However, a Cast Member at the security checkpoint may ask to open your bottle to check its contents, since metal water bottles are opaque. Just keep in mind that alcoholic beverages and glass containers aren't allowed inside the Disneyland Resort, as stated in the Rules.

Yes, Disneyland security cast members do check water bottles as part of the standard bag search and screening process at the park entrances. Their primary concern is two-fold: ensuring the bottle is not made of glass (which is strictly prohibited for safety reasons) and verifying that the contents do not include alcohol. While you are explicitly allowed to bring outside non-alcoholic beverages into the park, any open or unsealed bottles may be subject to a "sniff test" or visual inspection. Refillable plastic or stainless steel bottles (like Hydro Flasks or Yetis) are highly encouraged and are a staple for regular park-goers. Security will also check to ensure that any ice inside the bottle is not loose if it's in a cooler, though in a standard water bottle, this is rarely an issue. As long as your bottle is made of a safe material and contains water, soda, or juice, you will have no problem bringing it through. This policy is a great way for families to save money, as a single bottle of water inside the park can cost upwards of $5.