Hi Lynne! Welcome back to the Disney Parks Moms Panel! Your vacation is right around the corner, I hope that you are getting excited!
If I am remembering correctly some of the choices of cold beverages at the refillable mug station include soda, Hi-c (often fruit punch), POWERADE, Minute Maid (may be lemonade), and tea (sweetened, unsweetened, and possibly even a flavored tea.) They also have an area to dispense water from the soda machine; however I am not sure if it is purified. Please note, your resort hotel may not offer all of the drinks that I have listed, and drink choices may change at any time. Please be aware that this list is some of the offerings that I have experienced while vacationing at the Walt Disney World Resort.
I see that your children do not drink tap water. I do have a couple of suggestions for you. If you are on any of the
Disney Dining plans, you will receive a drink with your meal. You may be able to choose a bottle of water as your drink credit when you order your meal. Another option is to use a grocery delivery service such as Garden Grocer. Here you can order a case or two of bottled water to be delivered to your resort hotel. This may lessen the cost of buying individual bottles of water while you are in the park.
I hope that I have helped to answer your question! Have a magical vacation!
~Heather~