I know that English sometimes uses "you" in a command for emphasis, but generally we don't. "Give me water" is the command. Duo does not use "you" in its English commands, so that's one way you can tell.
I think your "You give water to me" should be accepted. If it comes up again, use your answer and report it if it is counted wrong.
(You gave me water = Usted me dió agua/Tú me diste agua. past tense)