It's a shame to kill spiders.
Remember, given a choice, they will avoid you - so any notion that a spider is waiting to fall on you is just that - a notion. Spiders are far too clever to 'fall' anywhere. they travel sround doing what they do, and will always move in the opposite direction from any human activity.
The only place you will find them regularly is in the bath or basin - they walk around, slide in, and can't get out - they do NOT come up the plug-hole. Apart from the fact that there is an 'S' bend full of water that they couldn't get past, spiders are far too clean to go anywhere near a smelly wet dark drain pipe.
If you don't want to kill a spider trapped here, drape a towel over with the edge on the floor of the bath or basin, and the other end hanging down - it will climb out and go on its merry way.