You would definitely see tiny black specks in the water if they have been soaking that long but it wouldn't hurt. I would treat all the new snakes not just the ones soaking. Make sure you follow the PAM instructions exactly! Take snake and any water bowls out and then spray and let the cage air out good, you will have to wait at least 15 minutes I usually give mine 30-45 minutes to be safe. The fumes can actually kill your snakes that's why you take out water source and snake.
Sent from my SAMSUNG-SM-G890A using Tapatalk