Learn Hardcore Russian: Я пью только воду.

In Russian, the direct object of a transitive verb like пить (“to drink”) takes the accusative case. The feminine noun вода (nominative) becomes воду in the accusative, marked by the ending –у.

What does только mean here, and which word does it modify?

только means “only” or “just.” In Я пью только воду, it modifies воду, indicating that water is the sole thing you drink (and nothing else).

Why is только placed before воду? Could I say Я пью воду только?

Adverbs like только usually appear directly before the element they modify. Placing только after воду (as in Я пью воду только) sounds unnatural and ambiguous. The standard word order is пью только воду to clearly mark воду as the restricted element.

Can I move только elsewhere for emphasis? For example, Только воду я пью?

Yes. Russian word order is flexible. Только воду я пью front-focuses “only water,” emphasizing contrast (“I drink only water, not tea or juice”). The neutral statement is Я пью только воду, with no special emphasis.