I've been doing this for years.

(It might have even been my post you read about this

)I first found out about it almost 30 yrs. ago when a friend of mine worked at DL during college. She told me that all the food venues would give you either a cup of ice, or a cup of ice water. Now that the parks sell soda in cans and/or bottles, it's even easier to just get ice. In the past,sometimes, you'd have to get the cup with water too, and then if you just wanted the ice, you either dumped out, or drank the water.
We went to DLR a few days ago and brought along our own cans of soda. Yes-it did make our bags a little heavy at the beginning of our day, but I got the free stroller, thanks to Disney Visa

(sorry only available at DLR

) and our whole family used it to carry our bags. The only sodas we bought that day were at lunch and we got those in to-go cups, as well.
There was a difference, however, at least at DCA as to what size cups you got. My DSis grabbed a few cups at Pizza Ooh Mow Mow, and they were small cups, no lids. However, when we got some ice cream at Burrbank, we got full sized cups, with lids.
Even with
DDP, I can't stand to use SC for bottled water

especially when cups of water/ice are free! And yes, many times when I've asked for my cups of ice/water, I've seen looks, and gotten comments from other guests. I've also told guests, while in line, that water is free at Disney!
Keep hydrated everyone!
