I thought waterpark/hopper added one extra day to ticket but it looks like 1 day ticket does not do that.
1-Day Tickets with Park Hopper Plus Option
Your tickets are valid for admission to multiple theme parks on any one day from May 19, 2024 through May 19, 2024. Your ticket also provides one visit to a water park or other Walt Disney World fun during the same date range. Tickets are nonrefundable. After expiration date, the price paid for a wholly unused ticket can be applied to the purchase of a new ticket with an equal or higher price.
I guess it’s only the 2 day tickets or higher that add an extra day with waterpark/hopper.
Here’s the 2 day ticket giving 4 days to use:
Valid Ticket Dates
Your tickets are valid for admission to multiple theme parks on any 2 days from May 19, 2024 through May 22, 2024. Your ticket also provides 2 visits to a water park or other Walt Disney World fun during the same date range. Tickets do not have to be used on consecutive dates. Tickets are nonrefundable. After expiration date, the price paid for a wholly unused ticket can be applied to the purchase of a new ticket with an equal or higher price.