Just to get it out of the way: Are you certain its not related to external factors? Heat, Caffeine, certain medications, salt, physical activities, some health conditions? If not, then hydrate throughout the day.
If its not helping, then take some time off, 3-7 days off. Then try again, see if the thirst is still there when you’re washing out.
Thirst and hunger is something common on subliminals, but an intense one is could be of a concern.
Edit: try reducing listening time, perhaps it will reduce the thirst.