In UK English at least, the word order feels very odd. "When he is thirsty, he even drinks water" would be better.
Good news... "When he is thirsty, he even drinks water" is among the accepted translations!
The audio for this one, even at slow speed is slightly distorted - "pije i vodu" sounds very much like "pije TY vodu." Granted, "ty" wouldn't make sense, but it would be better if the word sounded like what it is. I have reported it.
There is some strange echo there but I can't hear any "t".
What is the difference in usage of "kdy" and "když" if the translation is "when"?
Generally speaking, 'kdy' is interrogative and 'když' makes it conditional.
"Kdy má žízeň?" - When is he thirsty?
"Nevím, kdy má žízeň." - I don't know when he is thirsty.
"Když má žízeň, pije." - When he is thirsty, he drinks. (=if)