"You drink water."
Translation:Ihr trinkt Wasser.
I think it should work for all three. Now that you've brought it up, maybe the other options will get added.
"Sie" can be made to work here ("Sie trinken Wasser."). In this case, "Sie" is the formal singular "you". But, as you noted, this could also be interpreted as "they". Because they both use the same form of the verb, it's not possible to disambiguate the two given the sentence by itself (but one would hope than in an article or a conversation, which was which would be clear).
"Ihr" (plural familiar form of "you") works as written.
"Du" can be made to work, but the form of the verb changes slightly to "trinkst", so "Du trinkst Wasser."
Someone Please help >.<
I remembered German word order can be very flexible. So I tried 'Wasser trinkt Ihr.' but duolingo said no.
Isn't it acceptable as long as the verb stays in the second place of a sentence?
I've been told so by not only one person and some websites, and Duolingo itself some while ago!
Is there anything I've missed?
No. Interchanging the order of the verb and the subject turns the statement into a question. In German statements, the verb is always the second idea in the sentence, except in a dependent clause, where it is at the end. See here for more details: http://www.dartmouth.edu/~german/Grammatik/WordOrder/WordOrder.html
Except for the imperative?
...or is that something different?
Yes, in the imperative the first position is essentially left empty (as with many questions). I suppose a command could be considered a "statement", although I hadn't been thinking of the word being used that way. So,
"Trinken Sie Wasser?" = "Do you drink water" or "Are you drinking water"
"Trinken Sie Wasser!" = "Drink water!"
"Trinken Sie Wasser." unless it is someone who doesn't really want you to drink that water glumly making the command anyway, makes little sense.
The simple "You drink water." should be "Sie trinken Wasser."
sie trinkst is always wrong.
sie trinkt: she drinks sie trinken: they drink Sie trinken: you (formal) drink
Other correct answers: du trinkst: you drink ihr trinkt: y'all drink
Other conjugations: ich trinke: I drink er trinkt: he drinks es trinkt: it drinks wir trinken: we drink
(of course sie gets capitalized at the start of a sentence too)
So remember there are 9 pronouns in German, but he/she/it have the same conjugation, and they/you(formal)/we* have the same conjugation. The only time you need to look at the conjugation is to differentiate between she and they/you(formal)
*not sure if the 1st person plural is ALWAYS the same as the 3rd person plural/2nd person formal