I have an outward opening door on my P shaped bath with shower. It has a draught excluder wossname on the bottom edge, which seems to do the job. The time it didn't do the job was when, in a fit of exuberance, I removed it to clean it and didn't put in back on properly. The water ran down the shower door, into the groove of the draught excluder, up over the outer edge and down onto the floor.
Might be worth checking this isn't what's happening with yours.