If you drop film in water before exposure it can damage it by leaving spots or sticking together. If it happens after exposure, the best route is to totally wet it, keep it wet and then process with a good prewet before the process starts.

If you drop your camera in water and know the guts got wet, place it in distilled water and soak well, then dry well. Check to see if it works. If so, you are clear. Remove the film beforehand and wash well then run the process cycle when the film is still wet.