Serpentine belts FTL

i own a 97 pontiac grand prix gt 3.8 ( not super charged) i have recently replaced the water pump , the alternator , and the belt tensioner pully 3 times and everytime the blet gets wet or i go thru a puddle of water depper than maybe 2 inches it makes the belt jump right off!!! if there where a nascar position for a serpintine belt mech i would get it i have mastered the art of putting mine back on in like 30 secs because it has happened so many times…

i have also noticed the actual pulley or knob that the belt is on is about 1-2 lines off center whenever the belt is on and tension has been applied this cant be good or helping with this issue im no mechanic but it just doesnt seem right and when i asked the mechanic he replied this is correctly installed … im at my whots end please someone help enlighten me b4 i lose my mind with this vehicle >>> is it a common occcurence with my vehicle

Are you sure the alignment of the pulleys is correct? It sounds like maybe the idler pulley may be worn out, causing it to “wobble”.

Try staring the car and pouring a SMALL amount of water onto the belt (stand back so you dobn’t get injured) and try to see exactly where the belt jumps off at. more than likely, the pulley just before that point is the one that isn’t aligned correctly