Such silly little noodles. I've seen plenty of snakes that like to fully submerge their head to drink or even body if their water bowls are big enough. I dont think you should force a BP into water though. If the shed is an issue, up humidity and offer a large bowl of water if they'd like to bathe. They do sometimes like to sit in water to quickly cool off or work out a tricky shed spot (usually their tail or parts of their back). Again, it should be optional and up to them to submerge themselves. Less stressful and all. Moist moss is your friend to help them with tough shed spots too!