What case to use with треба?

Question

I know потрібне takes a nominative case for the object: Мені потрібна машина, вода, etc. What case does треба take? (When the object is a noun rather than an infinitive?) My intuitive answer would be genitive, Мені треба води, машини, but some people told me it's nominative, so I'm not really sure. Which is it, or are there multiple allowed options or does it depend on something more specific? Or is it just not correct to use it with nouns at all?

And more generally, how/where can I look this sort of thing up? Neither sum.in.ua nor slovnyk.ua seem to give this information (or even have examples that include it), unless they do and I just can't read in which case please point it out, it's entirely possible.

Answer 1

Your questions get more and more thoughtful and deep. This is great. On the other hand, for a language learner just memorizing the case is just fine; with practice, the correct case would come to you intuitively. Unless, of course, if you, indeed, are looking for an insightful and research-based answer.

Short answer: both are correct. It depends on where do you like to place the Subject at.

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So we are talking about Nominative vs. Genitive.

Observation 1: The Subject always goes in Nominative; the Nominative unequivocally points to the Subject.

Observation 2: There can be subjectless sentences; in this case, all nouns have case other than Nominative.

1. Мені(Dat) треба води(Gen) (roughly, "to me needed water") — here we have a subjectless sentence where none of я/мені or вода/води are Subjects.
   Somewhat similar to what you see in English sentences like "it is raining" where "it" acts as a dummy subject.
   • Confer: "я потребую води" (I need water) where all Subject-Verb-Object are clear.
   • Note: води Genitive comes from an ancient Partitive case.
2. Мені(Dat) потрібна вода(Nom) (roughly, "water is needed for me") — here вода is the Subject! Note that потрібна(Adjective) is agreed with вода(Feminine).
   • Confer: "мені потрібний дім", ("I need a house") the Adjective agrees with дім(Masculine).

Observation 3: Animate nouns (including those having facultative animacy) may shift your preference toward #2. For example, "мені потрібна машина" ("I need a car") subjectively sounds more natural to me (with вода both options sound equally correct).

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Summarizing all above,

• If you think that the main logical focus goes to мені (which, I believe, is the most common use), then use "мені треба води";
• If the main focus goes to вода (especially if you want to emphasize the contrast, e.g. when someone gives you beer instead of water ;-), you should use "мені потрібна вода".