Dehydration

Dehydration or Thirst, sometimes displayed as H2O, is a derived statistic in Fallout: New Vegas in hardcore mode.

Characteristics
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.

Different foods and beverages have different effects on hydration. 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. Maize, Nevada agave fruit and prickly pear fruit are some of the grown food that reduce dehydration, and Caravan lunch, desert salad and gecko kebabs are crafted recipes that reduce dehydration. Beer, Nuka-Cola, Sunset Sarsaparilla and Pork n' Beans are examples of food and beverages which negatively affect hydration.