A lot of people don't like the taste of tap water in Orlando so regular refillable bottles might not work for you.
An eco-friendly way to have nice tasting water at WDW is a portable filter bottle, the Brita http://www.brita.com/products/filtering-bottle/brita-bottle/ or Rubbermaid
http://www.amazon.com/Rubbermaid-20-Ounce-Filtration-Personal-Bottle/dp/B004RLNE5Q
The Brita worked well for us, lighter to carry than bottled water and you can ask for ice water at any WDW counter service and put it in the bottle.
An eco-friendly way to have nice tasting water at WDW is a portable filter bottle, the Brita http://www.brita.com/products/filtering-bottle/brita-bottle/ or Rubbermaid
http://www.amazon.com/Rubbermaid-20-Ounce-Filtration-Personal-Bottle/dp/B004RLNE5Q
The Brita worked well for us, lighter to carry than bottled water and you can ask for ice water at any WDW counter service and put it in the bottle.