I also only fill the bowl maybe 3/4 full at most. This also helps prevent the snake from 'splashing' any out.

When changing water, it's usually down low so there's no spilling as I take them out. I dump and rinse in hot water (they get totally cleaned twice a month), then wipe the dish and put it back in the enclosure. I fill them IN the cage with a water bottle.

Best dishes to use are wide, heavy, and low, so you don't have to fill it really full.