If a star has large gas giants in it, those may possibly have moons that have habitable conditions as well, as the gas giant may radiate enough heat to allow liquid water, which is the agreed substance that must be present for any life to form.
You are forgetting Star Trek Season 1 Episode 26 'The Devil in the Dark', where Captain Kirk and Spock encountered the Horta which was a silicon based lifeform.
Horta says, NO KILL I.
In Season 3, Episode 22 'The Savage Curtain', Kirk and Spock dealt with the Excalbians, which were molten lava based lifeforms.
Yarnek says, Which is stronger, Good or Evil?
Anyway, the bottom line is you obviously don't need water for every form of life, just most forms of life.