Aqua pura corpori salubris est.

• aqua = water; nominative singular, feminine
• pura = pure; nominative singular, feminine, agreeing with aqua
• corpori = for the body / to the body; dative singular of corpus, corporis
• salubris = healthful, beneficial, wholesome; nominative singular here, describing aqua
• est = is

So grammatically, aqua pura is the subject, salubris is the predicate adjective, and corpori tells you for whom or for what the water is beneficial.

Because Latin often uses the dative with adjectives like salubris to show the person or thing affected.

So corpori salubris est means literally something like:

• is healthful for the body
• is beneficial to the body

This is sometimes called the dative of reference or dative with adjectives.

A native English speaker may expect a preposition like for or to, but Latin can express that idea just by using the dative ending.

Because salubris describes aqua, not corpori.

In this sentence:

• aqua pura = the thing being talked about
• salubris = what is being said about it

So salubris is a predicate adjective, and predicate adjectives agree with the subject, not with the dative noun.

That is why salubris matches aqua in case and number:

• subject: aqua = nominative singular
• predicate adjective: salubris = nominative singular

Meanwhile, corpori is separate and means for the body.

Because aqua is feminine singular, and salubris is the masculine/feminine nominative singular form.

The adjective salubris, salubre is a 3rd-declension adjective with:

• salubris for masculine/feminine nominative singular
• salubre for neuter nominative singular

Since aqua is feminine, Latin uses salubris, not salubre.

Because pura agrees with aqua in:

• gender: feminine
• number: singular
• case: nominative

Latin adjectives normally agree with the nouns they modify in gender, number, and case.

So:

• aqua pura = pure water

This is an attributive adjective: it directly describes the noun.

Because of est.

When an adjective appears with a form of esse (to be), it is often a predicate adjective:

• aqua pura ... salubris est = pure water is healthful

So the structure is:

• aqua pura = subject
• salubris = predicate adjective
• est = linking verb

Without est, the phrase could more easily be read as a noun with adjectives attached, but with est, Latin is clearly making a statement about the subject.

Latin word order is much freer than English word order because the endings show how the words function.

Putting est at the end is very common in Latin. In fact, many Latin sentences place the verb last.

So this order is natural:

• Aqua pura corpori salubris est.

But Latin could rearrange the words and still keep the same basic meaning, as long as the forms remain clear.

Yes. Latin allows several possibilities, for example:

• Corpori aqua pura salubris est.
• Salubris corpori aqua pura est.

These all mean essentially the same thing.

However, the original order is neat and natural:

• subject first: aqua pura
• then the dative: corpori
• then the predicate adjective and verb: salubris est

Different word orders can change emphasis, even when the core meaning stays the same.

Because Classical Latin has no articles.

So aqua can mean:

• water
• the water
• a water

The context tells you which English wording is best.

In a general statement like this one, English usually translates it without an article or with a general sense:

• Pure water is beneficial for the body
• Pure water is healthful for the body

Usually healthful or beneficial to health is better here.

In careful English:

• healthy usually describes something that has health
• healthful describes something that promotes health

So aqua pura corpori salubris est is more precisely:

• Pure water is healthful for the body
• Pure water is beneficial to the body

That said, many translations use healthy more loosely in everyday English.

Here they are:

• aqua, aquae = water
• purus, pura, purum = pure
• corpus, corporis = body
• salubris, salubre = healthful, wholesome
• sum, esse = to be

A learner should get used to recognizing that the word in the sentence may not look exactly like the dictionary headword. For example:

• corpori comes from corpus
• est comes from sum

The pattern is:

subject + predicate adjective + dative + verb

More exactly:

• aqua pura = subject
• corpori = dative of reference
• salubris = predicate adjective
• est = linking verb

You can think of it as:

Pure water is healthful to the body.

That is a very common Latin type of sentence: a subject linked by est to an adjective, with a dative added to show to whom or for what the statement applies.