Learn Turkish: Sağlık için bol su içmek lazım. - For health, it is necessary to drink plenty of water.

Because this sentence expresses a general necessity, not something specific to one person. When you pair a plain infinitive (like içmek, meaning 'to drink') with lazım, it translates to the general statement 'it is necessary to drink'.

Could I use gerek instead of lazım in this sentence?

Yes, absolutely. In this structure, lazım and gerek are completely interchangeable. You could say bol su içmek gerek and it would still mean 'it is necessary to drink plenty of water'.

Why does the word for 'for' (için) come after the word for 'health' (sağlık)?

Because English uses prepositions (words that go before a noun, like 'for health'), but Turkish uses postpositions (words that go after). So, 'for health' translates literally as 'health for' (sağlık için).

I usually use çok to mean 'a lot'. Why does this sentence use bol?

While çok just means 'a lot' or 'very', bol means 'plenty', 'abundant', or 'generous'. In Turkish, bol is the most natural word to use when talking about consuming healthy, abundant amounts of things like water or fresh air.