The power of magicians and magic, the Talmud speaks plenty about.
One such example is that of Ze'iri and the donkey, in Sanhedrin 67:
זעירי איקלע לאלכסנדריא של מצרים זבן חמרא כי מטא לאשקוייה מיא פשר וקם גמלא דוסקניתא אמרו ליה אי לאו זעירי את לא הוה מהדרינן לך מי איכא דזבין מידי הכא ולא בדיק ליה אמיא
Basically, Zi'iri goes to Alexandra, Egypt and he buys a donkey that when he goes to give it drink (water), it turns into a board. He goes to the person who sold him it and he says "if you weren't Zi'iri, I wouldn't give you your money back...is there someone who buys something where they don't hit/test it with water first?"
So contact with water will break magic. But if sorcerer (I mean a real sorcerer) comes into contact with water (let's say standing in the river, or on the beach, with feet touching the water, or they're swimming) can they perform kishuf or will the water prevent them? What about in rain if it touches them?
