I never had a problem in any of the 4 Disney parks last year. There were 8 of us and sometimes we would all get a free ice water at the same time. We asked for it with our CS meals as well, as drinks don't come with the combos(except for kids meals) I didn't even ask for "free ice water", I just said "May I please have cup of ice water?" If you say "I'd like water", they may assume you mean a bottled water.
I went to Disney 4 times before I read about the free ice water here. I just think of all the money I could have saved! I also hated drinking all that soda or sugary lemonade. I just bring the sugar free flavor sticks and save my money for other things.
Marsha