Mike- Maybe try leaving a water bowl out of an enclosure for a week or two? Place the water bowl in the enclosure once a week when you are cleaning or after feeding? Do this with 1-2 snakes and see how it works? Find out if they pound water when you only offer water like this? Might be something to experiement with as it seems no one who doesn't use bowls has responded.

Another thought- perhaps a shorter, longer water dish of some kind which would go along the length of the tub could work? We all use round, what about a rectangular or trianglular bowl for a corner or lengthwise in the tub. Someone did suggest those big triangle/corner bowls you can get at petsmart but I'm thinking more of a rectangular crock.

ex: say you have a 41qt tub, use a 3-6qt tub as a water dish going along the length(even the front width) of the tub.

I hope you get what I'm trying to explain here. Let me know if this sounds foggy to you.