How to serve water at a barn wedding?

Hi! Our venue is a barn with no access to running water and a question I keep coming back to is how we're going to provide water for our guests. We are planning on doing a buffet style dinner, most likely with BBQ. Since it's buffet, the place settings will be pretty paired down at the table - napkins and flatware on the table, dinner plates stacked at the buffet table. Not sure what to do about glasses/water. Ideally, there would be large glass bottles of chilled water available on every table for guests to fill/refill their own cups, but since we're not hiring any waitstaff, there is no one and no water hookup to refill the bottles once they're empty. I figure my only options are the large self-serve tabletop dispensers, or coolers/basins of water bottles in ice. I see downsides to both - so I'm wondering what other brides in this situation did/are doing. Thanks!