Step 1: The intended meaning is that water is the one thing Ravesh drinks, nothing else.
Step 2: The limiting word only should sit right next to the word it restricts, which here is water, not drinks.
Step 3: Only drinks water shifts the focus to the act of drinking rather than to water, and Drinks alone water is not correct English since alone cannot be used this way before a noun. Drinks only water places only directly before water, giving the correct restrictive meaning. The answer is Drinks only water.