Yes, you can absolutely take a metal water bottle into Disneyland, and it is actually one of the best "pro-traveler" moves you can make. Disney allows guests to bring their own reusable bottles—whether they are plastic, glass, or stainless steel (like Hydro Flask or Yeti)—to stay hydrated throughout the day. The only restriction is that the bottle must not contain any alcohol and should not be used to smuggle prohibited items. Metal bottles are particularly popular because they keep water cold for hours in the California heat. Disneyland has installed numerous high-speed water refill stations throughout the parks (look for them near the restrooms in Tomorrowland, Galaxy's Edge, and near the entrance to Frontierland). Taking your own bottle saves you the roughly $5 to $6 cost of a single-use plastic water bottle inside the park. Just be aware that when you go through security, you may be asked to open the bottle for inspection, or it might trigger the metal detector, so having it out and ready to show the security cast member will speed up your entry process. Note that while the bottle itself can be metal, "loose ice" is not allowed in coolers, though ice inside your personal water bottle is perfectly fine.