Yes, you are absolutely allowed to bring your own tumbler or reusable water bottle into Disney theme parks, and it is highly encouraged as a way to stay hydrated and save money. The only major restriction is that the tumbler cannot be made of glass, as glass containers are strictly prohibited for safety reasons (with the exception of small baby food jars). You can bring metal (like Yeti or Hydro Flask) or plastic tumblers of any size. Disney provides numerous water bottle refill stations throughout the parks, often located near restrooms or in newer lands like Star Wars: Galaxy's Edge. Additionally, you can walk up to any "Quick Service" food location and ask for a cup of ice water for free, which you can then pour into your tumbler. A "pro-tip" for 2026: while you can bring your own cup, you cannot use it to get free refills at the "Resort Refillable Mug" stations found at Disney hotels; those stations use RFID technology that only works with the specific mugs purchased at the resort. Bringing a large, insulated tumbler is one of the best ways to keep your water ice-cold during the sweltering Florida or California afternoons.