Ours has a no nuts policy, and in Tom's room they have asked for us to consider not putting in strawberries as a girl in there has an allergy, but this isn't mandatory. It isn't a water only policy but I wouldn't mind if it was - I only send water and milk anyway (I assume a milk for lunch is ok?). In fact my boys only drink water and milk.

I suspect the idea of the water only policy would be in part education for the parents. Nearly every parent I know gives their toddler juice believing it to be healthy. If I didn't know some dieticians I'd probably do the same thing. I would love it if more parents had access to better information about what is and what isn't good for their child (diet wise).