hard to believe they set it up like that.