Well you don't want it wet, you want humidity. Use a moisture holding substrate like Eco Earth, Cypress mulch, ReptiChips or something like that. And I've seen my boas drink for like 2-3 mins but never keep their head in the water for an hour. I would check for mites personally. Catching them sooner than later will help with getting rid of them plus I would definitely wipe down the outsides of your other snake cages as preventative and hopefully you have the snake QT in another room.
My dumerils somehow got mites and she was in the same room as my other snakes. But I wipe down all my cage stacks outside and bases with PAM once a month or so as preventative. Luckily no one else got mites(knock on wood). I think the dumerils got them from a hitchhiker I brought home as I forgot to retreat her glass tank as I was waiting for her AP cage. I moved her out of the room and have been treating her for about 1.5 months now and so far looking good.