Cur tantum aquae bibis?

Cur means why. It is a question word, and Latin very often puts question words near the beginning of the sentence, just as English usually does.

So:

• Cur = why
• Cur tantum aquae bibis? = Why do you drink so much water?

Latin word order is more flexible than English, but cur at the front is very natural.

Bibis means you drink.

It comes from the verb bibere, meaning to drink.

Here is the breakdown:

• bib- = the verb stem
• -is = you (singular)

So bibis is:

• 2nd person singular
• present tense
• active
• indicative

In simple terms, it means you drink or, depending on context, sometimes you are drinking.

Latin usually does not need a separate subject pronoun, because the verb ending already tells you who the subject is.

In bibis, the ending -is already means you singular.

So Latin can simply say:

• bibis = you drink

If Latin included tu, it would usually add emphasis:

• Cur tantum aquae tu bibis? = Why do you drink so much water?

But in a normal sentence, tu is not necessary.

This is one of the most important questions in the sentence.

Aquae is genitive singular, not accusative. It depends on tantum.

Here tantum means so much, and Latin often uses a partitive genitive after words of quantity. So the idea is literally something like:

• tantum aquae = so much of water

In this construction:

• tantum is the main quantity word
• aquae tells you of what

So the direct object of bibis is really tantum, while aquae depends on it.

This is similar to other Latin expressions such as:

• multum aquae = much water
• plus vini = more wine
• nihil temporis = no time

Here tantum is the neuter singular accusative form of tantus, tanta, tantum, but it is being used substantively—that is, as a word meaning so much by itself.

So in this sentence:

• tantum = so much
• aquae = of water

Together:

• tantum aquae = so much water

This is not the adverb tantum meaning only.

That is a very common source of confusion, because tantum can also mean only in other sentences. But here, because it is followed by aquae in the genitive, it means so much.

Yes, tantum can mean only as an adverb.

For example:

• Aquam tantum bibo = I drink only water

But in Cur tantum aquae bibis?, the structure is different. Here tantum is followed by aquae, which shows a quantity expression:

• tantum aquae = so much water

So in this sentence, tantum does not mean only. It means so much.

The grammar tells you which meaning is intended.

Yes. Cur tantam aquam bibis? is also good Latin and may feel more straightforward to a learner, because tantam agrees directly with aquam:

• tantam aquam = so much water

In that version:

• tantam = feminine accusative singular
• aquam = feminine accusative singular

So both patterns are possible:

• tantum aquae
• tantam aquam

The first uses a quantity word + partitive genitive. The second uses an adjective + direct object.

Both can mean so much water.

No. Latin word order is much freer than English word order.

Cur tantum aquae bibis? is a natural way to say it, but Latin could rearrange the words for different emphasis.

Still, some tendencies are worth noticing:

• cur often comes first
• tantum aquae works as a unit
• the verb bibis often comes near the end

So this sentence has a very normal and readable order, even though Latin does not rely on word order as much as English does.

It can potentially cover both ideas, depending on context.

Latin present tense often corresponds to English:

• you drink
• you are drinking

So Cur tantum aquae bibis? could mean either:

• Why do you drink so much water?
• Why are you drinking so much water?

Usually the context tells you which is more natural.

Tantum is accusative singular neuter.

That matters because it shows that tantum is functioning as the object of bibis:

• bibis tantum = you drink so much

Then aquae is added in the genitive to say so much of water.

So the grammatical structure is:

• Cur = why
• tantum = so much (accusative object)
• aquae = of water (genitive dependent on tantum)
• bibis = you drink

It is singular.

The form aquae can be several different cases in Latin, but here it is genitive singular.

Why singular? Because water is being treated as a mass noun, not as separate countable items. Latin commonly uses the singular for substances like this.

So:

• aquae here = of water, not of waters