Can you bring bottled water?

They will give you water at the park for free if you ask.

I went recently and left my water bottle in the car thinking they were prohibited. At the gate, people were bringing tons of stuff in... water bottles, canteens, etc.

Yes, and you can get water for free at any of their refreshment stations and restaurants. Just ask for a water cup.

Water is free

Yes

My wife walked in with a diet Coke.

Yes you can