Thirst is a derived statistic in Fallout 4.
Thirst is tracked on Survival difficulty like in New Vegas. However, the hydration value is tied to the caps value of the items, with the max amount of hydration one can provide being 167. Diseases do not affect the effectiveness of hydration. Drinking from a water source reduces thirst by 1 point per tick.
The character's thirst increases by 4 points every in-game hour and applies ever more severe penalties, up to and including death. Sleeping reduces thirst accumulation (1 point per hour instead of 4), while entering combat will cause the next check to happen faster, by 15 in-game minutes each time. Once thirst effects start applying, the player receives a malus according to the table below. Bonus effects from drinks will not apply if the player character is hungry (i.e. Parched or above).
Certain items can increase thirst. In this case, they decrease the food pool by 50% of their caps value. All cola-type items have reduced effectiveness when it comes to sating thirst, sating only huger by 40% of their caps value.
|10||Intelligence -2, Perception -1|
|18||Intelligence -4, Perception -3, Luck -1|
|24||Intelligence -8, Perception -5, Luck -2|
|30||Intelligence -10, Charisma -5, Luck -3, periodic damage|