Learn Turkish: Ormanda susuzluk yaşarız diye çantaya üç şişe su koyarım. - I put three bottles of water in the bag just in case we experience thirst in the forest.

The word diye literally means "saying" and often translates to "because" or "so that". However, when you combine it with a verb in the aorist tense (like yaşarız), it creates a precautionary clause meaning "in case" or "lest". The speaker is taking an action to prepare for a possible future event.

Could I use the conditional and say yaşarsak diye here instead?

Yes, you can! Susuzluk yaşarsak diye (conditional) and susuzluk yaşarız diye (aorist) mean exactly the same thing in this context: "in case we experience thirst". Both structures are perfectly natural and interchangeable for expressing precautions.

Why use yaşamak (to live) rather than a verb for getting thirsty?

While you could use the verb susamak (to get thirsty) and say susarız diye, using the noun susuzluk (thirst) with yaşamak (to live/experience) is a very common Turkish collocation. Yaşamak is frequently paired with abstract nouns to mean "to experience" (for example, problem yaşamak means to experience a problem).

Why is it üç şişe su and not a noun compound like üç şişe suyu?