last year they let us bring water in. they have to let you bring in something anyway. people(like me) can become hypoglycemic at times(happens a lot with diabetes too) and need sugar/candy really quickly. really not the time or place to stand in line when you feel like that.
We have always brought bottled water and juice boxes for the kids with some small snacks. We have never had a problem. In fact my husband is always amazed that they don't care.
We always bring in water, snacks and a PB&J for my DD (dear daughter). She's a vegetarian and sometimes it's hard to find a meal on the kids counter service menus that she will eat.