Hello there, Xinrui! Welcome to planDisney. We are so thrilled you are heading to Disneyland Resort soon!
You've brought us a great question! As someone who always has a water bottle or glass with me at all times to stay hydrated, it's one thing I worry about on trips and at the parks. Hydration is important to me, and it sounds like it is for you too. I took a look at the
Property Rules, and you can bring in a suitcase, cooler, or bag, as long as it is not larger than 24" long x 15" wide x 18" high (61 cm x 38 cm x 46 cm). Dry or loose is not permitted. So while it may be permitted, I am not sure I would recommend it as it seems like it would be a lot to deal with on a long park day.
My recommendation would be to bring in reusable water bottles in a backpack or something easier to carry around all day. There are
water bottle refilling stations located throughout the parks. You can also always ask for a cup of water from any quick service location as well. If you are set on bringing a suitcase of water, there are
locker rentals both inside and outside of the parks that could be helpful.
Xinrui, thanks so much for stopping by! You know where to find us if you have any other planning questions!
Carrie