This is a thoughtful question that shows reflection on the historical account.
Insofar as there is no answer mentioned in history books, it is not possible to give an answer.
If I were to guess, perhaps it would have aroused too much suspicion to bring water, or perhaps it was an emotional and sudden moment and he was not thinking about things, or perhaps some other reason.
Ayatollah Motahhari was of the view that it is not correct that they were without water for 3 days and nights. See https://www.al-islam.org/al-tawhid/vol13-no3/ashura-misrepresentations-d...
I don't think there is historical evidence that they were without food, however, the lack of water is much more dire.
God knows best!