It said "da" was acceptable in place of "når", yet I got it wrong.
"Da" is not used for repeated actions.
Meaning to get thirsty is a repeated action?
No, but the sentence presents a repeated habit, which calls for "når."
So basically "da" is used mostly for past actions like "I bought this when I went to the store"?
Then it's når.
What about the present "when I see you"? or "I'll believe it when I see it"?
why no v2 rule in the second part?