Dehydration or Thirst, sometimes displayed as H2O, is a derived statistic in the Hardcore mode of Fallout: New Vegas and Survival difficulty in Fallout 4.
Thirst increases over time, and can be affected by certain consumables. Much like radiation, it has increasing effects with each increment of 200. It primarily affects Endurance, though Perception, Intelligence, and Agility will also suffer with more severe thirst. A level of 1000 causes instant death. Without outside interference, it will take three days to reach fatal levels of thirst. It is the fastest-acting stat in Hardcore mode, accumulating twice as fast as food and about five times as fast as sleep. Any type of water will reduce dehydration. A drink from a water fountain, faucet, toilet or any body of water will confer a 200 point reduction per drink. While most food has no effect on thirst, farmed or wild fruits and vegetables and some crafted recipes will reduce dehydration too. Alcoholic beverages, soda and some food will increase dehydration.
The longer one goes without drinking, the more they suffer from thirst. In general, the more valuable a drink is, the more it will stave off thirst. It is also important to note that partaking in chems and alcoholic beverages will further dehydrate.
| Minor Dehydration
|| Endurance -1
| Advanced Dehydration
|| Perception -1, Endurance -2
| Critical Dehydration
|| Intelligence -1, Perception -2, Endurance -3
| Deadly Dehydration
|| Intelligence -1, Perception -2, Agility -2, Endurance -3
| Fatal Dehydration
|| Intelligence -1
|| Intelligence -2, Perception -1
| Mildly Dehydrated
|| Intelligence -4, Perception -3, Luck -1
|| Intelligence -8, Perception -5, Luck -2
| Severely Dehydrated
|| Intelligence -10, Charisma -5, Luck -3, periodic damage
- Carrying water—whether it be purified or not—is the easiest way to combat thirst.
- The Survival skill enhances the hydration/dehydration amounts of all consumables. A higher Survival skill will make it necessary to carry less water, but also will increase how much consumables such as beer and pork n' beans will add to your dehydration.
- Carrying the Vault 13 canteen is good way to stave off dehydration without having to carry bottles of purified or dirty water.
- Water sources, such as lakes and water fountains, will reduce your dehydration by 200 per drink (230 if you have Camel of the Mojave perk).
- Strange as it is the amount your dehydration reduces by using sources of water other than aid items (such as foods items, bottled waters, etc.) is not affected by your survival skill.